LED professional Review (LpR) – Sept/Oct 2022 – LpR#93 by Luger Research e.U.

ReviewISSN 1993-890X The Global Information Hub for Lighting Technologies and Design Sept/Oct 2022 | Issue www.led-professional.com 93 p 20 p 36 p 52 Interview: Prof. Georges ZISSIS Toulouse 3 University Vertical BartenbachIllumination Retrofit Linear Tube Lamps Seaborough Research Commentary: Jan Denneman, Good Light Group Lighting Design: Tiffany House Technologies: HCL LEDs, VCSELs ManufacturingADBHeadlights:ofComplexShapesOpticalLSRPartsSeepages44-50 ⊡

YoursSincerely,

Research–Innovation–

Thecommentary,writtenbythechairmanoftheGoodLightGroup,Jan Denneman,discussesthereplacementoftwilightbygoodlight.

SiegfriedLuger LugerResearche.U.,Founder&CEO LEDprofessional,TrendsinLighting,LpSDigital&GlobalLightingDirectory InternationalSolid-StateLightingAlliance(ISA),MemberoftheBoardofAdvisors MemberoftheGoodLightGroupandtheEuropeanPhotonicsIndustryConsortium

WealsolookatvariouslightinginnovationsincludingHuman-Centric LightingLEDs,Adaptive-DrivingBeamHeadlights,promisingLinearTube LampsandVCSELs.

Inthedesignarea,wediscusshowVerticalIlluminationisunderstoodin lightingdesignandhowmoderndesigncanandshouldbeappliedin variousapplicationstoday.Thisissuealsoincludesapresentationofa designproject:TheTiffanyHouse.

Wearesureourreaderswillenjoythisissueandlookforwardtoreceiving yourfeedbackateditors@led-professional.com.Wearealwaysinterested ininnovationsandwouldbehappytovisityouatyourboothattheLight+ BuildinginFrankfurt.

ThisLpR#93issuespansawiderangeoftopics,fromlightingresearch, variouslightinginnovationsandontoapplicationandlightingdesign. Inhisinterview,ProfessorZissis,aleadingﬁgureinthelightingsector, givesusaninsightintothelatesttrendsandﬁeldsofresearch.

Design

CONTENT OVERVIEW 6 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design Issue93/Sept-Oct/2022 4 EDITORIAL COMMENTARY 8 ReplacingTwilightwithGoodLight byJanDENNEMAN,ChairmanoftheGoodLight Group NEWS 10 InternationalLightingNews LIGHTINGINTERVIEW 20 ProfessorGeorgesZISSIS,Toulouse3 University,France compiledbyEditors,LEDprofessional LPSDIGITAL 26 LpSDigital:LightingConference& Exhibition2022 LIGHTINGDESIGNPROJECT 28 TiffanyHouse byLichtvisionDesign LIGHTINGDESIGN 36 VerticalIllumination byWilfriedKURZ,Dipl.DesignerMLL, ApplicationDesigneratBartenbachR&D

Research MEASUREMENT 58 HowtoAssesstheEyeSafetyof VCSELs–Introduction byGüntherLESCHHORN,Dr.,TianyuanCAO, KarhikIYER,Dr.,InstrumentSystems 66 ABOUT|IMPRINT ADVERTISINGINDEX 1 Dow 2 OSRAM 3 Würth 5 Nichia 9 Röhm 11 WAGO 12 Lumileds 13 Dow 14 MOSO 15 EdisonOpto 16 Alanod 17 AcalBFi 18 InstrumentSystems 19 Lumitronix 51 Zhaga 56 LpSDigitalAwards 57 LpSDigitalConference 62 LEDprofessionalReview 63 GlobalLightingDirectory 64 GoodLightGroup 65 TrendsinLighting 67 LEDprofessionalReview 68 Lumileds

byMennoSCHAKEL,Nichia

AUTOMOTIVE 44 Adaptive-Driving-BeamHeadlights: ACollaborativeApproachtoEfﬁcient ManufacturingofComplexShapes OpticalLSRParts byMartijnBEUKEMA,FrançoisDEBUYL, HannesRIEGER,JakeSTEINBRECHER,Kevin VANTIGGELEN;DowandELMET LAMPTECHNOLOGIES 52 HiddenChallengeandItsSolutionfor RetroﬁtLinearTubeLamps

byDr.MikeKRAMES,PieterSIX,Seaborough

OVERVIEWCONTENT Issue93/Sept-Oct/2022 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design 7 HCLLED–ADVERTORIAL 42 ImproveAlertness,FocusandComfort withBiologicallyEffectiveLight

ReplacingTwilightwithGoodLight

■ J.D.

Thebestwaytostayinrhythmistobe outsidealoteveryday.Afewhoursof morninglightisespeciallygood.Daylight isalwaystherightlightforourbiological clock,andourbodyrespondspositively toit.Ifyoucan’tbeoutside,makesure youareinsideclosetoawindowduring theday,lessthanameterawayand facingthewindow.Otherwise,your bodywillstillonlyexperiencetwilight.

JANDENNEMAN,CHAIRMANOFTHEGOOD LIGHTGROUP

Humankind,ourspecies,Homo Sapiens,hasbeenaroundforabout thirtythousandyears.Formostofour relativelyshorthistory,wewere outdoorsduringtheday.Ashuntersand gatherers,welivedofftheediblefood wefoundoutdoors.Soweautomatically gotenoughdaylighteveryday.This ensuredthatourcircadianrhythmskept pacewiththetimeofday.Inrecent centuries,however,humanshave increasinglybeguntoliveindoors.Since theindustrialrevolution,thistransition hasbeenveryrapid.Wenowspend mostofourlivesindoors(90%).

Lifeonearthhasdevelopedover hundredsofmillionsofyearsunderthe inﬂuenceofthe24-hourrhythmofthe sun’senergy,lightanddarkness.In ordertocopewiththis,24-hourrhythms havealsodevelopedinallformsoflife: theso-calledcircadianprocesses. Theseprocessesaretheoldestand mostfundamentalprocessesthatmake lifepossible.Lifeusesthelightofday andthedarknessofnighttokeepin syncwiththerhythmoftheplanet.

AtLight&Building,wewillseemany innovationsintheﬁeldofenergyefﬁcient andsmartlighting.Itwillbeuptothe lightingmanufacturerstoactuallybring theseinnovationstomarketandprovide thebillionsofpeoplewhositinside,in thetwilight,everydaywithgoodlight.

Ifthisisnotpossible,makesureyou havegoodlightingthatmimicsdaylight ascloselyaspossible.Forthis,itmust havethesamerhythmasdaylight: dynamicinintensityandlightcolor. Duringthedayitmustbesufficiently strong,atleastfivetimesstrongerthan whatyouareusedto.Otherwiseyour biologicalclockwillnotreactproperly. Goodlight,i.e.therightlightattheright time,canchangeyourlife.Alotoflight duringthedayandcozy,dimmedlight atnight.Youwillnoticethatyouwake uprested,canhandlemoreduringthe dayandarelesslikelytofeeldepressed. Goodlightisjustasimportantforyour well-beingandhealthasgoodnutrition andsufficientexercise.

JanDENNEMAN

Hefoundedseveral internationalconsortia, suchastheGlobalLighting Association,Zhaga Alliance,theConnected LightingAllianceand LightingEurope.Janwas PresidentoftheGlobal LightingAssociationfrom 2007-2017andPresidentof LightingEurope from2013-2017.

JanDENNEMANisFounder andChairmanoftheBoard oftheGoodLightGroupas wellasHonorary AmbassadoroftheGlobal LightingAssociation. TheGoodLightGroupisa non-profitorganizationthat promotestheuseofGood Lightindoors.Goodlightis daylightorelectriclight withcomparablebeneficial effects.

Fewpeoplerealizethattheintensityof lightindoors,evenwithelectriclightson, iscomparabletoorlessthanthe intensityofdaylightoutsideatthetime ofsunriseandsunset.Soweareinside alldayinthetwilight!Duringthedaythe intensityismuchtoolowandatnight muchtoohighcomparedtothelight outside.Ourbodiescannotinterpretthe constantsignalsoftwilightproperlyand ourcircadianrhythmgetsoutofsync withrealtime.Everydaythatwedonot getenoughdaylight,ourpersonal circadianrhythmlagsbehindbyabout 15minutes.Afterjustafewdays,our personalclockcanbemorethanan hourbehind.Thishasconsequencesfor ourhealth.Whenyougotobed,youfall asleepbecauseyouaretired,butyour bodyisnotyetreadyforagooddeep sleep.Duetosuperficialsleep,your bodydoesnotrecoversufficientlyat nightandyoudonotwakeuprested. Duringthedayyouarelessfitthanyou wouldliketobeandyourmood becomesgloomy.

Ifyourecognizethesesymptoms,itmay indicateadisruptedrhythmduetoa lackofdaylightorlightatthewrong time.Manypeoplesufferfromthis.

“Goodlightisjustas importantforyourwell-being andhealthasgoodnutrition andsufﬁcientexercise.”

Janhasmorethan40years ofexperienceinexecutive rolesinsustainability, innovationandbusiness developmentandheld seniorinnovationand marketingrolesatPhilips Lighting(nowSignify) duringtheindustry’s transitiontoLEDand IntelligentLighting Systems.

Recruitingandholdingontoqualiﬁedstaff experiencedinsustainableproductdesign andmanufacturingwillalsobecome increasinglychallenging.TheEUregulatory driveonsustainabilityisdirectlyimpactingall sectors,fromtextiletoelectronicsorcement, andallthesecompaniesarequicklytryingto buildupcapacityinternallytostayaheadof theregulatorytrendsandthemarket.Sales maydecrease,notonlybecauseproductsare moredurablebutalsobecausetheircostis verylikelytoincrease.Customerswill ultimatelyhavetocoverthecostofthe additionalinvestmentneededtoredesign productsandprocesses,andregulators acknowledgethis.

least,weexpecttoseeDigitalProduct Passports(DPP)usedtoreportinformationfor eachsingleproduct–includingevery substancefoundinaproduct.Considering thatmanyelectronicproductscontainupto 4,000differentsubstances,DPPreporting requirementscouldendupbeingextremely cumbersome.

Ontopofthesenewinitiatives,theEuropean Commissionisalsoexpectedtoreviewand updatesuchregulationsastheWaste FrameworkDirective(WFD);WasteElectrical andElectronicEquipment(WEEE)Directive; RestrictionofHazardousSubstances(RoHS) Directive;andRegistration,Evaluation, AuthorizationandRestrictionofChemicals (REACH)Regulation.

LumiledsAnnounces AgreementwithRequisite LendersontheTermsofa ComprehensiveFinancial RestructuringtoAccelerate Long-TermGrowth

Theamountofinformationthatcompanieswill beobligedtocollectandmakeavailablewill increaseexponentially.LightingEurope expectsthattoday’sEnergyLabelwillevolve intoaSustainabilityLabelthatcouldalso includearepairabilityscoreandalifecycle assessment.Furthermore,aspreviously mentioned,companiesmustensurethatany andallsustainabilityclaimscanbefully substantiatedwithevidence.Lastbutnot

LightingEuropeisanestablishedcredible voiceintheEUsustainabilitydebate,regularly talkingwithregulators,NGOsandothertrade associationstoexplainthespeciﬁcitiesof lightingandvoiceourmembers’ recommendations.LightingEuropemembers receiveregularupdatesonregulatorytrends andlatestdevelopments,givingthemthe informationtheyneedtobeproactive–not reactive–andtotranslatesustainability requirementsintobusinessopportunities.To learnmoreaboutLightingEurope’swork, pleasevisithttps://www.lightingeurope.org. ■

establishesharmonizedruleson sustainabilityforconstructionproducts.

Ifyouthinkthelightingindustryissubjecttoa lotofregulationnow,toparaphraseaclassic rocksong,‘youain’tseennothingyet’.In Marchofthisyear,theEuropeanCommission adoptedaproposalforacomprehensivenew legislativepackagecalledtheSustainable ProductsInitiative(SPI).Partofthe Commission’sﬂagshipGreenDeal,theSPI essentiallyaimstoensurethatonlythemost sustainableproductsaresoldinEurope.

• ConstructionProductsRegulation:

• EUGreenPublicProcurement(GPP): introducesgreenrequirementsinpublic tenders.

Todothis,theproposalsincludedintheSPI looktoempowerconsumerstosaveenergy, repairproducts,andmakesmart environmentalchoiceswhenshoppingfor newproducts.Ofparticularinteresttothe lightingindustryistheSPI’sproposalforan EcodesignforSustainableProducts Regulation(ESPR).Thiswouldrepealand replacethecurrentEcodesignDirectivethat ourindustryisbynowverymuchfamiliarwith. LiketheEcodesignDirective,detailsasto whatisandisnotsustainablewillbedecided attheproductlevel.

ButtheESPRisjustthetipoftheiceberg. There’sawholeslewofsustainabilityinitiatives onthehorizon,eachofwhichwillhavea directimpactonthelightingindustry.Take,for example,theinitiativesdesignedtoempower consumersbypreventingso-called ‘greenwashing’.Undertheseproposals, companieswillnotonlyberequiredto substantiateanyclaimsrelatingtoaproduct’s sustainability,they’llhavetodosousingthe methodssetoutintheSubstantiatingGreen Claimsinitiative.Anyclaimthatdoesnot followsuchmethodswillbedeemed misleadingandbesubjecttosanctions.

• RighttoRepair:aseriesofmeasuresthat aimtofosteracirculareconomyby ensuringthatproductscanberepairedand notsimplyreplaced.

ACrowdedLandscape:

HowtheEU’sMany SustainabilityInitiativesWill ImpacttheLightingIndustry

LightingEuropeCanHelp: Notonlyistheregulatorylandscapeextremely complex,itisalsomovingfast.Whilethe reviewofecodesignrulesforlightsourcesis settobeginin2025,thetaxonomyreporting obligationshavealreadystartedthisyear. Moreso,alltheobligationswe’vementioned areexpectedtoapplyby2026and2027–lessthanfour–ﬁveyearsfromtoday.

Otherkeyinitiativesinclude:

LumiledsHoldingB.V.(“Lumileds”orthe “Company”),agloballeaderininnovative lightingsolutions,announcedthatithas enteredintoarestructuringsupport agreement(the“RSA”orthe“Agreement”) withitslendersholdingasignificantmajorityof theloansoutstandingunderitsprepetitionfirst liendebtfacilityonthetermsofa comprehensivefinancialrestructuringthat wouldsignificantlyde-leverageandstrengthen itsbalancesheetbyover$1.3billion, accelerateLumileds’growth,andenable furtherinvestmentininnovationtopursue additionalstrategicopportunitiesthroughthe injectionofupto$275millionofliquidity.

• EUGreenTaxonomy:providecompanies, investors,andpolicymakerswithdeﬁnitions forwhicheconomicactivitiescanbe consideredenvironmentallysustainableand shouldbeprioritizedforﬁnancialinvestment andpubliccontracts.

TheESPRwill,withoutadoubt,requireeven morefromthelightingindustry.Inadditionto theenergyefficiencyrequirementsofthe currentregulation,theESPRwillinclude specificrequirementsrelatingtolifecycle, durability,useofrecycledcontent,repairability, andrawmaterialusage.Allthesenew sustainabilityrequirementswillbeevaluated andintroducedinproductspecificrules,also forlighting.Thankstoourindustry’swealthof experiencewiththeEcodesignDirective,and LightingEurope’sleadershiponthefile,weare well-positionedtoshapethenextgeneration oflightingrequirements.

• CorporateGovernanceSustainability Reporting:establishesrequirementsfor howcompaniesreportontheir Environmental–Social–Governance(ESG) performance.

WhattheLightingIndustryCanExpect: Whatdoesallthismeanforthelighting industry?Tostart,companieswillneedto rethinkhowtheydesigntheirproducts.In additiontobeingenergyefﬁcientand complyingwiththerecentlyintroducedquality parametersandlabellingrequirements, productswillalsoneedtobedesignedsothat theyarerepairableandofferincreased durability–bothofwhichwillrequirethat necessarysparepartsareavailableforseveral years.Whilethelattercouldopennew revenuestreamsforOEMs,theymustalsobe preparedtocompeteagainstothercompanies producingandsellingthesespareparts.

Toefficientlyimplementthede-leveraging,a narrowlyfocusedprepackagedChapter11 plan(the“Plan”)involvingonlyLumileds’U.S. andDutchentitieshascommencedinthe U.S.BankruptcyCourtfortheSouthern DistrictofNewYork(the“Court”).Lumileds’ European,Asian,andotherforeign subsidiariesandaffiliatesarenotincludedin thefilingandareunaffectedbytheChapter11 process.TheCompanyhasobtainedthe

necessarysupportfromitslenderstoconﬁrm thePlanpriortocommencingitsproceedings andexpectstomeettherequirementsto conﬁrmthePlanandemergefromChapter11 withinapproximatelysixtydays.

todriveinnovationinLEDtechnologyandoffer newproductsandsolutionstoourcustomers. Iwouldliketothankallofourvalued employees,customers,vendors,suppliers, andsponsorsfortheirongoingsupport.”

Showvisitorsinterestedinsolutionsforstreet lighting,aswellasareaandlandscape lighting,willﬁndaproductofgreatinterestin

Elsewhereonthebooth,willbeNichia’sH6 LEDSeries,whichheraldsaneweraofLED adoptionbydeliveringtheindustry’shighest joint-boostincolorqualityandefficacy.By combiningthecompany’saccumulated phosphortechnologywithKSFnarrow-band redphosphorandTriGain®technology,Nichia hasoptimizedthelightspectrumand overcomethetrade-offbetweenefficacyand CRI.Theportfolioextendsfrommid-powerto chip-on-board(COB)products,presenting idealsolutionsforapplicationsthatinclude retail,hospitality,andoffices.

TERMSOFTHERESTRUCTURING SUPPORTAGREEMENT

“Ournumberonepriorityistodelivernever beforepossiblesolutionsforlighting,safety, andwell-being,”addedMr.Roney.“This comprehensiveliquidityandde-leveraging solutionwillenableustobeanevenmore attractiveandstrongerpartneraswecontinue

TakingcenterstagewillbeDynasolis™,anew LEDtuningsolutionthatregulatescircadian rhythmsbysimultaneouslyadjusting melanopicilluminanceandcolortemperature whilemaintaininghighCRIandhighefﬁcacy. Thebuildingindustryisincreasingly encouragingdesignsthatbringmorenatural lightindoors,withhumancentriclighting (HCL)andcircadianlightinggainingattention. MostexistingHCLsystemsworkbychanging CCT(correlatedcolortemperature),thevisual element.However,Nichiaalsofocusesonthe non-visualelementthattrulyaddresses humancircadianrhythms,fromwakingupto goingtosleep.Dynasolis™achievesthis effectbyofferingbothcolorandspectrum tuning,rangingfromenergizingazuretoa peaceful,calmingwarm-whitehue.By combiningtwoseparateLEDspectra,building marketssuchashealthcare,educationand ofﬁceatlasthaveasolutionthatprovides independentcontrolofthiscriticalfunctionality, allowingbiologicallyeffectivelighttoenhance moodandwellbeingonasustainablelevel.

“Overthepastfewyears,wehavebeenhard atworktransformingourcoststructureand innovationpipeline,whichhasallowedusto capitalizemoreeffectivelyonfuturemarket trendsasaleaderinthelightingindustry,”said MattRoney,CEOofLumileds.

BUSINESSASUSUAL

TheRSAalsocontemplatesacommitment fromcertainofitslendersofupto$275million indebtor-in-possession(“DIP”)financing, availableaspartoftheChapter11process. SubjecttotheCourt’sapproval,theDIP financing,togetherwiththeCompany’s availablecashreservesandcashprovidedby operations,isexpectedtoprovidesufficient liquidityforLumiledstocontinuemeetingits ongoingobligations,includingallobligations tocustomers,vendors,andsuppliers,aswell asemployeewages,salaries,andbenefits programs.

NoneoftheCompany’sbusinessoperations outsideoftheUnitedStatesandthe NetherlandsarepartoftheChapter11 proceeding.TheCompanyhasﬁled”ﬁrstday” motionstoobtaintherequisitecourtauthority fortheCompanytocontinueoperatingits businessesandfacilitiesintheordinarycourse withoutdisruptiontoitscustomers,vendors, suppliers,oremployees.

Aspartoftheseﬁrstdaymotions,the Companyhassoughtcourtapprovalto continuetopayallvalidamountsowedto vendorsandsuppliersastheycomedue.In addition,theCompanyexpectsthat employeeswillcontinuetoreceivetheirusual wagesandbeneﬁtswithoutinterruption.

LEDTechnologyInnovations fromNichia

Evercoreisactingasinvestmentbankerfor theCompany;Paul,Weiss,Rifkind,Wharton& Garrison,LLP,andLatham&WatkinsLLPare actingascorporateandrestructuringcounsel toLumileds,andAlixPartners,LLP,asﬁnancial advisor.PJTPartnersisactingasﬁnancial advisorforanadhocgroupofLumileds’ lenders,andGibson,Dunn&CrutcherLLPis actingasthegroup’slegalcounsel. ■

“Wehaveproactivelytakenstepsto de-leverageourbalancesheetgiventhe ongoingchallengespresentedbyglobal supplyconstraints,COVID-relatedissues,and thecrisisinUkraine.Thisrecapitalizationwill enableustofurtheraccelerateoureffortsasa market-leadinginnovatorwithinthespecialty lightingindustry.Webelievethatthemost effectiveandefﬁcientwaytoaccomplishthis isthroughaprepackagedChapter11process thatwillbeaccompaniedbyasigniﬁcant increaseinourliquidityposition.We appreciatethesupportofourlenders,who recognizethelong-termvalueandenhanced potentialLumiledswillcreatewitha strengthenedbalancesheet.”

MoreinformationaboutLumileds’ restructuring,includingaccesstoCourt documents,willbeavailableat https://dm.epiq11.com/Lumileds orby contactingEpiqCorporateRestructuring, LLC,theCompany’snoticingandclaims agentat+1800-497-9116(fortoll-free domesticcalls)and+1503-520-4495(for tolledinternationalcalls)oremailing Lumiledsinfo@epiqglobal.com.

AtLight+Building2022inFrankfurt,Nichia, theworld’slargestLEDmanufacturerand inventorofthehigh-brightnessblueandwhite LEDswillshinethespotlightonanumberof ground-breakingLEDtechnologiesthatare settingthepaceinthegloballightingindustry. AsNichiacontinuesdevelopingforabrighter world,visitorstotheexhibitionwillseethe latestfruitsofitscutting-edgeR&D.

UnderthetermsoftheRSA,theexisting securedlendersareexpectedtocommitto support,andvoteinfavorof,atransaction that,whenexecuted,willreducethe Company’sfundeddebtbyapproximately $1.3billion,fromapproximately$1.7billionto $400millioncomprisedoftakebackdebtand post-petitionloans,whichwillbecombined intoa5-yearexitfacility.

Optisolisdeliversanaturalcolorrendering performancethroughtheexceptionalCRI valueofover98andanR9ofover94.

NichiawillexhibitatLight+Building2022in Hall8,BoothD60. ■

“Whetherit’sbringingvitalityandwellbeingto healthcare,work,andleisurespaces,or ensuringvaluableobjectsareappreciatedand preserved,theofferfromNichiaempowers fixturemanufacturerstoenhancetheworld with“LightsoGood”,lightingsolutions focusedonthequalityoflight,”saysDrUlf Meiners,ManagingDirectoratNichia Germany.“Whateveryourprojector application,wehaveasolutionthatwillbring notablebenefits,includinglowerpower consumption,widercolorgamut,higher resolution,andeventheabilitytoencourage comfortandregenerationinhealthcare settings.Welookforwardtodiscussingyour specificrequirementsattheshow.”

Vitasolis™emitsanaturalwhitecolorwitha highcontentofblue-greenenergyprovento stimulateawakeningandsupportsavibrant life.Thisproductcanbeusedinofﬁces, schools,hospitals,andmanyothersforthe

NEWS INTERNATIONALLIGHTING

theformofNichia’sHPScolorLEDseries. Thisproductfaithfullyreproducestheemission colorofahigh-pressuresodiumlamp(HPS), whichfindscommonuseinroadandoutdoor lighting.Unlikeexistingmarketsolutions,the keyfeatureofNichia’sHPScolorLEDisthatit maintainsthenostalgicatmosphereofthe landscapewiththesameemissioncoloras HPSwhileimprovingcolorvisibilitythroughits higherCRI(Ra≥70).Lightingfixturesequipped withthisLEDnotonlyofferalifespan2.5 timeslongerthanthatofHPS,butalso providehigherluminousefficiency,lower energyconsumption,andlessimpactonthe ecosystem.

purposeofimprovingproductivityand learning.

Optisolis™notonlyshowsobjectsinamore vividway,italsopreservesthemattheirbest, helpingpreventthedegradationofartworks, printedmaterials,andtextiles,while simultaneouslydeliveringsigniﬁcantenergy savings.

6GLiFiTechnology

Light-basedtechnology,formaking telecommunicationsmoreaccessiblein remoteandruralareas,istobedevelopedina collaborationbetweentheUniversityof StrathclydeandFriedrich-AlexanderUniversitätErlangen-Nürnberg(FAU)in Germany.

ProfessorHaraldHaas,Directorof Strathclyde’sLiFiResearchandDevelopment Centre,hasreceivedaHumboldtResearch Awardforhisresearchachievementstodate. Thisawardenableshimtocollaborateona topicofchoicewithProfessorRobertSchober atFAU.Thecollaborationwillinvestigatethe useofpoint-to-pointfreespaceoptical(FSO) communicationstoprovideaneffective solutiontothe‘digitaldivide’through6G communications.Theprojectwillalsoexplore THz(terahertz)communications,on frequenciesbetween300GHz(gigahertz)and 10THz,aswellasopticalwireless communications,between10THzand1PHz (petahertz).

Nichiawillalsoshowcaseits2-in-1tunable white,singlelight-emittingsurface(LES), mid-power3030LED.Thisinnovativeproduct allowsforhighercolorqualityofuptoRa≥90. Itdeliverselegantcolortuningandmixing withinasingleLEStoprovideeasier integrationintoedge-litwaveguides.Italso enablescreativedesignpotentialsuchas thinner,sleekeropticalluminairedesigns, eliminatingtheneedforbulkycolormixing chambers.

Inaddition,theresearchwillexaminetheuse ofreconﬁgurableintelligentsurfaces(RIS)for allpotential6Gfrequencybands.RISare electromagneticdeviceswithelectronically controllablecharacteristics,whichcan manipulatetheimpactofanincomingsignal.

FurtherNichiainnovationsatLight+Building 2022willincludeOptisolis™LEDsandCOB solutionsthataccuratelymimicnaturallight withoutproducinganyharmfulUVlight.

“Ourgoalistohaveaffordablefree-space opticalcommunicationsfor6G,ina frameworkwhichenablesmeshandmultihop networkingtogetaroundhillsandobstacles. Oursystemisdesignedtobeself-powered becauseweusesolarpanelssimultaneously forpoweranddataharvestingsothatitcould beinstalledanywhere,evenontreesorany othermastwherethereisnoaccesstothe powergrid.Theoperationalcarbonfootprint ofthesecommunicationsystemsis,therefore, zero.Wearealsoaimingtoredirectsignals whensomething,anobjectoranindividual,is inthewayandblockingthesignal.Wewillbe advancingopticalRIS,whichissomethinglike asmartbillboardorwallpaperthatreﬂectsand concentrateslighttowardsaLiFireceiver.I havechosentoworkwithFAUbecause,like Strathclyde,ithasanationalandinternational reputationasaresearch-intensiveandleading university.”

ProfessorHaasisanAlexandervonHumboldt Professorandarecognizedpioneerintheﬁeld ofLiFi,orlight-basedcommunications technology.Ina2015TEDTalk,hepublicly demonstrated,fortheﬁrsttime,new technologyforreceivingdatawithordinary solarcells.Hisresearchoffersameansof overcomingproblemsofaccessto technology,particularlyinremote,ruralor desertregions.AccordingtotheInternational TelecommunicationUnion,2.9billionpeople–morethanathirdoftheworld’spopulation–haveneverusedtheinternet.

“Peopleindata-deprivedareascanreallyfall behindinthemodernworldandwhatisreally transformationalaboutthisisthemoveaway fromradiospectrumtoopticalspectrum.We areaimingtousetheopticalcommunications spectrumintheinfraredregiontobeam wirelessdatasignalsoverhundredsofmeters totensofkilometers,usingsolarpanelsas bothdatareceiversandenergyharvesters. WehavebeenrunningatrialinOrkneyin whichordinarysolarcellsandlaser transmittershavebeenusedtoquadruplethe dataratesofresidentsonGraemsay.”

“Itisanabsoluteprivilegetocollaboratewith ProfessorSchober,whoisamongthetop researchersinwirelesscommunicationsinthe world,”saidProfessorHaas.Humboldt researchawardsarepresentedbythe AlexandervonHumboldtFoundationtosenior researcherswhohavepredominantlylivedand workedoutsideGermanyforatleastfive years;arerecognizedinternationallyas outstandingresearchersintheirfield;have hadasignificantimpactontheirown disciplineandbeyond,andareexpectedto continueproducingcutting-edgeresearch. ■

ProfessorHaassaid:“Itisgenerallyaccepted that,toachievestep-changeimprovementsin net-zero,datarates,latency,userexperience andcoverage,radicallynewsolutionsare requiredfor6Gandovercomingthedigital divideisparticularlyimportant post-COVID-19.”

NewCIEReporton Spectroradiometry

TechnicalReportCIE250:2022canbe purchasedintheCIEonlineshop: www.techstreet.com/cie.

DOEReportsExaminethe StateofCurrentCommercial UVLEDs

However,light-emittingdiode(LED)GUV sourcesandfixturesavailabletodayhavelow efficienciesrelativetovisibleLEDsorotherUV sources(suchasmercurylamps).Drivenby demandforpandemicpreparedness measuresinbuildingsandgoodindoorair quality,manyemergingGUVR&Dactivities targetapplicationeffectivenessthrough increasedsourceefficiency,improvedfixture design,andenhancedreliability.

TheU.S.DepartmentofEnergyhasreleased tworeportsaimedatunderstandingthe currentstateandviabilityofcommercial ultraviolet(UV)LEDproducts.RTIInternational conductedthesestudiesthroughacontract withKeyLogicSystems,workingwiththeLED SystemsReliabilityConsortium(LSRC).

AtLight+BuildinginFrankfurtfrom2–6 October2022,visitorstotheInstrument Systemsboothwilllearnmoreabout high-precisionandtraceablycalibratedlight measurementsystems(Hall8.0H38).

Thedocument,publishedasCIE250:2022, supersedesthealmost40-year-oldreportCIE 063-1984.Practicallyoriented,itexplainsthe basicmeasurementprinciplesandprovides practicalinstructionsforthemeasurementof irradiance,radiationdensity,radiationintensity andradiantﬂux,includinginstrument calibration.Inaddition,thereportdescribesin detailthephysicaleffectsrelevantto spectroradiometricmeasurements,andin particulartheestimationofmeasurement uncertainties.Themeasurementuncertainties occurringineverymeasurementquantitatively determinetheaccuracyofthecalibration chainfortraceablemeasuredvalues.

InstrumentSystemsisinvolvedinnumerous professionalassociationsandorganizations, thatensureinternationallyuniform implementationofmetrologicaltraceabilityto theSIunitsystemandcreateapractically usablerealization.

TheseincludetheInternationalLighting Commission(CIE),towhosetechnicalworking groupsInstrumentSystemshasbeen committedformanyyears.Forexample,as earlyas2007InstrumentSystemswas instrumentalincreatingtheCIE127 documentthatdeﬁnesrecommendationsfor themeasurementofLEDs.Instrument Systemsmaintainsclosecontactwiththe world’sleadingnationallaboratoriessuchas PTB(Germany),NIST(USA),KRISS(Korea), ITRI(Taiwan)andNIM(China). ■

UnderthescientiﬁcdirectionofInstrument Systems,theTechnicalCommitteeTC2-80of theCIEhaspreparedanewtechnicalreport onthespectroradiometricmeasurementof opticalradiationsources.

purchasedintheCIEonlineshop: www.techstreet.com/cie.

• InitialBenchmarksofUVLEDsand ComparisonswithWhiteLEDsfocuseson theconstructionandinitialperformanceof commerciallyavailableUVLED componentsinradiometricand current-voltagetests.Atestmatrix containing13differentUVLEDswas createdinassociationwiththeLSRC. Testinginvolvedatleast22samplesof eachcommerciallyavailableproduct(asof June2021).Inaddition,twocommon, commercialwhiteLEDsweretestedto provideabenchmarkagainstblue-pumped whiteLEDs.Readthereport.

• OperatingLifetimeStudyofUVLED Productsfocusesonthelong-term performanceandreliabilityofthesameset ofcommerciallyavailableUVLEDs. Understandingthefailuremodesandfailure ratesofUVLEDsisimportantin understandingGUVproducteffectiveness overtimeandimprovingUVproduct reliabilityattheLED,lamp,andluminaire level.Thisinformationiscriticalto

TheCOVID-19pandemichasputaspotlight ongermicidalultraviolet(GUV)radiationforair andsurfacedisinfection.Thistechnologyarea representsagrowingopportunitytoimprove indoorairqualitywhilesavingenergyover high-ventilationapproaches.

ThenewtechnicalCIEReport250:2022 containsbasicmeasurementprinciplesand practicalinstructionsforthespectroradiometry ofopticalradiationsourcesinthewavelength range200–2500nm.Itisprimarilyconcerned withthemeasurandsirradiance,radiation density,radiationintensityandradiantﬂux, togetherwiththequantitiesderivedtherefrom. Inaddition,itprovidesadetailedoverviewof thephysicaleffectsrelevanttotheestimation ofmeasurementuncertainties.

Thereport,preparedundertheaegisofDr. TobiasSchneider,ChiefScientistatInstrument Systems,offersacomprehensiveinsightinto therelevantterminologyandthefundamentals ofcalibrationofspectroradiometricmeasuring instruments.Itisapracticalguidetothe identiﬁcation,understandingand quantiﬁcationoftherelevantcomponentsof measurementuncertaintyandcanbe

Asaleadingmanufactureroflight measurementtechnology,Instrument Systemshasalwaysattachedparticular importancetothemetrologicaltraceabilityof measurementresults,andofferscalibrated instrumentswithhighabsolutemeasurement accuracy.Traceablemeasurementresultsare usuallystatedinSIunits.TheSIunitsare disseminatedbycalibrationofthemeasuring instrumentsbasedonachainof measurements.Ifthismeasurementchaincan beunequivocallytracedtoaprimary representationofSIunits,thisisreferredtoas themetrologicaltraceabilityofa measurement.Itconstitutesaquantitative descriptionoftheaccuracyofthecalibration chainandmetrologicaltraceability.

Atraceablevalueisthusreferencedtoa recognizedstandardthroughanunbroken chainofcomparativemeasurementswith knownmeasurementuncertainty.Thatiswhy wealsospeakofNISTorPTBtraceability. InstrumentSystemswillbepresentingits high-precision,traceablycalibrated measurementsystemsatLight+Buildingin Frankfurtfrom2–6October2022.

”Thiscriticalworkmovesourindustry’s knowledgeforwardinanemergingarea,”said KevinBenner,LeadResearchEngineerfor Current,whowasnotinvolvedintheRTI studies.”Aswastrueintheearlydaysof white-lightLEDs,itisimportantforLED manufacturers,equipmentengineers,andend userstohaveaccesstothisinformationin orderforthemtoaidinproperdeploymentas thetechnologyevolves.”

thatmeettheeconomicandenergygoalsof ourcustomers,whilepositivelyinfluencingthe nightskyweallshare.Welookforwardto moreCreeLightingproductsachievingLUNA qualification.”SearchableontheSSL QualifiedProductsList(QPL),LUNA-qualified productsareeligibleforenergyefficiency rebatesandincentivesdesignedforSSLV5.1 products.LUNAsetsperformance requirementsforspecificcategoriesof outdoorLEDfixtures,sothatmunicipalities, energyefficiencyprogramsandotheroutdoor lightingdecision-makerscanbettersupport theirenergyreductiongoalsandabidebydark skypoliciesandordinances.LUNAalsohelps specifiersfulfillthelightpollutionandtrespass requirementsofLEEDandWELLbuilding programs,andhelpsprojectsfollow applicationguidanceinthejointInternational DarkSkyAssociation-IlluminatingEngineering SocietyModelLightingOrdinance.

DLC:FirstProductsQualified UnderNewLUNATechnical Requirements

TheDLCannouncedtheﬁrstproductsadded toitsLUNAQualiﬁedProductsList(QPL)after beingtestedanddeterminedtomeetthenew LUNAVersion1.0TechnicalRequirementsfor outdoorLEDluminaires.TheDLCreleased LUNAV1.0inDecemberandbeganaccepting applicationsfromsolid-statelighting(SSL) manufacturersinterestedinqualifyingtheir

“CreeLightinghasalwaysbeenaleaderin LEDlighting,deliveringindustryleadingenergy performance,whileprovidingsolutions designedtoreducethenegativeeffectsof lightpollution.TheadditionofDLC’sLUNA programallowsustodemonstratetoour customersandindustrystakeholdersthat energysavingsandreducinglightpollutionare notmutuallyexclusive,”JonathanVollers,Cree LightingDirectorofEngineeringServices,said. “WebelieveLUNAprovidestheindustrywitha complementarytool,alongwithgoodlighting design,tohelpachievetheIESandIDA’sFive PrinciplesforResponsibleOutdoorLighting. Weareproudtodoourpartwithsolutions

productsinApril.Eighteenspecific3000K modelsoftheXSPWVersionBWallMount Luminaire,manufacturedbyCreeLighting,are thefirstoutdoorLEDproductspublishedon theDLC’sLUNAQPLfollowingtestingof productperformanceandattributesbyan accreditedlabandrigorousreviewbyDLC staff.“TheDLCcongratulatesCreeLighting foritsleadershipandcommitmenttoquality outdoorlightingthatworksforpeopleandour naturalenvironment,”DLCExecutiveDirector andCEOChristinaHalfpennysaid,“Weare veryproudtohavetheLUNAprogramasa resourcefortheenergyefficiencyindustryand welookforwardtoworkingwiththelighting communitytopopulatetheLUNAQPLwith productsthatareenergyefficient,ensure appropriatenighttimevisibilityforpeople,and worktomitigatethegrowingproblems associatedwithlightpollution.”

InadditiontomeetingtheDLC’sSSLV5.1 efficacythresholds,LUNA-qualifiedproducts mustcomplywithadditionaldimming,control andshieldingrequirementstoensureefficient useoflightingenergy.TheLUNAprogram alsointroducesrequirementsforlight distribution,correlatedcolortemperatureand dimmingcontrolstoreducelighttrespassand skyglow,whilesupportinglightinstallations thatbothprovideappropriatevisibilityfor peopleandmeetrecommendedmethodsand voluntaryguidelinesfordark-skybest practices.TheDLCnotes,however,thatthe technicalrequirementsapplyonlyto

developingproductswithhigherefficiency, lowercarbonfootprint,andsignificantly reducedenvironmentalimpactthanthe lightingtechnologiestheyreplace.The studyemployedthreestressteststo examinethereliabilityofeachproduct. Resultsfromstresstesting,alongwithan extensiveliteraturereview,identifiedspecific failuremechanismsacrosstheseUVLEDs.

NewZhagaSpecifications

Tobuildtrustintheinteroperabilityof components,onlycertiﬁedNFCreadersand NFC-programmabledevicescancarrythe Zhaga-NFClogo.However,beyondbuilding trust,theuseofZhaga-certiﬁedproductsalso providesanarrayofbusinessadvantages, including:

crossvendorharmonizedmethodofNFC programmingforin-ﬁelduse.

andtosupportanumberofhomeautomation devices.

Buildingtrustthroughcertification

SolvetheSmartLuminaire DataManagementProblem

Ofcourse,reapingthesebenefitsdependsnot onlyonallsmartluminairesandrelevant componentsbeingNFCenabled,butthatthey becompatiblewithinteroperablemaintenance tools(i.e.,NFCreaders).ThisiswhereZhaga comesintoplay.“Anincreasingnumberof lightingapplicationsrequirereadingout parametersandchangingthesettingsofLED driversinthefield,”saysRupp.“Butbecause LEDluminairemanufacturerscurrentlyusea varietyofmethodsforconfiguringLEDdrivers andreadingparametersthroughoutthe productlifecycle,doingsocanbecomplex, cumbersome,andinefficient.”Forexample,in additiontoNFC,othercommonmethods usedbyLEDluminairemanufacturersinclude settingoutputcurrentwithplug-inresistors andprogrammingLEDdriversthroughthe DALIinterface.“Theresultisthatmaintenance staffmustmanageallthesedifferentmethods, eachofwhichrequirestheuseofdifferent tools,”addsRupp.Zhagasolvesthisproblem throughspecifications,whichitcallsBooks. “Luminairemanufacturers,installers,system integrators,andutilitycompaniesnowhave theoptiontoselectonlyoneprogramming toolthatwillworkwithallfield-maintenance applicationsfromallvendorsimplementing Book25andallNFC-programabledevices implementingBook24,”saysRupp.Whereas Book24isgearedtowardsluminaire manufactures,Book25definesaBluetooth LowEnergycommunicationprotocolforthe communicationbetweenthe field-maintenanceapplicationonasmart deviceandtheNFCreader.Indoingso,it enablesmaintenanceandreplaceabilitywitha

Ifyou’veeverpaidforsomethingbyhovering yourdebitcardorphoneaboveacardreader, thenyou’veusedNearFieldCommunication (NFC)technology.Whilemobilepayments maybethebest-knownuseofthis technology,itisbynomeanstheonly.Infact, thisextremelyshort-rangewireless communicationstandardcanbefoundin everythingfromtabletstospeakers, wearables,andgamingconsoles.NFCisalso regularlyusedforquicklypairingdevices, managingaccesstopublictransportation,

• CertiﬁedNFCreadersavailablefrom multiplesuppliers

white-lightLEDoutdoorproducts,whichdo notincludesometypesofoutdoorlighting. Forexample,non-white(amber)luminaires, whichmaybeappropriateforsettingssuchas environmentallysensitiveareas,areexcluded fromLUNA.Thisisbecauseofinconsistencies interminologyandperformanceduetothe lackofstandardizedmetrics,whicharestillin developmentfornon-whitelight.Formore informationonthis,pleaseseetheDLC’s recent“Non-whiteLightSourcesforNighttime Environments”whitepaper,andarelated FAQ. ■

• ConsistentNFCreadersupplyforluminaires withNFCprogrammablecomponents

• Easytoidentify(trademark)ifNFCreader workswithvendorsoftwarewrittenfor ZhagaNFCcapablecomponents

Onetoolforallfield-maintenance applications

“Together,thesetwospeciﬁcationssolvethe datamanagementproblemsofsmart luminairesbyenablinginteroperable maintenancetoolsthatensureconﬁgurable luminairesareeasytoserviceovertheirentire lifecycle,”concludesDeeDenteneer. ■

Specifically,Book25definesaBluetoothLow EnergyGATT-ServicethatNFCReader manufacturerscanimplementforthe communicationbetweenthe field-maintenanceapplicationonasmart device(cellphone,tablet,etc.)andtheNFC reader.Thisallowsthefield-maintenance applicationtoreadandwriteparameterson NFC-enabledLEDdriverswithouttheneedfor acable-basedconnection.Fieldmaintenance withBook25mayalsobeusedforother componentsthatrequireprogramming,such assensorsorconnectivitynodes.

ZhagahasalsodevelopedtheZhaga-NFC certificationprogramforBooks24and25, whichisavailableforRegularandAssociate ZhagamembersandisprovidedbyZhaga accreditedtestcenters.Recently,NFC readersproducedbyFEIGELECTRONICand TERTIUMTechnologybecamethefirstNFC readerstobeZhagacertified.“Tohavea devicefullycompliantwithZHAGABook25 certificationisaguaranteeofperfect integrationandfunctionalityofourreaders withourcustomerLEDDrivers.Furthermore, itqualifiesourreadersandourpresenceinthe LEDlightingmarket,”statesAxelPenzo, TERTIUMTechnology.“Thecertification processaccordingtoZHAGABook25, performedbyanindependenttesthouse, givesuserstheconfidenceofgettinga compatibleandprovenproduct.In complementtotheproven“QualifiedReader” accordingtoZHAGABook24,thetwonew mobilereadersaccordingtoBook25area furthersteptoacompleteproductfamilyfrom FEIGELECTRONICfortheLEDlighting market”,saysWolfgangMeißner,FEIG ELECTRONIC.

• CertiﬁedNFCprogrammablecomponents availablefrommultiplesuppliers

NFCcanalsoplayanimportantroleinmaking lightingmoresustainable.“NFCletsyou managedataovertheluminaire’sentire lifecycle,fromproductiontoinstallation, maintenance,replacementandrepair,”adds Rupp.“Havingsuchlifecycledatanotonly helpsincreaseefﬁciency,italsopromotes productsthatuseamodulardesignandthat canbeeasilyrepairedandupgraded–what Zhagacalls‘CircularityLighting’.”

• Certiﬁcationlogosprovideanestablished brandforproductmarketing

“Whilethelightingindustryhaslongleveraged thebenefitsofwirelessconnectivity,NFC couldfurtherreduceitsrelianceoncoded mainsandwiring,”saysDeeDenteneer, SecretaryGeneraloftheZhagaConsortium. Zhagaisthegloballighting-industry consortiumwiththemissionofstandardizing theinterfacesofcomponentsofLED luminaires.AsArnulfRupp,ChairofZhaga’s ModuleDriverInterfaceWorkingGroup explains,NFCallowsmanufacturersto configuresuchlightingcomponentsasLED driverstotheirspecificationsbothbeforeand afterinstallation.“Thisabilitytochange settingsin-the-fieldmeansyoucanconfigure fixturesfaster,reduceinventory,andperform on-the-spottroubleshooting,”hesays.

Asmissionsfordeepspaceexplorationand spacehabitatsareputontheagenda, astronautsneedtowithstandbeingtestedby multiplestressorsinconﬁnedandisolated conditionsduringsuchlongﬂights,especially becauseindeepspaceexploration,problems suchassignaldelaysmakeastronautsfeelthe anxietyofbeingfarawayfromEarthandthe psychologicalfearofdeepspace.

Theresultsofthecontrolgroupshowedthat theparticipants’negativeemotionsand anxietycontinuedtoincreaseovertime, whereasthegrouprandomlyexposedto multicolorlightingthatchangedeverythree hoursdidnotshowanysignificantincreasein negativeemotionsandanxiety.Themost significanteffectwasobservedonthefourth day,GLM-RManalysisindicatedthatthe anxietylevelonthefourthdaywassignificantly higherthanthatonthefirstdayinboth groups.

generalizedanxietydisorder(GAD).Asfor statisticalanalysis,achi-squaregenerallinear modelrepeatedmeasures(GLM-RM)was usedtomeasuretheeffectofisolationon emotion,anxiety,andself-ratedhealthscores.

Afterwards,theexperimentgotstarted. Twentyparticipantswererandomlydivided intotwogroups:onegroupthatwasexposed tomulticolorlightingandacontrolgroup, whichwasexposedtoastatic,monotonous whiteinterior.Inthemulticolorlightinggroup, from8a.m.to10p.m.everyday,thecolorof themulticolorlightwasrandomlychanged everythreehours.Eachparticipantentereda separateisolationroom.Duringtheisolation, theparticipantswerenotallowedtouseany carrierssuchasmobilephones,computers, TVs,oriPads.Buttheycouldreadpaper booksanddoyogaandotheractivities.The participants’psychologicalstatewas recordedontheﬁrstday,thefourthday,and theseventhday.At4:00-5:00p.m.onthe testday,theexperimentersaskedthe participantstostartﬁllingoutthepaper questionnaire.Afterthequestionnaireswere completed,semi-structuredinterviewswere conductedtorecordtheparticipants’ self-evaluationandsubjectivefeelings.Each interviewlastedabout5-10minutesandwas recordedforsubsequenttranscriptionand qualitativeanalysis.

Theauthorﬁrstpreparedthenecessary materialsandmethods.Twentyhealthy participants(10malesand10females,allof Chinesenationalityandmostly21to27years old)fromXiangtanUniversitywereselected. TwentyisolationwardsoftheXiangtanCentral Hospitalwereused,whichwereall3.5meters long,3meterswide,and2.2metershigh. Eachroomwasfurnishedwithachairanda table,abed,andabedsidetable.Thewalls andtheceilingwerepaintedwhiteandthe ﬂoordarkgreyThesewerethetwomain colors,apartfromthedoor,chair,table,and dresser,whichwerealightwoodcolor. Neutralcolorswereusedtoreduceanyeffects oftheroomonthecolorstobeusedinthe experiment.Moreover,PhilipsHueBluetooth wireless16millioncolordynamiclightbulbs werechosentoprojectthecoloredlightinthe multicolorlightingrooms.Themulticolorlamp wasplacedinthemiddleareabetweenthe deskandthebedintheisolatedroomto ensurethattheparticipantswereaffectedby themulticolorlightinginmostdailyactivities.

HowScientistsTestedthe EffectofMulticolorLighting onImprovingPeople’s PsychologicalState

Ontheseventhdayoftheexperiment,the anxietylevelwasalsosignificantlyhigherthan thatonthefirstday,buttherewasno significantdifferencebetweenthelevelof anxietyonthefourthdayandontheseventh day.Inconclusion,multicolorlightingwas foundtoalleviatetheincreaseinanxietyand negativeemotionscausedbyisolationand confinement.Moreover,therandomchange oflightcolorintheisolatedenvironment appearedtohelptheparticipantsgetan increasedsenseofsurprisetocounteractthe monotonyoftheisolation,withaneffect similartothatofcircadianlights.Infuture spaceexploration,coloredlightingorother sensoryadjustmentinterventionscouldbe usedinadditiontoteamworkandcollective lifetoreducenegativeemotionsandanxiety feelings. ■

Accordingtoaseriesofexperiments conductedrecentlyonEarthandduring currentspacemissionsaboardthe InternationalSpaceStation(ISS),NASA believesthatmonotonyofvision,inparticular, aggravatesthecrew’sanxiety,irritability, depression.Moreover,alargenumberof studieshavealsofoundthatcrewmembers onlong-termmissionsontheAntarcticSpace SimulationStationareextremelysusceptible topsychologicalproblemscausedbyvisual monotonyandmonochromaticcolors.Ina researchpaperrecentlypublishedinSpace: Science&Technology,AoJiangfrom EuropeanSpaceAgencyconductedastudy totestwhethermulticolorlightingcanimprove people’spsychologicalstateinanisolatedand conﬁnedenvironmentoveraperiodofseven days.

Besides,thePANASquestionnaire,a self-reportmeasure,wereusedtoassessthe speciﬁcstatesthatemergefromgeneral dimensionsofpositiveandnegativeemotional experiences,andtheGAD-7questionnaire,a one-dimensionalscale,weredesignedto assessthepresenceofthesymptomsof

Prof.GeorgesZISSIS, PhD,SMIEE,Vice-Rector Toulouse3University

ProfessorZISSISwonthe ﬁrstAwardofthe InternationalElectrotechnical Committee(IEC)Centenary Challengeforhisworkon normalizationforurban lightingsystems,theEnergy GlobeAwardforFrance,and theFresnelMedalfromthe FrenchIlluminating EngineeringSociety.Hehas beenawardedthetitleof Professor HonorisCausa of SaintPetersburgState University.

LightingScientistandAuthority, ProfessorGeorgesZISSIS,Toulouse3 University,France

LIGHTINGINTERVIEW PROFESSORGEORGESZISSIS

LEDprofessional: Couldyouexplain yourtwofunctions/organizations: “HeadofLight&MatterResearch Group”and“Vice-rectorforEuropean andInternationalProjects”?

ProfessorGeorgesZISSIS: Iamthe directorofthe“Light&Matter”(L&M) researchgroup [2] attheLAPLACE laboratory [3] thatemploys,onaverage,20researchers:5permanentacademicstaff,3researchengineers(two withPhDs),2post-docand10PhD(I haven’tcountedtheMasterstudents here).LAPLACEstandsfor“Laboratory ofPlasmaandConversionofEnergy”It isacommonresearchunit(UMR5213) betweentheCNRS,theUniversityof Toulouse3,andtheNationalPolytechnicInstitute.Itemploysapproximately 300researchers,PhDstudentsandstaff membersanditissubdividedinto12researchgroupslikeL&M.

TheLight&Matterresearchgroup, undermydirection,isworkingonthe productionanduseoflight.Wefavora holisticapproachtothesystem.Icoined thegroup’sstrategy:consistinginunderstandingthefunctioningofacomplex

system,studyingitscomponentsand theirinteractions,withtheultimateobjectiveofoptimizingthesystemaccordingtoitsapplicationanduse.Toperfect thisoptimization,wecalluponourcompetencesinmodellinganddiagnostics, withoutneglectingtheprototypingand thedemonstrationonalargescale.

InparallelwithmyfunctionasL&Mhead, Ihavea4-yearmandateasVice-Rector ofToulouseUniversity(4,500staffmembersand35,000students)inchargeof EuropeanandInternationalProjects.In thatframe,Iamdeveloping,withthe staffmembersofmyserviceatthecentralInternationalRelationsOfﬁce,anew strategyforouruniversityinordertoincreaseourinternationalvisibilitythrough thecoordination,orparticipation,of large-sizeEuropeanandInternational networkingProjects(INTERREG,Euromed,etc.).Sincemyarrival3-years ago,weobtainedseveralnewprojects, andmyserviceismanagingabudget of2-3millionEuroscomingmainlyfrom Europeanprograms. Ihavesomeotherfunctionsonaninternationallevel.Forinstance,in2021, IcreatedandIamchairingtheIEEE SmartLightingProjectintheUSA [4] andIhavebeenchairpersonofthe4ESolidStateLightingAnnexoftheInternationalEnergyAgency [5] since2019.

GeorgesZISSIS[6,7]isDistinguish-classProfessorinToulouse3 UniversityandDirectorof“Light&Matter”researchgroupofLAPLACE. Hehaspublishedmorethan156papersinpeer-reviewedreferenced scientiﬁcjournals(Hischindex22),morethan300papersininternational conferences.Hehasgivenmorethan90invitedlecturesatinternational andnationalevents.HewasPresidentofthePowerElectronics, Electronics,OptoelectronicsandSystemsectionoftheFrenchNational CouncilofUniversitiesandPresidentofIEEEIndustrialApplication Society.HeisChairmanofthe4E-SolidStateLightingAnnexofthe InternationalEnergyAgencyandIEEESmartCitiesInitiative. ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design

LEDprofessional: What’sthegoalof theIEEESmartLightingProject?

ProfessorGeorgesZISSIS: Thisisa projectthatIinitiatedin2021withinthe IEEEFutureDirectionsCommittee(FDC).

ProfessorGeorgesZISSIS: Igraduatedin1986fromthePhysicsdepartmentattheUniversityofCrete(Greece) ingeneralphysics.ThenIgotmyMSc andPhDinPlasmaSciencein1987 and1990fromToulouse3University (France).

LEDprofessional: Thankyouforthe opportunitytodothisinterviewwith you.Canweperhapsstartbyasking youaboutyourprofessionalbackgroundandhowyoucametothesubjectoflight?

Myrelationshipwithlightingtechnologystartedduringmythirdyearinthe PhysicsdepartmentattheUniversityof Crete(Greece),in1984,whenoneof myprofessors,DimitrisKarabourniotis proposedthatIworkinhislaboratory onthemodellingofthechemistryinside metalhalidehighpressurelamps.Itwas myﬁstcontactwithlightsourcesand itscomplexphysics.Attheendofmy studies,IobtainedaFrenchGovernmentfellowshiptocontinuemystudieswithamasterandPhDinplasma physicsintheUniversityofToulouse [1].Iintegratedtheteam“HighIntensity LightSources”oftheCentreofAtomic PhysicsofToulouse(CPAT).Iworked thereintheframeworkofmyPhD,underthedirectionofProf.Jean-Jacques Damelincourt,onthemodellingofﬂuorescentlampplasma.AfterthatIgot apermanentpositionatToulouseUniversityintheelectricalengineeringdepartmentinthedomainofScienceand TechnologyofLightingSystems,which hadalmost40yearsofhistorybehindit.

PROFESSORGEORGESZISSISLIGHTINGINTERVIEW Issue93/Sept-Oct/2022

Toulouse3UniversityCampus.

TheLightingIndustryandICTIndustryarenowrapidlyevolvingandconverging.IEEEiswillingtoaccompany thisevolution.TheprojectaimsatclusteringIEEEmember’sexpertisefrom varioushorizons(morethan400,000 membersworldwide)anddisciplinesto advanceinthescienceandtechnology ofSmartLightingSystems.Insidethe projectwearenowworkingon,among otherthings,thecreationofaﬂagship conferenceandexpo,awhitepaperon smartlightingandanIEEE-levelcontest (XPrize-like)forsmartlightinginpoorand developingworldregions.Inparallel,we regularlyorganizewebinarsandworkshops.Theseactions,aswellasthe participationintheIEEESmartLighting project,isopentoall,whethertheyare IEEEmembersornot [4]

2.TheCPATmergedwith2otherlaboratoriestoformLAPLACE:thelaboratory ofplasmaandCONVERSIONOFENERGY.Producinglightfromasystemis “ConversionofEnergy”,therewasno longeraneedtostickwithplasmas… ThewaytointroduceSSLwasopenfor me.

ProfessorGeorgesZISSIS: WhenI arrivedinToulouse,theresearchteam HighIntensityLightSources,createdin 1972byProf.Damelincourt,mymentor, wasfocusingonthestudyofelectrical dischargelampsandthatinCPAT,a50year-oldlaboratoryworkingonplasma science.Underthoseconditionsone canimaginethatthearrivalofsolid-state lightingcouldaffectourworknegatively. However,thisdidn’thappen!Thiscanbe explainedbyseveralfacts:

Itconsistsoftheseedingofa‘Smart LightingInitiative(SLI)’thatwillbecarriedoutduringthenext3to5years.The projectisfinancedbyIEEESmartVillage.Itisalsostronglyassociatedwith IEEESmartCitiesTechnicalCommunity.Infact,Lightingfitsperfectlywith theIEEEmissionfor“AdvancingTechnologyforHumanity”becauseartificial lightgenerationisaninherentneedfor humanbeingsandsociety.Itconsumes hugeamountsofenergyandresources, itimpactsourperformance,security, well-beingandhealth,butalsoourenvironmentandecosystem.Lightingisa factorofsustainabledevelopment.

ProfessorGeorgesZISSIS: TheSSL Annexwasestablishedin2010under theframeworkoftheInternationalEnergyAgency’sEnergyEfﬁcientEnd-use Equipment(4E)ImplementingAgreementtoprovideadvicetothegovernmentsofitsmembercountriesseekingtopromoteenergyefﬁcientlighting andtoimplementqualityassuranceprogramsforSSLlighting.Thisinternational collaborationcurrentlyconsistsofthe governmentsofAustralia,Canada,Denmark,France,theRepublicofKorea, SwedenandtheUnitedKingdom.The Annexconstituteaperfectgroundfor developingvariousactivities.Icanrelatetosomeoftheexamples:TheAnnexhavesuccessfullyorganizedand carriedouttwointer-laboratorycomparisons,IC2013andIC2017,where collectively146labsfromaroundthe

worldwerecomparedformeasurements ofLEDlightingproductsusingintegratingspheresandgonio-photometers. TheIEA4ESSLAnnexisnowconsideringwhethertolauncha2022InterlaboratoryComparison(IC2022)for temporallightmodulation(TLM)measurements.Areportpublishedrecently, providesalookacrossthebodyofliteratureonlifetimedeﬁnitionsforLEDsand LEDproducts.Thereportlooksatfailure mechanisms,acceleratedlifetestsand testmethodsforestimatinglifetime,and providessomerecommendations.

MentorsofProf.ZISSIS:J.J.Damelincourt(1939-2008,left)fromUniversityofToulouse3,France,andD. Karabourniotis(1949-,right)fromUniversityofCrete,Greece.

LEDprofessional: Howdidyouexperiencethetransformationtoward solid-statelighting,andhowdidyou alignyourinstitutewiththenewtasks?

1.ProfDamelincourtintroducedthevery ﬁrstideatoextendourdomainofactivitiesfromthedischargelamptothe lightingsystem.Frommyside,Ihad foreseenratherearlytheevolutiontowardsSSLs.

Thereiscurrentlynoagreementasto whichtestmethodcanbestestimate thelifetimeofLEDlightingproductsand thereportthusaddressesakeyissue forregulatorsandindustryinterestedin deploymentofLEDtechnologies.Annex’sexpertsproduceandregularlyupdatevoluntaryqualityandperformance requirementswhichaddressproductattributessuchascolor,lifetime,power, andefficacyforcommonSSLlampsand luminaires.Theproductperformance requirementsofferalimitednumberof performancelevels,agreeduponby IEASSLAnnexmembers,thatcould beutilizedbygovernment,non-profit anddonoragencieswhendesigningprogramsandpolicies.Theobjectiveisto providealimitednumberoflevelsthat canbeutilizedbyprogramdesigners toreducecostsofwritingspecifications andtofacilitateeconomicadvantages forindustry/trade.Lastbutnotleast,AnnexisworkingonLifeCycleAssessment forlightingproductsandalsoonimpacts ofartificiallightingonhumansandour biotope.Icouldcontinuerelatingactions foralongtimebutitwouldbebetterto visitourwebpagetolearnmore.You candownloadveryusefulresources [5]

LEDprofessional: What’stheintention ofthe4E-SolidStateLightingAnnex oftheInternationalEnergyAgency?

3.Intheframeworkofthecreationof LAPLACE(Iwasoneofthe3people thatco-createdanddirectedLAPLACE duringitsveryﬁrst4-years),Idecidedto mergemyoldteamwithanothergroup comingfromtheLGET(anotherofthe3 clusteredlabstoformLAPLACE).This team,called‘organicsemiconductors’, wasworkingonOrganicLightEmitting DiodesandOrganicPhotovoltaics.The L&Mgrouphadbeencreated!

Ombroscopyset-up.Ombroscopyisanoptical techniquethatvisualizesair’srefractionindex variationsduetoconvectiveheatevacuation fromhotspots.Itallowsresearchersto“seethe invisible”.

FollowingthecreationofL&M,ourresearchthemeswerecenteredaround thescienceandtechnologyoflight sourcesandlightingsystems,aswell asthestudyoftheusagesoflightand itsinteractionswiththeenvironmentand society.Thethemesofthegroupare inseparablefromtheapplications.Althoughouractivitiesarestronglylinked toapplications,theydonotneglectfundamentalaspectsintheﬁeldofenergy conversion,materialsandsystems,for lighting.

ProfessorGeorgesZISSIS: TheL&M teamiswellknownandrecognizedin thedomainoflightingsystems.Our visibilityiscomingfrombothacademic andvalorizationactions.Forinstance, mygrouppublishesaround15papers inpeer-reviewedjournals,everyyear andweareregularlyinvitedtogivetalks inimportantconferences,andwecollaboratewithmanyacademicinstitutionsworldwideworkinginthedomain oflightingandlightingusages.Addto thatmorethan90PhDsdeliveredsince 1972.Concerningthevalorizationaspects,beyond12patentsandthesuccessfulcreationof2spin-offs,sincethe creationofthegroupinthe1970’s,we hadtheopportunitytocollaborateona contractualbasiswithallthemajorlightingmanufacturers,worldwide.Today thisactivityisampliﬁed,forinstance,in thedirectionofHigh-TechSMEsonboth nationalandinternationallevels.Ourvariousindustrialcollaborationsconsumed morethat10millionEurosinresources eitherfromnational,European,internationalprojects,ordirectlyfromindustry.

LEDprofessional: WhatarethepossibilitiesofcollaboratingwithLaplace UniversityinToulouse,bothfromaresearchpointofviewandforpossible industrialcollaborationpartners?

scoreespeciallyunderpandemicconditions.Thedelegatescamefrom36 countriesdistributedthroughout5continents.Roughlytwothirdsofthedelegateswerefromacademiaandvarious organizationsandonethirdwasfromindustry.

Whitelightinvestigationsareperformedin LAPLACEbyexposingyellowphosphortoviolet laserdiodes(1.8Winthisset-up).

ProfessorGeorgesZISSIS: TheInternationalSymposiumontheScienceand TechnologyofLighting(LS-series)always aimstoprovideanexcellentforumfor scientistsandengineersworldwide,in bothacademiaandindustry,toshare andexchangethelatestprogresson theScienceandTechnologyofLightingSystems.TheLS-serieshasamore than45-yearhistoryandsincethe1st LS (LS:1)in1975inLoughborough,United Kingdom,ithasbeenheldregularlyin2 or3-yearintervalsonvariouscontinents. Theeventwassupportedsubstantially bythelegacylightingindustryandthe qualityofpaperspresentedinthevariousLSmeetingswas(andstill,is)very high.Notethatoneoftheﬁrstpublic blueLEDdemonstrationsbyShujiNakamuratookplaceduringanLSmeeting inGreifswald,Germany.Therewere460 peopleinattendanceatthatmeeting. Especiallyforthistime,the17th LSin Toulousehasbeencollocatedwiththe 11thInternationalConferenceonEnergy EfﬁciencyinDomesticAppliancesand Lighting(EEDAL).Globally,wehad263 attendees(148in-personand115in remotemode)foraglobalnumberof 149papersaccepted.Thisisaverynice

LEDprofessional: Let’sdiscussthe InternationalSymposiumontheScienceandTechnologyofLighting.Can youpleasegiveussomebackground onthehistoryanddevelopmentof thisevent?

Thisclearlyillustratesthesincerewillof L&Mtoworkhand-in-handwithindustryandanyotheractorinthedomainof lightingsystems.L&M,beyondvarious resources(set-ups,staff,databases), hasawideareaofexpertiseinthedomainoflightingthatisalwaysvaluableto ourpartners.Thisis,inmyeyes,a“winwin”situation.

DuringthetraditionalsteeringcommitteemeetingwedecidedtotransferLS toIEEESmartLightingandtransformit inaﬂagshipannualevent,keeptheLS acronymandchangethenameof“IEEE SustainableSmartLightingWorldConferenceandExpo”(thisisnotdeﬁnitive), thepiloteventwilltakeplaceinBombay inJune2023.

OLEDproductionset-upinL&MgroupLAPLACElaboratory:(fromlefttoright)evaporator,RFsputtering,andtestingunitincommunicatinggloveboxes. PROFESSORGEORGESZISSISLIGHTINGINTERVIEW Issue93/Sept-Oct/2022 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design 23

d.Trainingoflightingprofessionalsin themodernlightingtechnologiesand associatedconstraintsisahardpoint. Today,manyexistingtrainingprograms forlightingprofessionalsareoutdated andneedtoberefurbished.

a.Researchonlegacytechnologiesis stilltherebutwithoutanyconcreteindustrialfuture.However,foracademics manyinterestingfundamentalquestions needfurtherexploration.

ProfessorGeorgesZISSIS: Based onthevariouspaperspresentedatthe LS,itisindeedpossibletooutlinesome trendsforthefuture:

deleteriouseffect.Withmoreenergyefﬁcientproducts,pricesdecreasewith technologymaturity(SSLsystemsinour case),andtheconsumersaretempted toaskformoreoutcome(light).Thisanarchicgrowthleadstotheannihilationof allenergysavingslinkedtotheonlyefﬁciency,andthatinlessthanadecade. Thisisthefamous“rebound”effectas describedbyJevonsin1865,calledalso “Jevonsparadox”.SmartLightingsystemscanhelptoavoidtheeffectsofthis paradox.

c.SmartLightingSystemsandassociatedservicesarethefuturedirections

futureoflightingeneralterms.What directionsfortheworldoflightcan youidentifyand,byextension,what willyoubeworkingonintensivelyin

ThenitwasdecidedtohavetheLSin ahybridformat:bothin-personand remoteparticipation.Thisimpliedadditionalconstraintsbecauseallsessions(upto5parallelsessions)hadto bebroadcastinreal-timeforremote participantsandrecordedforaccessingthemremotelyandkeptavailable fortwomonthsaftertheconference. Fortunately,IEEEgaveusaccesstoa specializedplatformtosupportthathybridevent.AlthoughthehybridLSoutcomewasasuccess,bothscientiﬁcally andﬁnancially,(thankstomyresearch teammemberswhoworkedveryhard), Icansaythattheorganizationforahybrideventisa“mesh”andI’llneverdo itagain.OrifIhavetheobligationtodo so,I’llaskforaregistrationfeemuch moreexpensiveforremotethanforinpersonparticipants).

ProfessorGeorgesZISSIS: Energy priceswillincreaseinexorablyandrapidly, ifnotexponentially,duringthenextfew years.Unfortunately,therearenoactionsthatcanchangethattendency. Electricallightingabsorbs13-14%of theannualelectricitygeneratedinour planettoday.Alargepartofthatenergyisstillspilled.Smartlightingcan helptosavespilledenergy.Ofcourse, anyenergysavedreducesthebillofthe end-userseveniftheenergy’spriceis increasing.However,wemustbevery careful.Usingmoreenergyefﬁcient productswithoutanylimit,mayhavea

ProfessorGeorgesZISSIS: Thedirectionthatwillbetakeninthenextyears isclearlysmartlighting,whateverthe lightsourceitselfwillbe.Micro-LEDis definitelyatechnologythatwillallow somenewperformanceslikeflexiblelight sourcesthatLEDscan’tachieve.White lightcreatedfromRGBmicro-LEDsis expectedtoachievehigherluminousefficaciesthanphosphorconvertedLEDs, butthegreengapisstillthere…OLEDs areflexible,foldableandtheydon’tsuffer fromgreengap.However,manyproblemsneedtobeaddressedbeforethe technologybecomesmatureforgeneral lighting.Micro-LEDscanjamthisprogression.Laserlight,canconstitutea validsolutioninthecaseofhighcurrents andhighluminousfluxes.Itisincreasinglybeingadaptedforbeingcoupled withinformationtransferviaVLC,which isoneoftheflagshipcharacteristicsof smartlightingsystems.Moreexperience inthedomainisneededtodecidethe pathtofollow.

LEDprofessional: Let’sdiscussthe Toulouseoverthenextfewyears?

ProfessorGeorgesZISSIS: Corona, hadacertainimpactontheLSorganization.Theconferencewaspostponed fromNovember2021toJune2022in ordertodrawin-personparticipants becausethisthe“signature”andthe “essence”oftheLS-series.

LEDprofessional: Whatcontribution canthelightingworldmakeconcerningtheglobalriseinenergyprices?

LEDprofessional: Whattopicswere discussed?Andwhichoneswerein theforeground?Canyoudetermine trendsforlightingresearchandthe lightingindustrybasedonthisevent?

LEDprofessional: TheLS2022recentlytookplaceinToulouse.What wastherestartlikeaftertheCoronarelatedbreak,andhowdiditgooverallfortheorganizer?

LEDprofessional: Whatdirections willthenewlightsourceslikeLED, OLED,Micro-LED,take?Willlaser lightbeanissue,orhowdoyousee thebioluminescencelightsources?

FourgreenOLEDsmadeinL&MLAPLACE–40%ofthematterusedintheOLEDstackis bio-sourced(β-Carotene). 3DreconstructionofanLEDcomponentinan LEDlampusingX-raytomography.Awayto investigatedefectswithouthavingtointervene.

togo.Socialissues,environmentalimpacts,includinglightpollution,needto beaddressed.Lightingeconomicsand lifecostassessmentarerisingaspects.

b.LEDtechnologyisfullymature,associatedmetrologyandstandardization aspectsareactivelyaddressedwithsuccess.Newtechnologies,likeOLEDs, solidstatelasersarearoundthecorner but,difﬁculttosaywhattheevolutionwill be.

[6] Prof.ZISSISonLinkedIn https://www.linkedin.com/i n/georges-zissis-9b88887/

References

Developinganewmetricsthatcanquantifythe“efﬁciency”,“sustainability”and “affordability”ofasuchsystemisa cross-disciplinesubject.Apartofmy teamisworkingonthisaxis.Inparallel,wecontinueoureffortstoproduce OrganicLightEmittingDiodesbasedexclusivelyonbio-sourcedmaterials.Just imagineanOLEDusingmoleculesfrom

carrotsandalgae,exemptfromITO.This isnotscience-ﬁction,butforthemoment,Ican’tsaymoreforobviousIP reasons.

ProfessorGeorgesZISSIS: AsImentionedbefore,myteamhasprivileged collaborationswithvariousacademic institutionsandindustryworldwide.Further,IEEESmartLightingoffersanexcellentbasisforstructuringsuchcollaborations.However,wearefullyopento newcollaborationswithintheindustry inthedomainsoforganiclightemitting componentsandlightingsystemquality andefﬁcacyenhancement.

[5] 4ESolidStateLightingSSLAnnex https://www.ie a-4e.org/ssl/

[4] IEEESmartLightingProject https://cmte.ieee.org/fu turedirections/projects/smart-lighting/

LEDprofessional: Thankyouvery muchfortakingusonthisexcitinglightingjourneyandgivingusa glimpseintoyourextensivework.

ProfessorGeorgesZISSIS: Wewishto thankLEDProfessionalfortheopportunitytogivethisinterview. ■

[1] ToulouseIIIUniversity https://www.univ-tlse3.fr

LEDprofessional: Whichteamorresearchgroupsareavailabletoyoufor this?Wouldyoualsobeinterestedin industrypartnersinspeciﬁcareas?

[7] Prof.ZISSISonCVArchives https://cv.archives-ouv ertes.fr/georges-zissis

ProfessorGeorgesZISSIS: Tome, therightdirectionforlightingistoput thestressonSustainableDevelopment andAffordabilityissuesexploringSmart Lighting’scapacities.

AsfarasI’mconcerned,thiscanbe achievedthoughtheSSL2 conceptthat Icoinedrecently:“SustainableSmart Lighting(1st SSL)systemusesandoptimizes,inanintelligentway,thebest existingtechnology.SolidStateLighting(2nd SSL),tobestfulﬁlpresentneeds forartiﬁciallight,andreduceundesirable side-effects,withoutcompromisingthe abilityoffuturegenerationstoinnovate.” Thismayleadtoasmartsystemthat lights-upsmart,inasustainable&affordableway,whereitisneeded,whenitis necessaryandasgoodaspossible!

[2] Light&MatterResearchGroup http://www.laplace. univ-tlse.fr/Lumiere-et-Matiere

[3] LAPLACELaboratory http://www.laplace.univ-tlse.fr

• Newsletter:15,000

LightingDesignChannel

Theauthorsofcontributionsacceptedby theprogrammanagementwillbeinvitedto giveapresentationand,ifappropriate,to writeaqualiﬁedarticle.Eachpresentation willbeannouncedtotheindustryand/or designchannelcontactsandfollowers immediatelyafterpublication.

LiketheLEDprofessionalSymposium +ExpoandTrendsinLightingForum&Show thattookplaceattheFestspielhausinBregenz/AustriaeveryyearsinceSeptember, 2011,LpSDigitalismeanttoapproach andsupportthecompletevaluechainin thegloballightingindustry.Whenitcomes toTechnologicalDesign,LpSDigital’sgoal istoprovideCorporateManagment,TechnicalManagement,R&DandProduction/QMwithinthegloballightingmanufacturingindustrywithtopnotchtechnical knowhow,primarilyonacomponentlevel. IntermsofLightingDesign,LpSDigitalwill showbestpracticeforArchitects,LightingConsultants,ElectricalConsultants, LightingDesigners,LightingOEMs,IT/IoT SystemIntegratorsandstudents.TheeditorsfocusonHumanCentricLighting, ConnectedLighting,SmartControls,InternetofThings,LightasaServiceandmuch more.

VIRTUALEXHIBITION

LpSDigitalistheuniqueandﬁrstdigitallightingconferenceand exhibitionavailabletoviewers24hoursaday,7daysaweek.LpS Digitalpresentscurrent,high-qualitycontentaboutlighting technologies,designandapplications,andacquaintstheviewers withthelatesttrendsinproductdevelopmentsandapplications.

• Twitter:22,000

LightingIndustry& TechnologyChannel

• LinkedIn:4,600

• LinkedIn:11,700

WiththeIndustry/Technologychannel, over30,000contactsinthelightingsector aretargetedandaddressed.Theopt-in databasesarehighlyselective,highlyqualiﬁedandaddresskeypersonsintherespectivechannel.

ExperiencetheFutureof Light

VIRTUALCONFERENCE

LPSDIGITAL LPSDIGITAL:THEFIRSTDIGITALLIGHTINGCONFERENCE&EXHIBITION 26

• Magazine:30,000

• Newsletter:27,000

• Global,highly-qualiﬁedtargetgroup Knowledgetransferatahighlevel Idealplatformforexpandingthenetwork

•

Issue93/Sept-Oct/2022

BeneﬁtsforVirtual Exhibitors

• Immediatepromotionofinnovationsand novelties

• Online:5,000/month

• Highlyefﬁcientpromotionatnorisks

• Magazine:30,000

Virtualexhibitorshavethepossibilityto presenttheirproductsand/orservices.The maximumlengthofthepresentationis20 minutes.Eachproduct/servicevideois announcedtotheindustryand/ordesign channelcontactsandfollowersimmediatelyafterpublication.

BeneﬁtsforConference Authors

LpSDigital:LightingConference& Exhibition2022

• Online:30,000/month

•

• Global,highly-qualiﬁedtargetgroup

WiththeDesignchannel,over30,000contactsinthelightingsectoraretargetedand addressed.

UniqueGlobalReachin theLightingSector

• ParticipationintheLpS/TiLAwards

LightingforResidentsandfor Architecture

LocationandArchitecture

TheTiffanyhouseissituatedatthenew PortReclamationAreaontheMacau Peninsula.Thebuildingriseselegantlyand naturallyfromtheexistingstreetscapesof oldMacau.Itrepresentsanewluxuryretail andresidentialdevelopmentthatresponds sensitivelytothetraditionsandscaleofthe existingurbanpattern.Italsooffersabold newdirectionandauniquearchitectural signaturetotheskylineofMacau.Witha 3,800m2 footprint,thesiteissituatedin avibrantpartofthecity,justoppositethe PolytechnicInstituteatthecornerofRua deLuisGonzagaGomesandRuadeXiamen.

LuxuryResidence

markwhilstpreservinganuninterrupted viewandavoidinglightnuisancecreatedby lightpollution.Toachievethis,fixturesare recessedinthefaçade.Lightspillislimitedwhileaconsistentvisualappearance fromthepedestrianviewpointandatdistanceisachieved.Continuous,static,and monochromaticlinearfixturesoflowintensityareflushmountedalongtheouteredge ofthevolumetocreateaseamlesseffect alongtheframe,creatingthisveryjewelry boxwrapping.

Lichtvision’sconceptfortheinteriorspaces oftheTiffanyHouseconsideredtwoapproaches.Lightshouldcomplementthe interiordesignbyseamlesslyintegrating intothearchitecturalfabric.Atthesame time,lightshouldbestandingoutandcelebratingitselfasanindividualdecorative elementateyelevelwiththearchitecture. Throughoutthespaces,acombinationof directandindirectlightingcomponents wasapplied.Thelightlineasastrongand recurringgeometricalelementwasapplied promotingvisualdirectionandguidanceas wellascreatingsoft,omnipresent,andverticalilluminance.Linearformsreacttothe interiorelementsbyaligningorwrapping aroundthemorbydeliberatelycrossing them,makingitselfvisuallyapparentand outstanding.Toaddcontrastandhierarchy,directlightingcomponentswerepreciselyplacedindividuallyorinclusters.Especiallylounges,F&Banddiningfacilities, experienceagreatamountofdecorative lightingelements,creatingthisveryliving room-likecharacteristicofsparkleanda cozyatmosphere.

Lichtvisiondevelopedalightingstrategy byfeaturingthearcadesasatimeless, metropolitanexperience.Largescale, custom-madependantfixturescomplimentthearchitecturalrhythmofthecolonnades.Thefixturesfeaturediffusecylinders ofhomogeneouslightforarecognizable imagefromafar.Atcloserange,theelegantpiecesinteractwiththemirrored ceiling,creatingavisualextensionanda vibrantinterplayofbrilliancewhenpassing by.Theluminairesweredevelopedtowithstandsubtropicalweatherconditionse.g. extremewindduringtyphoons.Tomeetrequirementsonconcerningilluminancesand uniformities,adirectlightingcomponent atthebottomofthependantssupplyadequatelightinglevelstothefloor.Apublic retailpathcrossesthebuilding.Although functionallyatransitionalspace,lighting wasaddedontocreateapointofinterest forthepublictorevelin.Overalllighting levelsaresettoahumanscaletointegrate withtheexistingsurroundingarchitectural contextwhilestagingtheretailshopsinthe rightambience.

InMacau,localplanningauthoritiesrequire agreatamountofconnectivityofnewdevelopmentswiththeremainingcity.Therefore,aconsiderableportionofthebuilding hasbeendedicatedtopublicuse.Broad coveredfootpaths,traditionalforMacau’s colonialheritage,surroundthebuildingon allfoursidesaswellasaretailunderpass thatcutsrightthroughthebuildingactas naturalconduitsfromonepartofthecity toanother.Pedestriansinteractwiththe architectureonapersonallevel,sheltered fromtheburningsunduringthesummeras wellasendlessrainduringwetseasons.

LichtvisionDesign

TiffanyHouse

Thearchitecturalvolumeisorganizedbya seriesofinterlockingelements.Inspiredby staggedjewelryboxeswherethedrawers arepartiallyopen,andtheobserveranticipatesgoinginsideforalook.Façade lightingactsasaframe.Justlikeagift, thelightwrapsaroundthefacetlikearibbonaroundthejewelrybox.Highlighting theframesputsanemphasisonthearchitecturalvolume.Theframesturnintothe focalpointsduringthenightasopposedto theobviousverticalrunningﬁnsduringthe day.Theinterlockingvolumescreatelandscapedbalconiesandterracesatvarious levels,providingwideangledvistasacross thecityandharbor.Asfaçadelightingand residentsareatcloserange,thelighting designhadtoconsiderthehumanproximityanddailyusagebyresidentsaswell asthearchitecturalgesture;thebigpicture.ThechallengeforLichtvisionwasthe splitbetweencreatinganight-timeland-

CreatingConnectivity

Typology: PrivateResidential& Commercial ScopeofWork: Façade,Interior& LandscapeLighting Start/Completion: 2016/2021 Location: Macau,China Size(GFA): ≈ 46000 m2 Client/Owner: ChinaStarEntertainment Tenant/User: Private/Corporate ProjectLead: LichtvisionDesign;Clemens Seipelt,SunniaCheng,DonaldMa, CrisBatula Architect/Designer: Arquitectonica (DesignArchitect),LWK+Partners (ExecutionArchitect) Photographer: QiShuoqian,Copyrights

Withitsdistinctivemultipleboxdesign, TiffanyHousehasbecomethelatest, excitingnewlandmarkontheskyline ofMacau.Itisastate-of-the-art,highendmixed-usedevelopmentofaround 46,000m2 GFAandconsistsofathreestoreypodium.Itprovidesretailat streetlevelaswellaslobbies,aresidentialclubhousethatincludesaspa, gymandfoodandbeverages.Thetwo residentialtowersat60mheighteach featureluxuryapartments.Lichtvision hascreatedaholisticdesignlanguage fortheinteriorsandexteriors,includingthefaçade,publicinteriors,andthe landscapedareasofthedevelopment.

http://www.lichtvision.com

Subtlelinearlightingemphasizestheinterlocking volumesofthebuilding.Thetwoplayfultowersare beingheldbyarigidcolonnadepodiumfeaturinga rhythmicpatternoflargescalependants.

Thelightlineasarecurringtoolemphasizingrhythm anddirection,connectingthearchitecturalintentwith theinteriors.

Theclubhouseatpodiumlevelfeatureshigh-end loungeandF&Bfacilitiestotheresidentspromotinga playfulanddecorativelightingapproach.

Thelightlineenhancinginteriorarchitectureby integratingintoitsfabricorbydeliberatelyignoringit tostandoutandcelebratingitself.

Dipl.DesignerWilfriedKURZ,MLL,BartenbachResearch& Development,Austria

Figure 4 showsdifferentperceptionsof aroom:thelightingsituationdoesnot change.Theremission(spectralreflectance) ofthewallsdefinesthewhitebalance, whilethesurfacestructureaddsinformation.Bartenbachcompletedextensive studiesonambienteffectsandthereisa significantincrease(ordecrease)ofwellbeingandperformancewithchoosinga (non)matchingsurface(Figure 4).

Theorderoftheday,ineverydaylife,is nottothinkaboutwallsandtheirrelevance.Wallsareusefulforhanging clocks,mirrors,TVsandpictures.The thingsthatwewanttolookatcanbe highlightedandgivetheroomarecognizableidentity.Butthebasicfunction ofawall,aspartofthearchitecture,is tocreateanartificialspacebyseparatingtheoutsidefromtheinside.This cannowbeconditionedwithtemperature,humidity,acousticsandbrightnesstocreatecomfort.Wethenselect awallcolor,wallpaperortexturedwall covering,oroptforexposedconcrete. Thiscombinesthevisualidentitywith thesensationofthespaceandcreates anothertypeofcomfortasthebasisof visualperception,aswewillsee.

Thereplacementofconventionallight sourceswiththeLED,hasnotonlychanged lightingtechnology,butalsocreatedopportunitiesforhowtoworkwithartificial light.Technicalfreedomsallowastrong focusonarchitecturalqualitiesandthelight sourceintegratesitselfmuchmoreintothe architecture.Theluminairebecomesmore andmoreinvisible,butstillperfectlyilluminatesthewallortheobjectonthewall. Thebasiclightingtasksremainthesame, whetheritissomethingonthewall,likea painting,orthewallitself.Weusuallydon’t focusonthewallitself,sotherelevancein perceptionofspacedefiningverticalilluminationisbrieflyshown(Figure 1) [1]

ThePerfectWallwasher

Theexampleimagesofthedisplayed paintingweretakeninautomaticmode, andforthebestresultwewouldadjust theexposureparameters(Figure 2).Perceptionworkssimilarly,adaptingthevisual processtothefocusedtask.Ataphysiologicalstartingpointofthis,thecontrast sensitivity(abasicvisualfunction)isoptimal ifthefocusedtask(centerluminance)has ahigherluminancethantheambientﬁeld (Figure 3) [1]

Awallthatappearshomogeneousisnot evenlyilluminatedoveritstotalheight. Studiesformuseumlightingshoweda threetimesbrighterupperarea(Figure 6). Iftheratioisabovethis,thewallappears unnaturallyﬂat,likeawalloffog.Downto anapproximateratioof10to1,thewall isperceivedasfullyilluminated.Below that,theupperpartstartstodominate. Lightingat 30◦ totheverticalcreatesan optimalmodellingeffectforexhibits.Wallwashingcanbesomewhatsteeper,butthe lightdistributionmustbedesignedforthis (Figure 6).

Figure3: Thecontrastsensitivityisoptimalifthe centerluminanceishigherthantheambientone (stableperception)[1].

VerticalIllumination

PerceptionofContrast

Figure2: Thelightinglevelofthevisualtaskand thewallisconstant.Onlythedifferentdegrees ofreﬂectionofthewallleadtodifferentcontrast ratiosandperceptualqualities.

Figure1: Threetypesofverticalbrightnesshighlightingaccentuating,wall-relatedplanarand self-luminous.

Inconsequence,twodifferenttypesof lightingconceptsaremeaningful.Conventionalpoint-shapedspotlightswithrotationallysymmetricallightdistributioncreate parabolicfigurationsonwalls.Traditionally, (halogen)incandescentbulbsinvarious designsorhigh-pressuredischargelamps servedaslightsources;linearlightingsystemswereimplementedwithfluorescent tubestogeneratelargebrightsurfaces. Nowadays,theadvantagesofspectral qualityandefficiencyofconventionallight sourceshavelongsinceceasedtobea categoricaldecisionintheplanningprocess.WiththeuseofLEDs,theyhave becomepreciselyplannableandtargeted properties.

Figure4: Coloredandstructuredwallsprimeour perceptioninasubliminalway.

Unfortunately,diffuseaccentlinesformain lightingareoftenoversizedatthisceiling positionclosetothewallandthenform aglaringlightchannelwithoutarchitecturalqualities.Theupperpartofthewall hasanimportantroletoplay.Aformally aestheticinterplayoflight,luminaireand architectureisdesired.Besidesaminimizedappearanceoftheluminaires,the

Figure5: (top)TheSemperGalleryinDresdenfeaturesbalancedcontrastandcolortoachievethedesired perception.(bottom)TheStaatsgalerieinStuttgartchangestheperceptionofspacethroughdifferent brightnesses,contrastsandcolors.

Theclosertheluminaireistothewall,the longertheshadowswillbe.Thequalityof thewallplaysanimportantrole.Unsightly wavesofthehastilyconstructedcast-inplaceconcreteshellquicklybecomevisible,muchtothedispleasureoftheclient andarchitect.However,ifthevisibleeffectsaredesiredandthewallisprovided withanappropriatelystructuredsurface, wallgrazersareused.Theiropticsaredesignedtosweepacrossthewallatavery shallowangle,creatingahigh-contrast, three-dimensionalrelief(Figure 7).

Figure6: (left,right)Perceptualstudiesforvisuallyuniformilluminationofwallsindicatealuminanceratioof threetoone.(middle)Thewallisilluminatedwithawallwasherplacedtooclose.Awallgrazeroffers optimizedlightdistributionforsuchapplications.

Figure7: Wallgrazersmodelparticularlyplastic.

wallshouldbeilluminateduptotheupperedge,nolighttracesshouldappearon theceiling.Forthispurpose,thelighting technologymustbecompletelyinstalled intheceiling.Protrudingpartscreateundesirablehalosduetoscatteredlight.The planningpropertiesdescribedsofarcan,in

principle,beachievedusinglinearoptics, butthesecanonlydirectthelightprecisely inthetransversedirectiontothewall.For light-directingpropertiesinthelongitudinaldirection,individualopticsareassigned toeachLED.Thispointlightsourcealso controlstheradiationinthelongitudinal

WithhighluminousﬂuxesfromCOBsizes ofupto15mmfromthelargeversion, multi-storywallheightscanbeilluminated

Figure9: (top)Downwallreﬂectorsareavailablewithdiametersof80,40and13mm.(middle)Pinhole downlightanddownwallwith13mmvisiblediameter.(bottom)Thestoreasastage.Visualcomfortwhile buyinggoods,brilliantlightwithouttheusualglareoftoomanyspots.

Figure8: Theadjacentdownlightsareswitched offtovisualizethemodeofaction.

Preciselightdirectingandglarecontrolare determinednotonlybythereﬂectorgeometry,butalsobyapatentedmicro-faceted surfaceconsistingofcomplexfree-form surfacesthatsuperimposethedesiredlight distributionseveraltimes.Thisensures optimumcolormixingforanydynamic colorapplicationssuchasTunableWhiteor RGBW.Furthermore,itenablesapplication conceptsthatgobeyondimmediatespatial allocation.Twoexamplesaregivenbelow.

Forasmoothtransitionfromahorizontal toourverticalillumination,thedistribution ofadownlightandawallwashercanbe combined.Thisoptic,calledDownwall,is idealforgenerallightingofcorridorsand rooms(Figure 8).

WallandMore

direction,which,forexample,allowsfor radiationlimitationinordertoavoidglare.

Modelinghasavisiblybetterquality,since longitudinalshadowsarenowalsocreated.Theendofawallcanbedeﬁned moreprecisely.Glareispreventedinthe longitudinaldirection,soitisusefulforall wallswithopenends,suchascorners,that allowaviewintothelightingsystemwhen passingby.Toallowpointlightsourcesto blendsmoothlyintoeachother,thelight distributionneedsasoftbutdeﬁnededge. Thisisalsoanadvantageforlightingdesign becausetheluminairespacingbecomes variable.

Figure10: Smoothtransitionsandsoftfadesforhigh-qualitycolordynamicbackgroundsonstagesand studios.

whilethesmallversioncanbecombined withapinholedownlightinthesame 13 mm diameterforasophisticatedinteriordesign (Figure 9).

Theprinciplewasalsoappliedtoaroomin-roomsystem [6].Preciselightdistributionsandoptimalglarecontrolenable avarietyofusagescenariosandalight showerforbiologicalactivationon 2 m2 (Figure 13).Theapproachresultsinqualitativelycoherentlightingconceptswith roomandworkplacespeciﬁcluminaires thatcannotonlycombinetheaforementionedﬂexibilitywithstandardsandenergy requirements,butalsorepresentagainin spatialintegration.

TheTechnologicalWall

Modernopticsmasterthemilieu-deﬁning propertyofglarelimitationtoahighdegree. Usinglightonlywhereitisneededcreates spaceswithahighqualityofperception andthusofstay.Verticalsurfacesarein thevisualfocusofpeopleanddetermine spatialqualitiesevenmorethantheceiling.

Reﬂectivesurfacesarecharacterizedbya moreorlesstechnicalappearance,whose charactershouldmatchtheinteriordesign. Anotherexamplecombineslightingand visualrequirementsandaddsadematerializingeffectthatremovestheperception ofaroomlimitingwall.Toachievethis, asilkymattealuminumpaneliscovered

Figure13: Room-in-Roomsystem.

Thetooltoselectivelyilluminatewallsurfacesisnowthebasisforfurtherimprovement.Thelimitingfactorisnowthewallitself,whoseusualcoloredpaintscattersthe incidentlightbackintoadiffusesoup.A decorativetextureincreasesthewall’sappearance,butnotthequalityoflight.This canbeimproved,andvariousapproaches havebeendevelopedovertime.Awallcan beprovidedwithaphotometricsurfacefor directionalreﬂectionintotheroom.Inthis way,higherverticalbrightnessiscreated andvisualtaskscanbeilluminatedinatargetedmanner.Thehighluminanceofthe LEDscangivethewallabrilliantcharacter (Figure 14).

Inordertomaintainthepositiveaspectsof anopen-planoffice,suchasmobilityand flexibility,andtousethemprofitably,the acousticallyeffectivedivideratthedesk wasusedasaninstrumentforthelighting designintheEUprojectRepro-Light [2,3] ThePersonalTableLight(PTL) [4,5] isa lightingsolutionforvisualandbiological light,whichcanbecontrolledseparately andpersonalizedbytheuserthemself (Figure 12).Thehighbiologicalbrightnessforalightshowerisrealizedinawhite modeaswellasina 490 nmcyanmode.

ThePersonalWall

Thisbecomesclearintheopen-planofﬁce. Room-in-roomconceptsreplacemissingwallsandcreatespatialstructureand functionality.Butjustaswiththefurniture oracousticconcept,acoherentlighting conceptisneededthatisorientedtothe visual,biologicalandemotionalneeds ofpeopleinordertocreateaconsistent activity-supportingmilieu.Visualactivities canbesolvedbyassigningaluminairetoa visualtask.Forbiologicallyeffectivebrightness,lightandsurfaceshavetointeract.

Figure12: TherearpanelofthePersonalTable Light(PTL)servesacousticandbiologicalpurposes.

Figure11: TwotimesfourLEDspectrainred, green,blueandroyalblue,respectivelycyan, amber,2200Kand6500K-theDalisCyclight createshighintensitiesinawidevarietyofpastel andsaturatedcolors.

Theextensivestudiesshowanincreasein userwell-beingandperformance.

Furthermore,excellentshelfspotlightscan berealized,whicharemounteddirectly undertheusuallyhighceilingandthenilluminateonlyshelfareasincludingadjacent visualtasks.Thisapproachisreminiscent ofstagelighting,andthetheatricalcharacteristicscreateafocusedandhigh-quality environment(Figure 9).Stagelightingdesigners,themselves,alsoappreciatethis perfectlightcontrolforplanarlightinhigh precision(Figure 10, Figure 11).

Wallsverymuchinfluencethecharacterof aroomandverticalbrightnesscontributes significantlytothequalityofstay,notonly inabiologicalcontext.Theyarepartofthe subconsciousbaseforapleasantstayand goodartificiallightcanalsocompensatefor architecturaldeficits.Daylightiscertainly thefirstchoice,buttheexamplesshown abovearemorethansupplementarysolutions.Theadvantagesofartificiallightand daylightcanbecombinedtocreateunique solutions.Theseservethedemandsof holisticlightingdesignforvisual,biological

andemotionalqualitiesandtheirbeneﬁts forpeopletoahighdegree. ■

[6] MHouse(xchangedesignGmbH).

withamesh-liketexture.Underﬂatviewing angles,thevisualappearanceissoftand white(coloredversionsarealsoavailable) likeanormalwall;indirectview,adepth effectiscreated(Figure 15).

[2] Repro-Light. https://www.repro-light.eu/ bzw. https://twitter.com/Reprolight

[3] Repro-light:DieLeuchtederZukunft-nachhaltigin ProduktionundNutzung.online:Licht2021.

Figure14: Thewallcanbecoveredwithtexturesthatreﬂectthedirectionalirradiation.

[1] SCHUMACHER,R.O.(1940):„DieUnterschiedsempﬁndlichkeitdeshelladaptiertenmenschlichen Auges“.Dissertation.TechnischeHochschuleBerlin.

References

[5] BartenbachGmbH.PersonalTableLight.[Online] 2020. https://www.youtube.com/watch?v=XdYouJ sOV7U

lightfromawallgrazerisdirectedtowards theviewer.Theprominentimpressionis wellsuitedforperipheralapplicationsin lecturehallsorsimilarspaces.Aesthetically modiﬁedvariantsprovideinteriordesigners withanatmospherictool(Figure 16).

Theaboveexamplesdeliberatelypickup onthephotometricandvisualpropertiesofanothertypeofverticalsurfacein rooms:thespatialopeningsofwindows andglassfronts.Theseincludehighluminance,directionallightincidence,anda space-expandingeffect.Thus,weareina classofhybridsthatderivetheirqualities notfromsolidwalls,butfromtheircounterpart.Inparticular,thedirectionalradiation distinguishesthesesolutionsfromsimilar approachessuchaspixelscreensordiffuselightwalls.

Anotherexamplesimulatesawindowora glassfront.Thewayitworksissimple:the

[4] WirkungeinerpersonalisiertenBeleuchtungmit „Lichtdusche“.W.Pohl,bauaBerichtzum11.SymposiumLichtundGesundheit

Figure15: Areﬂectivealuminumplatecoveredwithamesh-liketexture.

Figure16: Theundergroundimpressiondisappearsthroughthevirtualroomopening. VERTICALILLUMINATIONLIGHTINGDESIGN Issue93/Sept-Oct/2022 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design 41

ImageCredits: Bartenbach,except:ContrastSensitivity–R.O.Schumacher,SempergalerieDresden–LotharSprenger, Wallgrazer–unsplash-MateuszBuda, Shoplighting–XALSquadroatOasis Store-DanPrestonStudio,Stagelighting –RobertJuliat/DalisCyclight,Room-inRoom–Xchangemhaus/DanielKorb, RestaurantatQuellenhofMerano–Helmut Pierer.

BartenbachGmbH isanengineeringofficeindependentofimplementingcompaniesanddealswiththeconception,planningandrealizationofdaylightandartificial lightingtechnology,modelconstruction andsystemdevelopmentofluminairesand luminousceilingsystemsaswellasdaylightelements.Thankstobestnetworking inthelightingindustryaswellasin-house researchanddevelopmentdepartment,it ispossibletosolvehighlydemandingproblemsindaylightandartificiallightingdesign.Weservelightingindustrycustomers, researchpartnersandclientsworldwide whowanttouselighttogenerateadded valueintheirbusinessareas,andwework closelywitharchitectsandbuildingowners.

Author:Dipl.Des.WilfriedKURZ,MLL WilfriedKURZgraduatedasaproductdesignerandworkedforarenownedlighting manufacturerintheﬁrstfewyearsafter graduation.Followingthathewasselfemployedwithastudioforlightandluminaires,whereheacquiredabroadand deepwealthofexperiencetogetherwith otherprofessionalsfromartandtechnology.Amaster’sdegreeattheBartenbach academyroundsouthisareasofexpertise. Since2015,hehasbeenimplementinghis networkedthinkingintherelationshipsbetweenpeople,light,spaceandproductin theresearchanddevelopmentdepartment atBartenbach.

SimulatingtheDaylight Cycle

AmongtheprincipalconceptsofHCLis replicatingthenaturaldailylightingcycle, knowncommonlyascircadianlighting. Simulatingthesun’sdailylightingcycle (andstimulatinghumanipRGCs)requires brightbluelightinthemorning(whenthe sunisbrightandtheskyisblue).Bywayof explanation,morningdaylighthasahigher contentoflowerwavelength(cyan)light, whichstimulatesthecells.Thedaylight alsohasahighcorrelatedcolortemperature(CCT)intherangeof 5500 5800 K foragiventime.Progressingthroughthe afternoon,thereisagradualreductionin thecolortemperatureofdaylightuntilit reachesapproximately 2700 Katsunset, wherewarmyellows/redstakeover.These lowCCTsarepredominantlybeyondthe sensitivewavelengthrangeofipRGCs.

Althoughseeminglydifferent,ipRGCstimulationandtheCCTofnaturallighthave muchincommon;spectrallightdistributionisultimatelywhatdeterminesthese twocharacteristics.AsHCLsolutionstry tomimicdaylight,atunableipRGCsolution isalogicalmarketrequirement.Lighting designerstaskedwithdeliveringHCLneed theabilitytotunecolortemperatureand spectrum-theproportionofcyanwithin thelight.

Azurecolorthatcaneffectivelysupplylightat 480nm.

Justtobeclear,notjustanybluewillsuffice.Phosphor-convertedwhiteLEDsfrequentlyuseabluepumpintherangeof 450 nmbecauseproducingLEDsatthat wavelengthmaximizeswallplugefficiency. However,researchintothenon-visualreceptorsofhumanshasrevealedthatthe peaksensitivityforipRGCsisclosertothe cyanregion,around 480 490 nm.Todeliversystem-levelefficacyat 480 490 nm, phosphor-convertedcyanrepresentsthe wayahead,particularlyifitoffersthesame

Dynasolis™,TheCircadian TunableLightSource

Itiswelldocumentedthatlighthas asignificantinfluenceonthehuman body.Forinstance,theexposureof intrinsicallyphotosensitiveretinalganglioncells(ipRGCs)tocyanlightcan suppresstheproductionofahormone calledmelatonin,whichaffectsthehumanwake/sleepcycle.Here,lighting technologymanufacturersaretapping intotheeffectofmelatoninsuppression,whichisbeneficialincommercial settingssuchasoffices,factories,and schoolsasitmakespeoplemorealert andattentive.However,asexcessive melatoninsuppressioncanbecome detrimentaltohealth,itisimportant tolimittheexposuretocyanlightaccordingtothenaturalrhythmofthe humanbody.Fortunately,thelatest LEDtechnologycanhelplightingsystemdesignersdeliverthisfinebalance withabsoluteprecision.

ImproveAlertness,Focusand ComfortwithBiologicallyEffective Light

MennoSCHAKEL,TechnicalMarketingEngineer,Nichia

Todaylightingandlightingcontrolareincreasinglybecomingcoreelementsof IoTprojectswithinallkindsofbuildings, includingfactoriesandwarehouses,hospitalsandhealthcarefacilities,ofﬁcesand showrooms,andschoolsanduniversities. Usinghuman-centriclighting(HCL)toraise alertnessintheseenvironmentscanprolongconcentrationlevelsanddriveupproductivity.Ofcourse,someenvironments, suchashospitality,requiretheopposite ofalertness,wheretheaimistoencouragerelaxationandrest.Again,artiﬁciallight cancreatetherightmoodtostimulatethis sense.

Untilnow,attemptsatdeliveringahighefﬁcacyproducthavefallenshort.Tocreateatunablesource,currentsolutions usemelanopic-enhancedLEDsandconventionalLEDstogether.Theissueisthat melanopic-enhancedLEDsstillemitlight outsidethemelanopic-sensitivewavelengthrangeandconventionalLEDsemit lightinsidethemelanopic-sensitivewavelengthrange.Itisthereforenotpossibleto controlthemelanopiclightoutputpartof thesolutionindependentlyusingonlythe melanopic-enhancedLED.

Essentially,anipRGCColorTemperature Tunable(CTT)lightsourcehastwofunctionswithregardtocircadianlightingdesign:highmelanopiclightoutputinthe morning;andlowmelanopicoutputwhenit isnotrequired(intheeveningorinenvironmentsthatseekrelaxation).Byproviding aclearseparationofthisdualfunctionality, itbecomespossibletodesignacircadian tunablelightsourceofferingacombination ofenergizingblueandpeaceful,calming, warmwhite,asprovidedbytheDynasolis LEDlightingsolutionfromNichia [1]

Comparisonofthemelanopicratiobetweenaconventional6500KandAzure.

[1] https://led-ld.nichia.co.jp/en/product/index.html

[2] https://led-ld.nichia.co.jp/en/product/lighting_dynas olis.html

AsaTechnicalMarketingEngineerfor Nichia,Mennofocusesoncustomer’stechnicalrequirements,bridgingthegapbetweenthecustomerandNichia’sproduct researchanddevelopment.Mennoworked asanopticalmeasurementspecialistat PhilipsLightingandaBritishmeasurement laboratoryearlierinhiscareer.Heisalso amemberofseveralCIEDivisiontechnical committees.

TheFraunhoferInstituteforBuildingPhysics IBPrecentlyperformedacomparativeanalysisbetweenDynasolis [2] andstandard LEDs,attemptingtoassessthecognitive andpsychologicaleffectsofdifferentlight colortemperaturesandspectraon35volunteers.Theseeffectsincludedalertness, attention,andrelaxation.

PuttotheTest

Withthesethoughtsinmind,theoptimal solutionderivesfromcombiningtwoseparateLEDspectra:acyanLEDwithan ipRGCsensitivity-optimizedspectrumfor highmelanopicoutput(withoutemission intherestofthespectrum);andanLED withverylittletonolightinthemelanopicsensitivewavelengthrange(suchasa 2700 KLED,CRI80orevenCRI90).

TheresultsclearlyshowedtheadvantagesoftheDynasolissolution,whichprovidedequalorbetterresultsinthedifferent phasesofhumanlightingrequirements thanavarietyofstandardLEDsthanksto itscolortemperatureandspectrumtuningcapabilities.Inparticular,theattention testsrevealedsigniﬁcantimprovementsin thereactiontimesofvolunteers,supported bygoodperformancewithregardtorelax-

Traditionally,multipleLEDsofdifferentcolor temperaturesareinstalledtomeetdifferentHCLneeds.However,withDynasolis userscanbeneﬁtfromanimprovedand simpliﬁedlightinginstallationforworking environmentsthatfollowstheprincipleof HCLtoboostalertness,concentration,and comfort.

m.schakel@nichia.eu

forwardvoltageandZ-heightdimensionof thewarmwhiteLEDforfocallengthmatchinganduniformmixing.

Asaresult,designerscantodaytakeadvantageoftruedynamiclightingwithboth colorandspectraltuning,whilemaintaining highcolorrenderingandhighefﬁciency. Thebeneﬁtsareahighmelanopicratioat coolerCCTs(evenhigherthandaylight), andalowmelanopicratioatwarmerCCTs.

ation,thusdemonstratingitsabilitytomeet thefullplethoraofapplications.

References

DynasoliswillbepresentedatNichia’s boothattheLight+Buildingexhibition (Hall8,StandD60)on2-6October2022 inFrankfurt,Germany. ■

AUTHOR:MennoSCHAKEL

Insummary,mostcommerciallyavailable HCLsystemsworkprimarilybyadjusting CCT.WhileasolutionsuchasDynasolisaddressescolortuning,italsodelivers efﬁcacy,colorqualityand,mostimportantly,increasedmelanopsinstimulation, thelightthatexplicitlytargetsmelanopsincontainingneuronsintheretinaoftheeye. Theseneurons(ipRGCs)areconnectedto apartofthebrainthatregulatesthecircadiancycle,alongwithassociatedreﬂexive neuronalandhormonalresponsestolight.

SILASTIC™ MS-5002MoldableSilicone fromDow,anopticalmoldablesiliconeintroducedtothemarketintheearly2010’s, enablesadvancedAdaptive-Driving-Beam (ADB)headlamplightingsystemsinacontinuouslybroadeningselectionofcarsof allclassessince2014 [2,3].Theuseof ADBheadlamps–alreadyembracedinEuropeandAsia,helpsreducethenumberof roadwaycollisionsandincreasesautomotivesafety [4,5]

Adaptive-Driving-BeamHeadlights:

1,FrançoisDEBUYL2,email,HannesRIEGER3 ,

TheuseofAdaptive-Driving-Beam (ADB)headlampsinEuropeandAsia, togetherwiththerecentannouncementbytheU.S.DepartmentofTransportation’sNationalHighwayTraffic SafetyAdministration(NHTSA)toallow ADBonnewvehicles,willcontributeto reducingthenumberofroadwaycollisionsandanincreaseinautomotive safetyforeveryone.InjectionmoldingtechnologyforopticallytransparentLiquid-Silicone-Rubber(LSR),the properselectionofmaterial,molding parametersandautomationdesignare strategicelementstosuccessfuland efficientindustrialproductionofsiliconeprimaryopticsusedinADBheadlights.ToenableADBsiliconelens productionforheadlampmanufacturers,acrossvehiclesegmentation, DowandELMEThavejoinedefforts. Thiscollaborationaimedtovalidate thenewopticalSILASTIC™ MS-5002 MoldableSiliconefromDowusingELMET’sworldclassinjectionmolding equipment,withthecommonobjective tomanufacturecomplexopticalLSR parts,ultimatelyleadingtomoreefficientlightextractionfromtheLEDand projectionbytheheadlampsonthe road.

Moldfouling consistsofanaccumulationof nanotomicrolayersofsiliconebuilding-up ontothehighlypolishedopticalsurfacesof thesteelmoldinsert.Thisfoulingbuild-up causesdeteriorationoftheopticalsurface qualityofthelightguidesasthenumberof injectionmoldingcyclesincreases.Prior workinternaltoDowusing12-lightguide opticshaveshownalightintensitydecay

DowandELMEThavepursuedacollaborativejourneyinthedesignofaturnkey solution.ConﬁrmingthatSILASTIC™ MS5002fromDowandELMETSMARTmix TOP7000ProLSRdosingtechnology contributetoastep-changeininnovation forinjectionmoldingofsiliconelightguide lensesusedinautomotivelighting.Provingthatcombinedtechnicalexpertisein siliconechemistry,liquidinjectionmolding processingandopticsengineeringbring valueacrossthevaluechainofautomotive LEDheadlamps.

lightguidematrixmoldingtool.Aswellas adedicatedlight-engineandphotometry characterizationsetupdevelopedtocorrelatethelightintensityfromeveryindividual lightguidetothedegreeof moldfouling building-upontheinsidesurfacesofthe moldinserts,cycleaftercycle [7,8]

TheprincipleofADBheadlightswithsiliconeprimaryopticsispredominantlyused inthemarkettoimprovesystemefﬁciency. Thetechnologyisbasedondynamicand addressablecontrolofmultipleLEDlight sources.EachLEDisalignedtoasingle lightguideofamultiple-lightguidesilicone primaryopticthatprojectsthelightbeams ontheroadthroughafrontsecondaryopticinthelightengine(Figure 1) [6].ADB headlighttechnologyenableslong-range visibilitywithoutcausingglare,discomfort anddistraction,improvingsafedrivingat night.

ThetwoopticalLSRscomparedinthis injectionmoldingstudywereSILASTIC™ MS-1002andMS-5002MoldableSilicones.WhileMS-1002isalreadyqualified atamajorityofTier1headlampmanufacturersforOEMs,MS-5002hasbeen developedtoaddressspecificchallengesin productivityencounteredbyinjectionmoldersinagrowingmarket [9].Thelaunch ofMS-5002isalignedtoDow’sroadmap ofcontinuousinnovationofopticalgrade siliconematerialsinthefieldofautomotive LEDlightingapplications [7,8]

ACollaborativeApproachto EfﬁcientManufacturingofComplex ShapesOpticalLSRParts

3 HeadofR&DwithELMETElastomere Produktions-undDienstleistungs-GmbH, Tulpenstraße21,A-4064Oftering.

email francois.debuyl@dow.com

4 TS&DScientistintheMobility&TransportationdepartmentwithDowSilicones Corporation,2200W.SalzburgRd,MI48686Midland.

Introduction

MartijnBEUKEMA JakeSTEINBRECHER

1,2,5 TechnicalService&Development (TS&D)ScientistsintheMobility&TransportationdepartmentwithDowSilicones Belgium,IndustrialZoneC,B-7180Seneffe.

Toexpandproductofferingsandimprove theproductivityofADBsiliconeopticdesigns,SILASTIC™ MS-5002MoldableOpticalSiliconeisnowofferedasDow’snew benchmarkstandardofopticalLiquidSilicone-Rubber(LSR).SpeciﬁcallydesignedfortheADBmarket.MS-5002 providesauniquesetofimprovedand optimizedcurekinetics,mechanical,and opticalproperties.Enablingopticdesigns requiredforADBconceptstobereliably moldedanddemolded,offeringrobust moldingprocesswindowsforlargevolume,fullyautomatedmassproduction. Initialconﬁrmationofthisimprovementwas completedusingaDow,in-house,12-

MoldableOpticalSilicone

Whenaddingtheneedstoensureenhancedscratchresistance,bestingress protection(IP)andimpactprotection(IK) ratings,andoutstandingstabilityagainst sunlight-UVradiationandoutdoorweatheringexposures [13,14],opticalsiliconematerialshavebeenprogressivelyadoptedin keyLEDlightingapplications,e.g.,professionaloutdoorandautomotiveheadlights forinstance [6,12,15,16].

BothMS-1002andMS-5002willcontinue tobeusedtodesignandmanufacture siliconeoptics.

SILASTIC™ SILASTIC™ Property MS-5002 MS-1002 ViscosityPartA (mPa s) 62,800 39,900 ViscosityPartB (mPa·s) 14,220 17,900 MixedViscosity (mPa s) 1:1@initial 23,600 26,250 MixedViscosity (mPa s) 1:1@48h 30,000 65,000 Hardness (shoreA) 71 74 Tensilestrength (MPa) 11.1 11.2 Elongationatbreak (%) 96 80 Tearstrength (N/mm) 22.6 29.7

of10%,duetofouling,thatoccursafter ≈ 1,800-2,500shotswithMS-1002versus ≈ 7,000-10,000shotsforMS-5002.This correspondstoa ≈ 4to5timesproductivityimprovementwithMS-5002 [7,8,10]

Table1: ComparisonofMS-1002andMS-5002MoldableSilicones.ViscosityofpartA,partB,andpart [A+B]mixedwith1:1ratioandafter48hstoredinambientlabconditions.Tensilestrengthsandelongation atbreak(ASTMD412),tearstrengths(ASTMD624dieC),andhardness(ASTMD2240)afterpost-curingat 150°C.

Theunderlyingmechanismbywhichmold foulingcauseslightlossfromindividual lightguidesofthelensisillustratedin Figure 2.Astheopticalsurfaceofthe lightguidedeterioratesduetofoulingdeposits,theinternalreﬂectionconditionis disruptedandlightiscoupledoutofthe lightguideresultinginanintensitydropof thelightemergingfromtheendofthelightguide,andintheend,areductionofthe amountoflightinfrontofthecarilluminatingtheroad.

TheuseofopticalgradeLSRfordesigningandmanufacturingofopticalpartsin LEDlightingfixturesandmodulesisnow wellestablishedformorethan10years [11,12].Thebenefitsofopticalsilicone versusothertraditionalopticalmaterials usedinphotonicsapplications(e.g.,epoxy, acrylics,polycarbonate,glass,andquartz) arenumerous.Suchas:photo-thermal stability [13],highluminoustransmittance, lowchromaticdispersion(Abbenumber ≈ 52),stabilityagainstsunlightandUVradiation,easeofprocessingwithlowpressure liquidinjectionmolding,excellentsurface featurereplicationandeasilymoldedinto complexopticalshapes-includingparts withnegativedraftangles.Whenmultiple stressfactorsapplyforagivenLEDlighting application,thenthechoiceofsiliconefor designingtheopticalcomponentmakes sense.WithtrendsinLEDlightingfixtures designsevolvingtohigherpowerLED’s andminiaturization,thefollowingcharacteristicsareenhanced: (i)increasingofopticalpitchdensity, (ii)reductionofbacklightlosses,and (iii)morehomogeneouslightbeamsonthe road.

Figure1: ADBheadlightprincipleashistoricallydesignedbyDaimlerAG[2,3].Fromreference[6],with permissionofHella.

TeamDowinvestedinanin-depthoptical characterizationofMS-5002togenerateopticaldatasetsforuseinsimulation designsoftwaretopredictphotometrydistribution.Thefullopticaldatasetincludes thespectralrefractiveindex(RI)atroom andelevatedtemperatures,andthespectraltransmittanceandattenuationofthe curedmaterial.Theopticalpropertiesof MS-5002areverysimilartoMS-1002, whichallowthematerialstobeusedinterchangeablywithinthesameopticaldesign. Long-termagingreliabilityisanobviousrequirementinautomotiveapplications.The photo-thermalstabilityofthesetwosilicone materialsusedinADBheadlightengines hasbeentestedupto6,000hoursandbeyondunderconstantheatexposureupto 150 ◦Casillustratedin Figure 3

Figure4: CurekineticsofSILASTIC™MS-1002andMS-5002MoldableSiliconesat140°Cand170°C. MDRmeasurementsmadeonAlfaTechnologiesMovingDieRheometerW/S2KPremiermodelaccording toASTMD5289.

ThechemicalcompatibilitybetweenMS1002andMS-5002enablefastandefficientmaterialconversionwithmaterial scraplimitedtoaflushingstepwithnomachineryorequipmentdisassemblyneeded forcleaning.Bothformulationsshowsimilarviscosityprofiles(Table 1)andguaranteearobustpot-lifeof48hoursminimum, enablingeaseofproductionandminimal interruptionsforequipment’smaintenance.

Thissigniﬁcantchangeofcurerateisthe outcomeofMS-5002materialformulation

ThechemicalformulationofMS-5002,for improvedinjectionmoldingfabricationof ADBsiliconelenses,setstherheology, cureandmechanicalpropertiesinadifferentmaterialperformancespace.The propertiesofpost-curedMS-5002are howeververysimilartoMS-1002(Table 1). WithmaindifferencesbetweenMS-5002 andMS-1002being,atthetimeofsilicone lensdemoldingatmoldinsert’stemperature,Young’smodulus,elongationatbreak, tensileandtearstrengthvalues.Thispotentiallyleadstochallengesinverycomplex ADBopticdesignsduetohighdemolding stressloadings.Optimizationofundercuts, overﬂows,andrunnerpullers,dependon whetherpartsaremadeofMS-1002or MS-5002,andrequiremoldingtooldesign attention,withaspecialfocusonhighly sophisticatedcoldrunnerdecks,andadvancedmoldingexpertise.

ThekeyinnovationenabledbyMS-5002 isillustratedbythecurerateproﬁleplots in Figure 4.BothMS-1002andMS-5002 wererespectivelytestedat 140 ◦Cand 170 ◦C.Curekineticisdeterminedbythe temperatureofthemold-ortheMoving DieRheometer(MDR).From Figure 4,we canclearlyseethebeneﬁtsofMS-5002 versusMS-1002intermsofrateofcuring duringmaterialcureinthemold.

Figure3: Totalvisiblelighttransmission(L*)accordingtoASTMD1003ofSILASTIC™MS-5002and MS-1002MoldableSiliconeuponconstantheataging(150°C)measuredonsamplesof3mmthickness.

Figure2: Effectofmoldfoulingisreplicatedontheopticalpartcausingdisruptionofinternalreﬂection conditionsandsubsequentlossoflightfromthelightguide(bottomillustrationandpicture)[7,8,10].

AUTOMOTIVE ADAPTIVE-DRIVING-BEAMHEADLIGHTS

Issue93/Sept-Oct/2022

Thevirtualrepresentationofthelow/highbeamcombinedprimaryADBlensillustratedin Figure 5 showsthe16-lightguide functionintworowsofeightandthethick opticaloutcouplingsection.Itillustratesthe keydesignvariablestotakeintoconsiderationforoptimizingdesignandproduction set-up.InrespectofOEMcustomers’conﬁdentiality,this16-lightguidedesigndoes notcorrespondtoanyreallensdesignon themarket.

However,thereductionofthenumberof pixelsinADBheadlightsystemsisaligned torecentindustrytrendsinautomotive lighting.Whichcontributestoreducingthe manufacturingcostofLEDheadlampmodulesandexpandingADBheadlighttechnologyusingsiliconelightguideprimaryoptics lensesacrossallcarmodels,fromB-toEsegment.Therefore,offeringasafernighttimedrivingexperiencetoallend-users [4,9].Atareasonablecost,lightguidede-

LiquidInjectionMoldingand ELMETMoldTechnology

development.Overall,curingofLSRis achievedusingvinylend-blockedsiloxane polymersandresins,reactingthemwith Si-Hgroupscarriedbyfunctionalsiloxane oligomers [17].Thisaddition,orhydrosilylation,reactionoccursmainlyontheterminalcarbon(β–addition)andiscatalyzed byPtorRhmetalcomplexes,preferably organometalliccompoundstoenhance theircompatibilitywiththemedium,such as,Karstedtcatalyst [18].TheartofLSR formulationconsistsinoptimizingPtcatalystandinhibitorconcentrations,aswellas thestructureoftheSiHsiloxanecrosslinker oligomerforcontrollingtherateofcuringas functionoftemperature [19]

signswitheitheronerowof17segments, tworowsof19segmentsorthreerows of20segments,arealreadyperforming verysimilartoamulti-thousandsofpixels system [20,21].ApresenttrendinADB headlights,combininglow/highbeams istodesignsiliconelensesfrom10-upto 24-lightguide.

Toproducelensesasshownin Figure 5 withMS-5002,themoldingset-uputilizes thecurrenttechnologicalﬂagshipinLSR dosingtechnology–ELMETSMARTmix TOP7000Pro(Figure 6) [22].Thisnew versionrepresentsthethirdgenerationof dosingsystemsusedforSILASTIC™ MoldableSiliconematerialssince2012,when DowandELMETstartedtocollaborateon thequaliﬁcationofdosingsystemforopticalLSR.Intermsoffunctionality,process reliabilityanduserconveniencethedosing systemshowstechnicalfeasibilityindosingandprocessingliquidsiliconerubber. Especiallyforprocessinghighperformance LSR-types,stableandprecisemixingra-

tiosaremandatorytoensuremaximum processstability.Duetothevolumetricallymeasuredandbalancedmaterialflow, constantmixingratiocanbeguaranteed easily,notonlyfortheSMARTmixTOP 7000Pro,butalsoforthepreviousgenerationsTOP5000PandTOP3000Sdespitehighdifferencesofviscositybetween partsAandB.LowviscosityofMS-5002, withrespectively 62800 mPasforpartA and 14220 mPasforpartB,requiressuch aprecisecontrolofthe1:1mixingratio, withamaximumtolerancefordeviation of1%.Mixingefficiencyisensuredbya 30-elementstaticmixersplitin3pieces assembledinseriesafterthemixingblock. Inadditiontoexcellentmixing,ELMET’s dosingsystemsarewellknownforensuringalmostwaste-freeseriesproduction. Toincreasecostefficiencyandresource savings,theSMARTmixTOP7000Pro enablesrawmaterialutilizationofupto 99.6%,makingthesystemevenmoreeconomicthantheearliersystems.

Figure6: ELMETSMARTmixTOP7000ProandSMARTshotE[22].

Figure5: Low/Highbeamcombined16-lightguideADBlensdesign.Notethedesignisaonesinglepiece opticandthecolorcodeforthelightguidearea(blue)versustheoutcouplinglensarea(green)andthe non-opticalareas(red)areonlyforillustrationpurposes.EoAT=EndofArmTool.

∼∼∼ OMe2Si-CH=CH2+H-Si≡−→ ∼∼∼ OMe2Si-CH2-CH2-Si≡ (1)

where ≡ representstheremainingvalences ofthesiliconatom.

TheELMETteamhaveengineeredamold tooltoproduceADBmultiplelightguide siliconelenseswithcombinedlowbeam andhighbeamfunctionsasillustratedin Figure 5.Thislensrequiresaveryspeciﬁc designwitha 12 mmthickcross-section abovethelightguidesinthelightoutcouplingarea.Themaximumcross-section withthelightguideincluded,reaches 24 5 mminitscenter,leadingtochallengingcycletimesformassproduction byliquidinjectionmolding.Thevolume ofthepartis ≈ 35 cm3,correspondingto aweightof ≈ 37 5 g–giventhespeciﬁc gravityof 1.07 g/ccoftheopticalLSR.

[Pt]/[inhibitor]

Thedesignofthesiliconelens,asillustratedin Figure 5,withathickcrosssectionabovethe16-lightguidesection, directlyimpactsthecycletime;compared tofirstgenerationADBlensesthatwere flatterandthinner.Toachievemaximum productionthroughputandtobenefitfrom thecureprofileefficiencyofbothMS-1002 andMS-5002,themoldrequiredspecific engineeringonthethermaltransferside. ELMET’smoldtoolwasdesignedtoensure curingofbothMS-1002andMS-5002can takeplaceinthewidestpossibleprocess window,withmoldmechanicsoperating inarangeoftemperaturefrom 135 ◦Cto 180 ◦Candofferingtherequiredrobustnessfordemoldingthelensandoverflows. Themoldtemperature,besidesitsdirect

ADAPTIVE-DRIVING-BEAMHEADLIGHTS 48

Thepre-seriesmoldusedwasdesigned withoneuniquecavityandmanuallens demolding,andinstalledonanENGELInjectionMoldingMachine–Victory330/120 Tech.

Figure7: DeﬁnitionofthecuretimeforbothMS-1002andMS-5002,acrossthecuretemperaturerange andaccordingtotheinjectionvelocityprocesswindow.Orangecolorindicatesuncuredmaterial.

MechanismofCure

ManufacturingofthedevelopmentalADB primarysiliconeoptictookplaceatELMET. Thepre-series1-cavitymoldusesvalve gatecoldrunnertechnologyofELMET’s SMARTshotseriesforperfectcontrolof cavityfillingwithoutanysprues.ELMET colddecksareperfectlybalancedand homogenouslycooledtoensurecorrect viscosityforoptimumflowandprocess stabilitywhenproducingsiliconeADBopticsofthehighestquality.Dependingon customers’requirements,needlemovementcaneitherbedrivenpneumatically (SMARTshotP)orelectrically(SMARTshot E)withoutmakingcompromisesinprecise positioningandconstantflowrates.Dueto theverylowviscosityofopticalgradeLSR andthecomplexshapesofADBsilicone lenses,moldtoolingdesignandfabrication canbeverychallenging.

Inthemostcommon 130 160 ◦Ctemperaturerangeforproductionofautomotive ADBsiliconeprimarylenses,bothMS1002andMS-5002offeracuretimereductionof ≈ 10 sec/10 ◦Cofmoldtemperaturestepincrease.Thecuretemperature beingthepredominantfactortothehydrosylilationreaction.MS-5002offersthe beneﬁtsofitsuniquecurekineticsproﬁle toreachanadditionalaveragedgainof ≈ 10%ofcuretimereductionagainstMS1002(atleastatlowinjectionvelocity).

ELMETaddressedsuchchallengeswith innovativehigh-precisionmoldfabrication technology.Themoldinsertsweremachinedandpolishedoutofspeciﬁcsteel alloyandwithappropriatethermaltreatment,allowingforperfecttranscriptionof themoldsurfacetothesiliconeelastomer surfaceduringinjectionmoldingandcuring oftheparts,fulﬁllingopticalindustrystandardrequirementsforboth,thelightguide andtheoutcouplingsectionsofthelens.

AUTOMOTIVE

ForbothMS-1002andMS-5002materials,thecuretimewasdeterminedby consecutivecuretimeincreases,in5secondsincrements,toachievecomplete solidiﬁcationofthethickestcross-section inthelens.Avisualdeterminationofthe curetimewasachievedbycuttingthesiliconelensesimmediatelyaftermanualdemolding,intheappropriatecross-section (Figure 7).

ditiontested,takingintoconsiderationlocal cooldownatthesurfaceoftheinserts, createdbytheactionofthecoldsilicone ﬂowfromcycletocycle.Thismethodis repeatedacrossthetemperaturerange recommendedbyDow,andataselection ofinjectionvelocitiesbetween 5 cm3/s and 110 cm3/s.Duetotimeconstraints,a completeDOEcouldn’tbeperformedfor bothmaterialsandsomeconditionscombinationswereskipped.

InﬂuenceofMold Temperature

Above160°C,andforthisspeciﬁclensdesign,thepredominantfactorlimitingthe curingreaction,isassociatedtothelow thermalconductivityofthematerials, ≈ 0.2 W/mK [13].Theadvantageouscure kineticproﬁleofMS-5002,atthehighcure temperatureof 180 ◦C,dropsby 3 4 % versusMS-1002,dependingontheselectedinjectionvelocity.

Thecuretimeisdeterminedasthenecessarytimetoreachfullcureofthebulk ofthepart.Itappearsveryreproducible withavariationof+/-2secassoonasthe moldisatthermalequilibriumformolding.Thisthermalequilibriumconsidersa homogeneousheatdistributionwithinthe hotplatesandmoldinserts.Themixed partsAandBoftheLSRisinjectedliquidandcold,regulatedto 20 ◦Ctomaintainaconstantviscosityduringinjection, andisresponsibleforthermalanisotropy whenﬁllingthemoldinsertcavity,cycle aftercycle.Multiplemoldingcyclesare thereforemandatoryforeachthermalcon-

Figure8: CuretimeinthemoldasfunctionofthemoldtemperatureforMS-1002andMS-5002,injectedat variousvelocities.

influenceonlensshrinkage,wasadjusted toreachthemostefficientcycletimewith optimallensopticalquality,withoutflow linesandothersurfacedefects–asillustratedin Figure 8 -forMS-1002and MS-5002intherangeofvelocitiesfrom 20 110 cm3/s.Thisfigurecorrelatesthe timeneededtocurethematerialinthe thickestcross-section(Figure 7)withthe temperatureofthetool,fortwodifferent injectionvelocities.

BasedonELMET’sexpertise,theneedfor averywideinjectionvelocitieswindowis criticalforthemassproductionofsuch siliconelenses.Themoldandcoldrunnervalvegatetechnologyweredeveloped toallowﬂowproﬁlesfrom 5 110 cm3/s. Liketheadjustmentofmoldtemperature,

Conclusions

theinjectionvelocitywasincreasedtoits optimum.Thisvelocityisthethirdkeycontributortothecycletimereduction,after selectingtheappropriateSILASTIC™ MoldableSiliconematerialandthetemperature ofthemoldatwhichitwillbecured.With theobjectiveofreachingthemostefﬁcient productionthroughputandthesubsequentbeneﬁtsonthecostofmolding,MS5002wasselectedoverMS-1002,given

itsenhancedcurekineticsproﬁle.ThemechanicalpropertiesofMS-5002makeit fullycompatiblewiththemoderatedegree ofcomplexityofthislensdesign.While screeningtherelationshipbetweeninjectionvelocityandthemeasuredmaterial pressurerequiredbythemachinetoreach theﬂow(Figure 9),theexpectedlinear correlationisobservedacrossalmostthe entirevelocityrange.Asmallpressuredrop createdbytemperatureelevation,while marginal,isneverthelessexplainedbymaterialviscositydecreasing,eventhoughthe materialismeteredataconstanttemperatureof 20 ◦Cinthescrew/barrelofthemachine.Itsinjectionthroughthegatepoint, atmoldtemperatureinthe 130 180 ◦C range,slightlyelevatesitstemperature leadingtothe ≈ 8 barpressuredropper 10 ◦Cmoldtemperatureincrease.Thiseffectcanbeconsideredasnegligeablefor LSR.

Theeffectivecollaborativeapproachof DowandELMEThaveproventosigniﬁcantlyadvancetheunderstandingofhow opticalsiliconeelastomerformulationsand liquidinjectionmoldingprocessingareintimatelyrelated.FromDow’sside,both SILASTIC™ MS-1002andMS-5002MoldableSiliconearecomplementaryoptical LSRthatarenowofferedtothemarket. Bothmaterialsarecommerciallyavailableformassproductionofsiliconeop-

InﬂuenceofInjection Velocity

Inadditiontothecuretimereduction,directlyimpactedbythematerialformulation anditsassociatedcurekineticsprofile,the influenceoftheinjectionvelocityisillustratedin Figure 10 forMS-5002.Being inalaminarflowregime,thankstosmall pipedimensionsinthemoldingtool,the temperatureincreasesintothematerialresultsfromfriction,whichdependsonthe velocityprofileinsidethepipes.Therefore, theself-elevationofmaterialtemperature, whichcontributestoacceleratecurekinetics,istheconsequenceofshearrateprofile appliedontheLSRduringinjection.This laterisinfluencedbythespecificmolding tooldesignandSMARTshotEcoldrunner engineeredgeometry.Liketheeffectofthe curetemperature,theimpactoftheinjectionvelocitycanbeaveragedatavalue of5%reductionper 20 cm3/svelocityincrease.Exploringthemoldingprocess windowboundariesbycombiningcure temperatureandmaterialvelocity,plus thenewMS-5002material,fortheparticulardesignof Figure 5,demonstrateda totalgainupto50%incuretimereduction,from[130 ◦C@ 5 cm3/s]to[180 ◦C@ 110 cm3/s].

Figure9: PressureofinjectionofMS-5002neededforreachingagiveninjectionvelocity. Figure10: TimecuringinthemoldasfunctionofvelocitiesofinjectionofMS-5002inmoldcavitysetat varioustemperatures.

[13] F.deBuylandS.Yoshida,“ReliabilityofOrganic CompoundsinMicroelectronicsandOptoelectronics –chapter1:DegradationMechanismsofSilicones”, W.D.vanDrielandM.YazdanMehreditors,Spinger publisher,ISBN978-3-030-81575-2, https://doi.org/ 10.1007/978-3-030-81576-9 (2022).

WhileSILASTIC™ MS-1002MoldableSiliconeisqualiﬁedasaglobalindustrystandardinlightingapplicationssincetheearly 2010’sandhasproveditsperformance since2014inADBheadlampssystems, nextgeneration’sSILASTIC™ MS-5002 fromDowsetsanewstandardofperformance.Themechanicalproperties,at demoldingandafterpost-curingstages, enabledesignfreedomfornextgenerationofADBsiliconelensescombining variousmultiple-lightguideshapesandvariablepartthicknesses.Theopticalperformanceinlong-termexposuretohighheat (upto 150 ◦C)andhighphotondensity meetAutomotiveStandardsrequirements worldwideandprovidestableandhigh lighttransmittanceoverthelifetimeofADB headlamps.Therobustshelf-lifeandstable pot-life,inadditiontotheoptimizedrheologyandcurerateofSILASTIC™ MS-5002 MoldableSilicone,contributetoaneaseof moldabilityandmachinerymaintenance, andofferaﬂexibleproductionschedule fromsmall,withfrequentinterruptionsto full-scale24/7productionschedules. ■

[10] J.Steinbrecher,“InnovationinLiquidSilicone Rubber:Usingsoundmaterialsciencetosolveperformanceandmanufacturingchallenges”,LSR2021 (14Sept.)Chicago.

[18]

[21] P.Ferbas,J.Martoch,S.Büttgen,H.Groner (VarrocLightingSystem),“OptiADBandStudyon LowNumberofSegments”IQPC20thIntelligent AutomotiveLightingconference,Cologne,February 17-20(2020).

[3] M.Maier,DAIMLERAG“MULTIBEAMLEDLights UptheNight.TheFutureofIlluminationTechnology atMercedes-Benz”,IQPC15thIntelligentAutomotive Lightingconference,Dusseldorf,January28(2015).

[22] ElmetSMARTmixTOP7000ProandSMARTshot E,accessibleon https://www.elmet.com/EN/downloa ds

[4] AmericanAutomobileAssociation(AAA),2019 https://www.aaa.com/AAA/common/AAR/files/Resea rchReportEuroSpecvsUSHeadlamps.pdf

[20] D.Hynar(Varroc),“OverviewofcurrentADBsolutionslowtohighcost”,IQPC19thIntelligentAutomotiveLightingconference,Mainz,February20-22 (2019).

tics.Theirrespectivecompositionmakes themperfectlyinterchangeablefromdosingtoinjectionunit.SILASTIC™ MS-5002, however,wasrecentlydesignedandformulatedtoenhancetheproductivityof ADBsiliconelensesforfabricators.With dualgains,(i)ofreducing/suppressing moldfoulingforseveralthousandsofinjectionmoldingcycles–dependingon complexityofthelensdesignandinjection moldingparameters(temperature,curingtime),and(ii)inreducingcuringtime andthereforeproductionthroughput.Delivering4-5ximprovementinthenumber ofinjectionmoldingcyclesbetweenmold cleaningwhilemaintaininggoodoptical quality,SILASTIC™ MS-5002contributes directlytoincreasemassproductionefﬁciencybyliquidinjectionmolding.ELMET’s SMARTmixTOP7000ProdosingsystemandSMARTshotEinjectionmolding tooltechnologyhavebeenproventoofferanoptimalturnkeyinjectionmolding setupwhencoupledwithanENGELVictory330/120Techinjectionmoldingpress.

SteinJ,LewisLN,GaoY,ScottRA.,“InSituDeterminationoftheActiveCatalystinHydrosilylation ReactionsUsingHighlyReactivePt(0)CatalystPrecursors”,J.Am.Chem.Soc.,vol.121,pp3693-3703 (1999)

[19] P.Beyer,N.Gerard,H.P.Wolf,“Lowtemperature cureofliquidsiliconerubber”,RFPInternational,vol. 14,issue3,pp.168-172(2019).

MartijnBEUKEMAmabeukema@dow.com, FrançoisDEBUYLfrancois.debuyl@dow.com, HannesRIEGERh.rieger@elmet.com,Jake STEINBRECHERjacob.steinbrecher@dow.com, KevinV.TIGGELENkevin.vantiggelen@dow.com. (toptobottom)

[5] E.Edmonds,“It’sTimetoBringU.S.Headlight StandardsOutoftheDarkAges”,AAANewsroom, April16,2019. https://newsroom.aaa.com/2019/04/r esearch-european-headlight-technology-us-low-bea m-safety/

[2] M.Maier,J.Moisel,F.Herold,“MultibeamHeadlightsintheMercedes-BenzCLS-Class”,ATZWorld, vol.117,pp.4–9(2015). https://doi.org/10.1007/s383 11-015-0156-0

[8] M.BradfordandF.deBuyl,“Solutionsfortheevolvingautomotivelightingindustry”,IQPC21thIntelligentLightingconference,onlinewebinar,October5 (2021).

[1] SILASTIC™ MS-1002MoldableSiliconesA/Bkit, https://www.dow.com/en-us/pdp.silastic-ms-100 2-moldable-silicone-ab-kit.04093229z.html

[9] S.Klapper(IHSMarkit),“ShapingtheFutureof AutomotiveLighting:AglobalOutlook”,IQPC20th IntelligentAutomotiveLightingconference,Cologne, February17-20(2020).

[11] F.deBuyl,etal.“DowCorningMoldableSilicone LeadingInnovationinLEDLightFixtures”,Journal ofTheSocietyofSiliconChemistryJapan,No.31; pp.23-38(2014).

[15] “DowandSchréderteamupforEasternEurope’s ﬁrstLED-illuminatedsportsstadium”,DowFormN° 11-3890-01A(2019),availableon https://www.dow. com/documents/en-us/case-study/11/11-38/11-389 0-01-sports-stadium-illuminate-schreder.pdf

[16] “CarcloS1Optic’slightenginedesignedwith SILASTIC™ MS-4002MoldableSilicone”,DowForm N°11-4233-01-0821AMPM(2021),availableon https://www.dow.com/documents/en-us/case-study /11/11-42/11-4233-01-carclo-optic-engine-silasti c-ms-4002-moldable-silicone.pdf

References

[7] M.Beukema,F.deBuyl,V.Jansma,J.Steinbrecher, K.VanTiggelen,“Solutionsandconceptsforthe evolvingautomotivelightingindustry”accessibleon demandfromSILASTIC™ MS-5002MoldableSilicone (https://www.dow.com/en-us/pdp.silastic-ms-500 2-moldable-silicone.504791z.html?productCatalogF lag=1#overview).

[12] “MoldableOpticalSiliconeElastomersSpark creativityinLEDLighting”,LaserFocusWorld,pp. 41-45(October2019),publishedonlineon https: //www.laserfocusworld.com/optics/article/14040094/ moldable-optical-silicone-elastomers-spark-creativit y-in-led-lighting

[14] M.YazdanMehr,W.D.vanDriel,F.deBuyl,G.Q. Zhang,“StudyontheDegradationofOpticalSilicone ExposedtoHarshEnvironments”,Materials,vol.11, pp.1305(2018).

[17] F.O.Stark,J.R.Falender,A.P.Wright.“Silicones. ComprehensiveOrganometallicChemistry”.G. Wilkinson,F.G.A.Stone,E.W.Abeleditors.Pergamon Press.2,305-363(1982).

[6] “SILASTIC™ moldableopticalsiliconeshelppave thewaytoagroundbreakingLEDheadlampdesign fromHellaKGaAHueck&Co”,Dowcasestudyform ref11-3675-01C(2019).AvailableonlinefromHella KGaAHueck&Co.DevelopsLEDHeadlampDesign: CaseStudy(https://www.dow.com/documents/en-u s/case-study/11/11-36/11-3675-01-pave-the-way -groundbreaking-led-headlamp.pdf)

Thismediocrecompatibilityperformanceis indeedaproblem,especiallyformanylarge retroﬁttingprojects.Inresponse,rather thansolvetherootcauseproblem,LED tubemanufacturersintroducedproducts thatcarryanotherfeature,i.e.,theycan workwithdirectmains, 230 Vor 120 V. Thisentitlestheinstallertobypasstheballastandrewiretheluminairetomainsto maketheinstallationwork.Theseproducts arecalled“universal”LEDtubes,because theycanworkwithalltypesofinstallations, i.e.,ACmains,electro-magneticballasts, andelectronicballasts.(IntheUSthese typesoftubesarecalledTypeA+Btubes [6]).

1LEEDprovidesaframeworkforhealthy,efﬁcient, carbonandcost-savinggreenbuildings.LEEDcertiﬁcationisagloballyrecognizedsymbolofsustainability achievementandleadership.

HiddenChallengeandItsSolution forRetroﬁtLinearTubeLamps

Globally,fluorescentlightingcontributed closeto64%oftotallightdelivered,was 38%ofalllightingsales,andaccountedfor 45%ofelectricityconsumption [2] asof 2012andthesenumbershavenotdrasticallyreduceduntil2019.Globalfluorescent lightingsalesstillaccountfor33%asof 2020 [3].IntheUS,approximately40% [4] oftotallightingelectricitywasconsumed inthecommercialsector,forwhichlinear fluorescentremainsthepredominantlightingtechnology.There,T84ftandT124ft lampsaccountfor84%ofthetotalinventoryoflampstypesforLFLs.InEurope, closeto8billionLFLs [5] weresoldbetween1990and2013.Thelinearfluorescentlampreplacementmarketisthelast conventionaltechnologymarketleftthat needsLEDretrofitting.

LinearFluorescentLamps

Thequestionathandishowtoseamlessly andinexpensivelyLEDifytheexistinginstalledbaseofLFLluminaires.Asolutionis tosimplythrowawayworkingfluorescent luminairesandreplacethemwithnewLED luminaires.Thisisnotonlyanexpensive solution,butalsoleadstoexcessiveelectricalandmaterialwaste(e.g., ≈10 15 kg pertrofferfixturecomparedto ≈2kgor lessforlampreplacement).Themostinexpensivesolution,whichalsogenerates theleastelectricalandmaterialwaste,is aplug-and-playretrofitlinearLEDlamp technologywhichiseasytoinstallandis permittedtoworkforallapplications.Many believethereareplug-and-playLEDsolutionsthatcanimmediatelyreplacethe T12/T8/T5fluorescentlampsintheceiling. Ifthisisthecase,whyistheadoptionrate soslow?

magneticballastsaretheolder,lessefficienttechnologyandhavealwaysbeenin theprocessofbeingphasedoutinmuch oftheworld,especiallyforthepopular T8lampcategory,from2012onwards. Electronicballasts(100%exclusivelyused intheUSforT8lampsandrepresenting about1/3rd ofthetotalEUmarket [5])have progressedsteadilyoverthedecades, butthereisnotauniformtechnologyinside.Eachdifferenttechnologyimpactsthe compatibilityoftheelectronicballastwitha retrofitLEDtube.Intheworstcases,ifitis pairedwithaLEDtubeinsteadofalinear fluorescentlamp,theballastsimplyrefuses toturnon.ThevastmajorityofLEDretrofit linearlampshaveelectronicballast‘turnon’compatibilityrangingfrom 60 85 %, accordingtoverifiedstudiesperformedby Seaborough.

≈11%in2017,whileoutdoorandroadway LEDlightingwereapproaching50%that sameyear [1]

Onereasoniscompatibility.TheLED solutionmustcontendwithanexternal ‘ballast’,installedbetweenmainspower (230 V/120 V)andthe(originally,ﬂuorescent)lamp.Ballastsareoftwotypes, electromagneticandelectronic.Electro-

Compatibility

Wehavehadthemfromtheearly1960’s andfindthemstillnowintheceilingsof manyoffices,retailshops,parkinggarages, industriesandsimilarinstallations.While theworldmovestowardsavisionofbrand new,LEEDs-certified1 greenbuildingswith thelatestininternet-of-things(IOT)based lighting,therealityhauntsusonhowto confidently‘LEDify’anoldinstallationhavinglinearfluorescentlamps(LFLs).This hesitationisreflectedintheadoptionnumbers.IntheUS,forexample,LEDpenetrationofthelinearfixturemarketwasonly

This“cut-wire”approachiseasiersaid thandone.IntheEU,theCEcertification markoftheluminaireislostifthewiringis tamperedwith,andinstallerswouldprefertoavoidtheliabilityassociatedwith firehazard.IntheUS,itisatadeasieras certifyingbodiesliketheUnderwritersLaboratory(UL)allowstheelectricianmaking thechangetoself-certifyafterusingUL markedcomponentsinre-wiringtheluminaire [6].Inanyevent,apureplug-andplayretrofitsolutionwouldbepreferable foreveryone,savingconsiderabletimeand moneyininstallation,aswellasavoiding increasedriskoffirehazard.

In2023,theEU’sRoHSdirectiveban onmercurylampswillopenanenormousopportunityforincreasedLED lightingadoptionwithitsclear-cutadvantagesinenergysavingsandgreenhousegasemissionsreductionscomparedtofluorescentlighting.However,unlikemostlamps,linearfluorescenttubesarenotself-ballasted. Fortrue“plug-and-play”actiontheir replacementcounterpartsmustcontendwiththeballastalreadyintegrated intotheexistingluminaire.Toassess theprognosisforretrofittingreal-world luminaires,weconductedastudyof compatibilityoftop-tiercommercially availableLEDlineartubelampswith electronicballastsrecoveredfrom constructionprojectsinWesternEurope.Whilesometurn-onincompatibilitywasindeedobserved,ofmore concernwasthewidespreadinlamp consumedpowerdependingonwhat ballasttypewasused.Thepower spreadofthesetop-tiercommercially availableLEDlineartubelampsisso wide,astothreatenthereturn-oninvestmentandclimateprotectionexpectationsforconversiontoLEDs.In thispaperwediscussthisproblemand presentapracticalsolutionavailable forallLEDlineartubesolutionsonthe market.

Dr.MikeKRAMES(Sr.Advisor)andPieterSIX(CEO),Seaborough Research,TheNetherlands

Ofperhapsgreaterconcerniswhathappensonthehigh-powerside,sincepower drawinexcessofwhatisrequiredforthe lightingapplicationthreatenstheenergy savingsreturn-on-investmentaswellas theentitledclimateprotection(fromgreenhousegasemissionreduction)fromthe switchtoLEDlighting.Indeed,theEUregulationmentionedalreadyconsidersthis aswellandrequiresthatlampsdelivernot morethan5%oftheir“declared”power [8].(Thedeclaredvaluesarethoseprovidedbythelampmanufacturerforwhen thelampisconnectedtomains.)Thisvital issueisnotreflectedinpublishedcompatibilitylistsbymanufacturersofLEDtube lamps,whichis,accordingtous,notjustifiable.Excesspowersignificantlylowers thetruecompatibilityofconventionalLED tubeswithelectronicballasts,whichisa criticalparameterfortheadoptionofthe retrofitLEDlamptechnology.

TherootcauseofthispowerspreadisbecausetheLEDstringvoltageisdramatically differentthanforﬂuorescentlampsand thechangeinloadcausestheballastto shiftitsoperatingfrequencyinresponse. Differentballasttypesbehavedifferently tothisloadshift,andthisresultsinawide rangeofpowersbeingsuppliedbydifferent ballastswhichmustbeabsorbedbythe lamp.Inordertomitigatethisissue,we introducethenotionofa“virtual”LEDload comprisingtwostringsofLEDswhichare operatedinswitchmodeathighfrequency (> 150 kHz).Analgorithmincorporated intotheelectronicscanselectavoltage betweenthatoftheﬁrstLEDstring,and

Intermsofsystempowerdraw(ballast andlampincombination),prototypelamps utilizingthisactive-power-control(APC) showasimilaraveragepowerdrawto conventionalLEDtubelamps,butwitha dramaticallytighterrangeanddistribution. Asshownin Figure 2,alampusingthe APCtechnology(referredtobySeaboroughasUltima™)-usingthesameballasts asforthecommerciallyavailableLEDtubes ofCompanyAandCompanyB-showa standarddeviation8%comparedtoexcessivelywidestandarddeviations(21 24 %) forconventionalLEDtubeproducts.Indeed,theUltima™ systemshowsasimilar tightdistributionasforﬂuorescentlamps, butwithsigniﬁcantlylowerpowerconsumption.

cannotguaranteethetargetilluminance levelfortheapplication.Incaseswhere luxorlumenscannotmatchtheapplicationminimumrequirements,ballastorlamp combinationsgivinglowpowershouldbe deemed,infact,incompatible.ThisaspectispinpointedinrecentEUregulations whichrequireLEDlampstoproducelight levelshigherthan10%belowtheirrated outputlevels [8]

Intheend,themainaimofconvertingto LEDlightingistosaveenergycomparedto afluorescentlamp(andofcourseeliminate theenvironmentalhazardsassociatedwith mercury).T8LEDretrofitlampsaremarketedwitha50%energysavingmarketing claim.Thisclaimfromthelampmanufacturerholdstrueforinstallationswherethere isanelectromagneticballastconnected tothetube,orthetubeisconnecteddirectlytomains.However,installations havingelectronicballastsdonotguarantee50%energysavingfromretrofitLED tubesasweshallillustrate.Thisisbecause oftheunderlyingtechnologiesintheinstalledelectronicballasts,whichcanresult insignificantshiftsinpowerdrawnthrough theballast,dependingontheLEDtube productitisenergizing.Endusersand decision-makersforlightinginstallations areusuallynotawareofthisproblemand canbeunpleasantlysurprisedlaterwhen theirreturnoninvestmentaftertheretrofit LEDlampsdoesnotmatchthe50%power savingsthattheywerepromised.

Nowlet’sconsidertheproblemfromthe lampperspective.Indeed,lightoutputfor LEDproductsisgenerallylinearwithinputpower.Basedontheabove,thereis strongreasonforconcernthatlightoutput fromLEDlampsinLFLretroﬁtinstallations canvarydependingonthetypeofelectronicballast,somuchsothatinstallers

Figure 3 showsasummaryoflamppower measurements,comparingthetwoconventionaluniversalLEDlamps(CompanyA andCompanyB),andtheUltima™ (APC) lamp,forthesamevarietyofballastsas for Figure 2.Asforthesystempower measurements,thelamppowersforthe conventionaluniversalLEDtubeandballast combinationsshowwidedistributions.In

PowerSavings

Indeed,byrecoveringelectronicballasts fromconstructionprojectsthroughout WesternEuropeinrecentyears,weobtainedmorethan450electronic,nondimmableballastsfrom55differentEU wideballastmanufacturerssuitedforall threeT8lamptypesnamely1/2x58W 1500mmT8,1/2/3x36W1200mmT8and 1/2/3/4x18W590mmT8.Includedinthis setwere73electronic,non-dimmableballasttypesfrom24differentmanufacturers suitedfora1x58W1500mmﬂuorescent lamp,asshownin Figure 1.These“FieldRecovered”ballastswerethentestedby poweringupavarietyofUniversal/TypeA /TypeA+BLEDtubeproducts.Ourdata showsthat,unlikeforelectromagneticballasts,energysavingswithconventional LEDtubesisbynomeansguaranteed,and indeedcanvaryalotdependingontheballasttype.

Figure1: Paretoofmanufacturersfor“ﬁeld-recovered”electronicballastsfromlinearﬂuorescentluminaires collectedbetween2018-2020inwesternEuropeforthisstudy.

bothstringsinseries,inordertoactively controlthepowerdeliveredtothelamp.In essence,smartelectronicsauto-adaptto theinstalledballaststopresentasuitable electricalload.Detailsofthisactivepower control(APC)approachandcircuit,and anextendedstudyincludinganincreased numberofevaluatedballasts,arepublished elsewhere [7]

SystemPerformance

LampPerformance

Co.A“Compatibility List” 7 14

Acknowledgements

OnemightarguethatCompatibilityLists providedbyLEDlampmanufacturersare thewayaroundtheproblemsofballast incompatibilityandlamppower-shift.The numbersspeakforthemselves. Table 1 comparesthenumberandtypeofFieldRecoveredballaststestedbySeaborough vs.thatfromCompatibilityListsoftwo

SeaboroughbelievesthatLEDretroﬁtlamp productsshouldbecompatiblewithany ﬁxture,regardlessoftheinstalledballast type,andthattheentitledenergysavingsshouldbeguaranteed,alongwith

Figure2: Systempowers(measuredatballastinputs,for73differentfield-recoveredelectronicballasts)for lineartubelamps:a)fluorescent,b)andc)conventional“universal”LED,andd)activepowercontrol(APC), orUltima™.EachLEDlamphasatypicallightoutputofabout3000lumens.ConventionalLEDtubes showawidevariationinpowerdrawcomparedtothefluorescentandtheUltima™lamp.

LEDretrofitlampsofferthequickest,most inexpensive,andlowestenvironmentalimpactsolutiontorealizingenergysavingsby replacingLFLs.Nevertheless,marketpenetrationrunslowerthanmanyotherLED retrofitapplications.Oneofthelargestbarrierstoadoptionhasbeenpoorcompatibility,notonlyregardingbasicfunctionality, butalsotheunspokenproblemsofguaranteeingenergysavingsandlight-output uniformityinretrofitprojectsinvolvingelectronicballasts.Usingactivepowercontrol (APC)technologywhichwecallUltima™ , Seaboroughhasshownthattheseproblemscanbesolved,andthatfullretrofit solutions,withnocompromises,areavailableforthemarket,endingtheargument that“nogoodsolutions”existanddestroyinganyjustificationsforthosewhowould lobbytocontinuepropagatingmercurybasedfluorescentlampmanufacturingat theexpenseoftheglobalclimate.

Issue93/Sept-Oct/2022

Theauthorswishtothankmembersofthe ElectronicsTeamatSeaboroughResearch B.V.fortheircontributionstothiswork:S. Cetin,S.Chingaira,R.Klein,U.Ozturk,S. RoyandJ.Wongsodikromo.

Indeed,fullsolutionsarenowavailable, andtheworld,bothintermsofenergysavingsaswellasforitsclimate,willbebetter offasweunlockawaveofLEDadoption thatwillmakemercuryLinearFluorescent Lampsadistantmemory. ■

Forreal-worldretroﬁtprojects,thesituation willbeworse,notbetter.Itbecomesclear thattheCompatibilityListapproachto supplyingLEDretroﬁttubelampsisan unworkablesolution.

b. Signiﬁcantlyreducedpowerspread comparedtoconventionalLEDtubelamps, shoringuppowerloadandavoidingballast reliabilityandsafetyissues;and

FieldRecovery 24 73

a. Guaranteedenergysavings:theactual lamppowerforanyballastcanbevery closetotheproductratedpower;

c. Predictablelumenoutput,asexpected fromtheproduct,irrespectiveofthetypeof electronicballast.

HIDDENCHALLENGEANDITSSOLUTIONFORRETROFITLINEARTUBELAMPS 54

Co.B“Compatibility List” 8 25

Table1: Numberofmanufacturingbrandsand modelsforﬁeld-recoveredballasts(thisstudy) comparedtothosein“CompatibilityLists”from twoprominentsuppliersofLEDtubelamp productsforLFLreplacement.Thewidegapin coverageofthelatterwithrespecttothe real-worldsituationisstark.End-usersrarely knowtheactualmodelsofballastsinstalledat theirfacilities,makingCompatibilityLists practicallyuseless.

LAMPTECHNOLOGIES

thelumenperformance.Customersbuy alamp,anditshouldperformconform productspecsstatedonthepackaging. TheUltima™ (APC)lampdemonstrated inthispaperaimstoguaranteeentitled energysavingswhenconvertingLFLsto solid-statelightinglampsandtodeliver theexpectedreturnoninvestmentinenergybillstoend-users.Thetechnology describedhereispatented [9] andavailablethroughSeaboroughtothelighting industrybroadly,andpresentsthefollowing advantagesoverthestandardretroﬁtLED technology:

addition,severalballast/lampcombinations donotturnonatall(9of73,and8of73, forCompanyAandCompanyB,respectively).Using90%targetedpowerdrawas aproxythresholdformeetinglightingdesignrequirements,anadditional6combinationsforbothCompanyAandCompany Baredeemedlowﬂuxandnotcompatible.Onthehigh-powerside,anadditional 29and34combinations,forCompanyA andCompanyB,respectively,wouldnot meettherequirementtoconsumeless than5%abovetheirratedpowers.This leavesthenumberofremaining,compatiblelamp/ballastcombinationsatonly29 (40%)and25(34%)forCompanyAand CompanyB,respectively,outofthe73ballasttypestested.Incontrast,theUltima™ (APC)lampprototypepasseswith81%of casesmeetingthe-10%/+5%powerdistributionrequirementinthespiritoftheEU regulation.(Sincetheprototypelampdid nothavea“declared”value,itsstatistics werecalculatedwithrespecttothemedian powerconsumedwhentestedwithall73 ballasttypes).

prominentLEDtubelampmanufacturers. Inour(admittedlylimited)ﬁeld-recovery project,Seaboroughalreadyuncovered morethanthreetimesasmanybrands andmodeltypesthanarelistedinthetwo CompatibilityLists.

No. Brands No. Models

Conclusion

HIDDENCHALLENGEANDITSSOLUTIONFORRETROFITLINEARTUBELAMPSLAMPTECHNOLOGIES

[2] “ACCELERATINGTHEDEPLOYMENTOFSOLID STATELIGHTING(SSL)INEUROPE,”AAlmeida,G Zissis,MQuicheron,PBertoldi,PublicationsOfﬁceof theEuropeanUnion,EUR–ScientiﬁcandTechnical Researchseries–ISSN1831-9424(online)ISSN 1018-5593(print)

[6] LEDL040-GE-The-ABCs-of-LED-Tubes-UL-TypeWhite-Paper;availableat: https://www.bomadallas.o rg/files/White%20Papers/ABC’s%20of%20LED%20T ubes%20-%20FSG.pdf

PieterSixhasmorethan15yearsofexperienceinmarketing,businessdevelopment andsalesatbothCorporateInstitutions andStart-ups.Hehasextensivegeneral managementexperienceworkinginEurope andAsia.Heispassionateaboutmaking connectionsbetweenbusinessproblems andtechnology,ultimatelytocreatestate oftheartanduniquesolutions.PieterSix iswellversedintheworldofLED.Before joiningSeaborough,heworkedasChief CommercialOfﬁcerforEllipzSmartSolutions,aninnovativecompanyactivein theworldofLiFitechnology.PieterSix willfurthershiftthescopeandfocusof Seaboroughtowardsmarketintroductions togetherwithbusinesspartners.

p.six@seaborough.com

[3] IEA(2021),Lighting,IEA,Paris https://www.iea.org/ reports/lighting

[7] SRoyandMKrames,“ActivePowerControlof RetroﬁtLEDTubeLampsforAchievingEntitled EnergySavingsinViewoftheEUBanonMercury,”Sustainability2022,14,10062. https: //doi.org/10.3390/su141610062

[1] U.S.Dept.ofEnergy,EnergySavingsForecastof Solid-StateLightinginGeneralIlluminationApplications,December2019

MikeKrameshasmorethan25yearsof materials,device,andapplicationsexperience,withemphasisonsolid-statelighting devicesandproducts,includingadvancingtheperformanceandcolorqualityof LEDsforgeneralillumination.HeiscurrentlypresidentofArkesso,LLC,aconsultingﬁrminSiliconValley,andSr.Advisorto SeaboroughResearch.Dr.Krames’previousrolesincludeChiefTechnologyOfﬁcer ofSoraaInc.,andExecutiveVicePresidentofAdvancedLaboratoriesatPhilips Lumileds.Dr.Krameshasover90publicationsandhasbeengrantedover200 patentsworldwide.HeisaFellowMember ofbothIEEEandIES.

[8] COMMISSIONREGULATION(EU)2019/2020of1 October2019layingdownecodesignrequirements forlightsourcesandseparatecontrolgearspursuant toDirective2009/125/ECoftheEuropeanParliament andoftheCouncilandrepealingCommissionRegulations(EC)No244/2009,(EC)No245/2009and(EU) No1194/2012,12May2019.

[9] InternationalPCTPublicationNo.WO2020/084087 A1.

AUTHOR:PieterSIX

References

[4] U.S.Dept.ofEnergy,2015U.S.LightingMarket Characterization,November2017

[5] VHK,“ModelforEuropeanLightSourceAnalysis (MELISA)”Version0,preparedfortheEuropean Commission,Brussels,31January2015

Figure3: Lamppowers(measuredatballastoutputs,for73differentﬁeld-recoveredelectronicballasts)forlineartubelamps:a)andb)conventionaluniversalLED, andc)activepowercontrol(APC),orUltima™.ConventionaluniversalLEDtubesexhibitawidevariationinlamppowerdraw:manydonotturnon,andmanythat do,drawsigniﬁcantlymoreorlessthantheirratedpower.FortheUltima™,(APC)lampprototype,compatibilityisveryhighandthepowerspreadisminimized.

AUTHOR:Dr.MikeKRAMES

AWARD CATEGORIES 2022 Product DesignScientificSustainabilityAwardAwardPaperAwardAward

At the annual LpS Digital Conference (December 7, 2022), the LpS Digital Awards will be presented in four specific categories.

www.LpS-Digital.globalinfo@lps-digital.global

HIDDENCHALLENGEANDITSSOLUTIONFORRETROFITLINEARTUBELAMPSLAMPTECHNOLOGIES Issue93/Sept-Oct/2022 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design 57 LPS CONFERENCEDIGITAL2022 DECEMBER 7, 2022 2PM – 5PM CET The LpS Digital 2022 Awards ceremony will also take place during this event. Supportedinfo@lps-digital.globalwww.LpS-Digital.globalby Register Now EXPERIENCE THE FUTURE OF LIGHT

HowtoAssesstheEyeSafetyof VCSELs–Introduction

Vertical-cavitysurface-emittinglasers (VCSELs)perfectlyfulfilltherequirementsforpresentandfuture3Dsensingapplications.However,tooperate VCSEL-baseddevicesinpublic,the manufacturermustassuresafeoperationcompliantwiththeIEC608251standardornationalequivalents. AsVCSELsexhibitspecialemission characteristicsthatdifferfromother lasersources,thesafetyassessment ismorecomplexandapracticalguidelinedoesnotexist.Inthispaperwe explainthedifferencesofVCSELsas comparedto“normal”collimated, Gaussianlasers,andoutlinethemain stepsnecessaryforVCSELsafetyassessment.

Eventhoughvertical-cavitysurface-emitting lasers(VCSELs)havebeenemployedin variousindustrialapplicationsforoverthree decades,theyhaveonlyrecentlygained greatpopularityandexperiencedrapid economicgrowthsincethereleaseofApple’siPhoneXandFaceIDtechnology. Duetotheiruniquefeaturessuchasvery highconversionefﬁciency,anarrowspectrum,highbeamquality,andlowproductioncosts,VCSELdevicesareperfectly suitedfor3Dsensingapplications,e.g. usingstructuredlightortime-of-ﬂighttechnologytoscanobjectsin3D.Ontheone hand,VCSELtechnologyisabouttohave itsbreakthroughinconsumerelectronics andwillbecomeastandardpartofmobile phonesandAR/VRsystems.Ontheother hand,VCSELsaspartofLIDARsystems couldbecomeindispensablecomponents forautonomousdriving.

AsVCSELshavepropertiesdifferentfrom othertypicallasersources,thedeterminationofasuitablelaserclassiscritical: evenmoreso,asnoeasilyunderstandable guidelinefortheassessmentofVCSEL safetyhasyetbeenpublished.

TheIEC60825-1Laser SafetyStandardAppliedto VCSELS

However,likealltypesoflasers,VCSELs canpotentiallyharmthehumaneyeand skin,andmaycauseseverehealthdamage,suchasretinadestructionorskin burn.ConsumerelectronicsandLiDAR manufacturersarethereforeobligedto carryoutalasersafetyassessmentoftheir productsinconformancewiththeinternationallasersafetynormIEC60825-1or equivalentnationalsafetyregulations [1,2]

Introduction

Withourinvestigations,weaimtoﬁllthis gap.Inthiscontribution,wepresentthe resultsofourlasersafetyconsiderations basedontheinternationallasersafety

GüntherLESCHHORN,Dr.,TianyuanCAO,KarhikIYER,Dr., InstrumentSystems

normspeciallyappliedtotypicalpulsed VCSELarrays.Thisarticleprovidesthe basicsanddiscussesageneralapproach tothistopic.Afollow-uparticleisalsoto bepublished,discussingtwohands-on, step-by-stepexamplesofthelaserclass assessmentofVCSELsources.

LasersafetynormIEC60825-1istheinternationalstandardforlasersafetyassessment.Itdividesthepotentialrisks ofalaserintofourmaincategories(and subcategories)rangingfromlaserclass1 “safetouseinpublic”to4“veryharmfulto eyesandskin”.Itisintendedtocoverall kindsoflasers,andhenceisgeneralized withoutfocusingonthepeculiaritiesofcertaintypesoflasers.Guidelinesonhowto derivethesafetyclassofalaserwithconventionalfeatures(typicallypoint-likelight sources,Gaussianemissionproﬁle,singlemodeoperation)werepublishedpreviouslyandarealsocitedasexamplesin theIEC60825-1standard.However,comparedtotypicalpoint-like,single-modal lasersourceswithGaussianintensityproﬁle,VCSELdeviceshavespecialproperties thatmustbeconsideredhere.

Firstly,VCSELsexhibitamultimodalbeam profilewithlongitudinal,lateral,andpolarizationmodescompetingdependingon thedrivingcurrent.Thisresultsinahighly irregular,dynamicintensitypattern.Atdifferentcurrentsthespatialbeamprofilemay thereforevaryfromaGaussiantotop-hat ordoughnut-shapedemission.Additionally,alargedivergenceistypicalforVCSEL sourceswithangularwidthsinthe15°-20° rangeforbaredevices.Forlasersafety evaluations,thebeamprofilemustbean-

Figure1: FlowchartforlasersafetyassessmentaccordingtoIEC60825-1.

Asystemthatincludesafastphotodiode togetherwithanoscilloscope(e.g.pulsed VCSELtesterin Figure 2)isrecommended forcharacterizingthepulseform.Anearfieldcamerasystemtogetherwithaspectroradiometeristhemethodofchoicefor measuringthecentroidwavelengthand characterizingthesizeandshapeofthe apparentsource.Afar-fieldsystem(usingtheprojectionoftheVCSELsource onascreenandimagingwithacamera system)isrecommendedforthemeasurementofbeamprofile,divergenceangleand powermeasurements.Especiallyforpower measurement,thismethodisbeneficialbecauseitallowsforanalyzingintensity“hot spots”withthehelpofacameraimage (seee.g. Figure 3).Asoftwarealgorithm isusedtofindthepixelpositionwiththe maximalintensityaftersmoothingtheimage.Afterwards,thispixelisusedasthe centerofthecorrespondingareawithin 7mmdiameter,andthetotalpowerwithin theareaiscalculatedbymultiplyingbythe meanvalue.

Lastly,VCSEL-basedmodulesin3Dsensingaremostlyoperatedinpulsedmode, andoftenexhibitaquitecomplextemporalmodulation.Pulsedsourcesingeneral requireamorecomplexsafetyevaluation thancontinuouswavelasers,andforVCSELsourcesinparticularitisnecessary toapplyassumptionsandapproximations whenperformingtheseevaluations.

rameterssuchastheextensionofthelight sourceorthedistancetotheobserver.For pulsedsystems,pulselength,pulseenergyaswellasthedutycycleneedstobe known.

Theprecisiontowhichthesevaluesmust bedeterminedisdiscussedindetailin EN61040IEC1040 [3].Allmeasurement errorsandstatisticaluncertaintiesmustbe takenintoaccount,andshouldbeincluded inameasurementuncertaintybudget.

Theso-calledangularsubtense α isused toquantifythesizeofthesource.Theangularsubtenseoftheapparentsourceis determinedbythesmallestretinalimage sizethattheeyecanproducebyadjusting thefocallengthoftheeyelens.Thetwo simplestmethodstodetermine α areeither usingtheconservativedefaultvalueof1.5 mrad,resultinginartiﬁciallylowthresholds ormakinguseofsimpletrigonometryto estimatetheangularsubtenseforsurface emitters.Inthiscase,diameter d ofthe surfaceemitteranddistance r betweenthe

Secondly,VCSELsdesignedfor3Dsensingapplicationsoftencomeasarrayswith hundredsofsingleemitters.Incertainsituationstheymustbeconsideredas“extendedsources” [2]

Laserclassassignmentfollowstheprocedureshownin Figure 1.Thisparagraph aimstoexplaintheﬂowchartstep-by-step.

Theﬁrststepistoﬁndoutthesafetyrelevantparametersofthesource.An overviewofthemostimportantparametersandthemeasurementdevicesused todeterminetheseparametersisgivenin Table 1 and Figure 2.Thesevaluesdependnotonlyontheopticalpowerand wavelengthbutalsoongeometricalpa-

LaserSafetyAssessment Procedure

Allnecessarycorrectionfactors C and timepoints T giveninTable2andTable9 ofIEC60825-1mustbecalculated.Most ofthecorrectionfactorsdependonthe spectralregionoftheemission.Furthermore,correctionfactorsandtimepoints mayhavedifferentvaluesifasmallorlarge sourceisevaluated.Apointsourcewillbe imagedtoasmallspotbytheeyelens. Therefore,itcauseshigherintensitiesasan extendedsourcethatwouldcoveralarger areaontheretina.Itiseasytounderstand thattreatingthelasersourceasapoint sourceisalwaysaworst-caseassumptionandhencealwaysavalidoptionfor theevaluation.VCSELarraysareoftenextendedsources.Thisfactcanbeexploited toreachacertainlaserclassbymaintainingacertainemissionpower.Itwilldepend ontheindividualsituationwhethercompromisingamorerestrictedthresholdfora lesscomplexevaluationisappropriate.

alyzedforitsintensity“hotspots”thatare notnecessarilyinthecenterofthebeam (Figure 3).

DeterminationofSafety-relevant VCSELParameters

CalculationofNecessaryCorrectionFactorsandTimePoints

Averagepowerofapulsetrain

emitterandthemeasurementaperturegive theangularsubtense α: =2 tan 1( d 2r ) (1)

Theemissionlimitofasinglepulseiscalled AELsingle.Theaccessibleemissionof anygroupofpulsesdeliveredwithinany giventimemaynotexceedthe AEL for thatgiventime.Theassessmentmust considereverypossibleemissionduration. Therefore, AELsingle mustbeevaluated notonlyforsinglepulseduration,butalso forotherpossibletemporalstructuressuch asgrouporburstpulsewidths.

AELs.p.T (timebase)= AELT (timebase) PRF (2)

Table1: Safety-relevantVCSELparametersandrecommendedmeasurementdevices.

PRFeff = DCgroup DC t (3)

Forproductclassiﬁcation,themaximum levelofradiationpermittedwithinaparticularclassmustbedetermined.This so-calledaccessibleemissionlimit(AEL) isvalidonlyforachosenlaserclass,and attainsdifferentvaluesforextendedor smallsources.Beforestartingevaluation, theusermustchoosealaserclassand refertotheappropriatetable(Table3-7)in IEC60825-1.Thesetablesprovidevalues ofthe AEL forcertainrangesofwavelengthandemissiondurationoftheradiation.Often,the AEL mustbecalculated withthehelpofthecorrectionfactors C1 C7

Figure2: Measurementdevicesrecommendedfordatacollection.

Forarbitraryirregularpulsetrainsincluding varyingpulseamplitudeandbursts,the timebasemustbevariedfromtheshortest integrationtime Ti (seetable2in [1]),over allrelevantintervalsforthedifferentframes (e.g.bursts)to T

Inthewavelengthrange 400 1400 nmfor comparisonwiththermallimits,the AEL ofasinglepulsemustadditionallybemultipliedbycorrectionfactor C5 andiscalled AELs.p.train

Theaveragepowerofapulsetrainmust notexceedthe AEL ofasinglepulse ofthesamelength.Thelimitforasingle pulseofduration T iscalled AELT .Itis mostlyevaluatedforthetimebase.For comparisonreasons,thelimitforaverage powerisexpressedasenergyandtermed AELs.p.T .Foraregularseriesofpulses, thepulserepetitionrate PRF isusedfor conversionintoenergy:

AEL forsinglepulseenergy

Thebestapproachtodealwithanirregular seriesofpulsesisknowingthemaximum dutyfactor.Underthesecircumstances, itcanbeconsideredasaregularseries withaneffectivepulserepetitionrate.If theirregularseriescontainsforexample groupsofpulseswithpulsedurationt, theeffectivepulserepetitionratecanbe calculatedusingthedutycycleandthe groupdutycycleby:

CalculationofAccessibleEmissionLimits(AEL)

Inthecaseofpulsedsources,theprinciple applies,thattheaccessibleemissionofany groupofpulsesdeliveredinanygiventime mustbetakenintoaccount.Itistherefore necessarytoﬁndthemostrestrictiveoutof thefollowingthreerequirements:

Itdependsnotonlyonthepeakpowerand wavelengthbutalsoontheextensionofthe sourceanddivergenceofthelaserbeam.

Weightedsinglepulselimit

Anotherimportantparameteristheemissiondurationtobeconsideredforclassiﬁcation,calledthetimebase.Everypossible emissionduration,e.g.singlepulsewidth, withinthetimebasemustbeconsidered fordeterminationofaproduct‘slaserclass. Therearethreepossiblevalues(0.25s, 100s,500min)forthetimebase,dependingonthewavelengthandintendeduseof theproduct.VCSELdevicesusedfor3D sensingapplicationsareoftendesigned speciﬁcallyforlong-termviewing.Thus, thelongesttimebaseof500minutesmust oftenbeused.

Withthisvalue,itispossibletocalculate thecorrectionfactors C andtimepoints T

[1] InternationalStandardIEC60825-1Edition3.0 2014-05Safetyoflaserproducts-Part1:Equipment classiﬁcationandrequirements

Laserclassevaluationmustnotonlycomplywithallcorresponding AELs,taking intoaccountmeasurementerrorsandstatisticaluncertainties.Itmustalsoconsider anyrealisticallyforeseeablesinglefaultconditionduringoperation.Thismeansthat theusermustbeprotectedfromsystem failuresuchasvagabondinglaserlight, brokendiffusorsorjammedshutters.The frequencyofoccurrenceandriskofinjury arebothcrucialparametersthatdetermine

References

Dr.KarthikIYER wasaProductManager forVCSELtestingatInstrumentSystems GmbHinMunich(Germany).Hehasa strongbackgroundinelectricalengineering aswellasinVCSELtestingandcharacterization.

Dr.GüntherLESCHHORN joinedInstrumentSystemsGmbHbasedinMunich (Germany)asProductManagerin2012 andheadedtheproductmanagementdepartmentuntil2020.Today,heservesasa businessresearchercoordinatingbusiness activitiesoftheKonicaMinoltaSensing Group. mailto:leschhorn@instrumentsyst ems.com

Inafollow-uparticlethisgeneralapproach willbeappliedtotwoexamplesdemonstratingthetypicalchallengesofVCSELs. Inthisarticlewewillpresentastep-bystepanalysisonhowtoassessthelaser safetyoftypicalpulsedVCSELsandVCSELarraysasoftenemployedinconsumer electronicsandautomotiveLiDARapplications. ■

[2] TechnicalReportIEC/TR60825-13Edition2.0 2011-10Safetyoflaserproducts–Part13:Measurementsforclassiﬁcationoflaserproducts

Withthehelpofthecalculationsperformed inthelastparagraph,themostrestrictive AEL canbeidentiﬁed.Theexposureof theVCSELsourcemustbesmallerthan thismostrestrictivecriterion.Ifthisisnot thecase,thechosenlaserclasscannotbe assignedtotheproduct,andtheprocess ofﬁndingthe AEL hastobeperformed againusingthenexthigherlaserclass.

ConclusionandDiscussion

InordertoidentifytheexposureoftheVCSELsource,thefirstattemptshouldbe an“all-in-eye”approachbycalculating thetotallaserenergyperpulseusingthe measuredpeakpower.Ifthisisnotsufficient,onecananalyzethebeamprofilefor off-centerintensity“hotspots”(Figure 3). Takingthedivergenceofthebeamandthe accumulationofthehumaneyeintoaccount,thismayleadtoanexposuresmaller thanthe AEL

www.instrumentsystems.de

Correctionfactor C5 dependsontheeffectivenumberofpulses N inthepulsetrain. Acheckmustbeperformedtodetermine ifmultiplepulsesappearwithintheperiod of Ti.Inthiscase,thepulsesarecounted asasinglepulsetodetermine N andthe energiesoftheindividualpulsesareadded. Dependingonthesituation,therearedifferentformulaeforthecalculationof C5, dependingonwhetherthepulseduration t issmallerorlargerthan Ti

AELs.p.train = AELsingle C5 (4)

VCSELsourceshavecharacteristicpropertiesthatshouldbetakenintoaccount whenperformingeyesafetyassessment accordingtoIEC60825-1.Wehavediscussedthesespecialtiesandoutlineda guidelinetobefollowedforlasersafety classevaluation.

Figure3: Beamproﬁlewithoff-centerintensity hot-spot.

AboutInstrumentSystems InstrumentSystemsGmbH,foundedin Munichin1986,develops,manufactures andmarketsall-in-onesolutionsforlight measurementapplications.Itscoreproductsarearrayspectrometersandimaging colorimeters.Thecompany’smainﬁelds ofactivityareLED/SSLanddisplaymetrology,spectralradiometryandphotometry, aswellaslaser/VCSELcharacterization wheretodayInstrumentSystemsisone oftheworld’sleadingmanufacturers.The Optroniklineofproductsfortheautomotive industryandtrafﬁctechnologyisdeveloped andmarketedatitsBerlinfacility.InstrumentSystemshasbeenawholly-owned subsidiaryoftheKonicaMinoItaGroup since2012.

TianyuanCAO isanApplicationEngineer atInstrumentSystemsGmbHbasedin Munich(Germany).

FinalAssessment

whetherornotaneventmustbeconsideredandwhethersecuritymeasures(e.g. interlocks)arenecessary.

[3] EuropeanandInternationalStandardEN61040IEC 1040:1990Powerandenergymeasuringdetectors, instrumentsandequipmentforlaserradiation

MEASUREMENT HOWTOASSESSTHEEYESAFETYOFVCSELS–INTRODUCTION Issue93/Sept-Oct/2022 ©2022LugerResearche.U.|LEDprofessionalReview(LpR)|LightingTechnologies&Design 62 LED professional is the comprehensive publication and platform, connecting experts in the design, testing and production of the powered by Luger Research e.U. The Global Information Hub for TechnologiesLighting&Design More 45,000thanReaders GET YOUR FREE E-MAGAZINE SAMPLE www.led-professional.com/free Get your Free E-Magazine Sample

The GuideComprehensivetotheLightingWorld The Global Lighting Directory 2022 Published by LED professional & Trends in Lighting REGISTERFORFREE

Join CommunityDesignLightingthe monthlythetoSubscribe NewsletterLightinginTrends up-to-dateStay www.trends.lighting

NeuroscienceforArchitecture

OCTOBER31,2022

PRINTPUBLICATION

Theeditorsmakeeveryreasonableefforttoverifytheinformationpublished,butLugerResearche.U.assumesnoresponsibilityforthe validityofanymanufacturers,nonproﬁtorganizationsorindividuals claimsorstatements.LugerResearche.U.doesnotassumeand herebydisclaimsanyliabilitytoanypersonforanylossordamage causedbyerrorsoromissionsinthematerialcontainedherein,regardlessofwhethersucherrorsresultfromnegligence,accidentor anyothercausewhatsoever.Youmaynotcopy,reproduce,republish,download,post,broadcast,transmit,makeavailabletothepublic,orotherwiseuseLEDprofessionalReview(LpR)contentwithout priorwrittenconsentfromLugerResearche.U. ©2001–2022LugerResearche.U.–InstituteforInnovation&Technology–VATNo.ATU50928705,EORINo.ATEOS1000046213, CommercialRegisterFN316464p,RegionalCourtFeldkirch,Austria, Europe

QuestionsandComments

LpRPrinted&DigitalMagazine

• EUR78.80

ENQUIRIES|LpR94

NOVEMBER15,2022

LightingDesign

• BusinessIssuetoshareandusewithin organizations

LEDprofessionalReview(LpR) ISSN1993-890X

LpRDigitalMagazine

• Shippingcostsincluded

NOV/DEC2022|LpR94

https://www.led-professional.com/subscripti on

DEADLINES|LpR94

Copyrights–LugerResearche.U.

• 6IssuesperYear(Bi-monthly)

https://www.led-professional.com/advertise

LightingDesign

ImageCreditsforLpR#93/Copyrights

Issue93/Sept-Oct/2022

• eMagazine(PDFdownload)

• FullArchiveAccess (allpreviouseMagazineissues)

editors@led-professional.com info@lugerresearch.com

• PrintMagazineincludingshipping

CoverImage:TiffanyHouse(c)Lichtvision Design,Germany

SarahLuger +436802305445 hallo@moments-of-aha.com AccountManager ChristineLuger +4369911335520 c.luger@lugerresearch.com China,Hong-Kong LoloYoung +85297922081 lolo@castintl.com Germany ArminWezel +493052689192 armin@eurokom-media.de India

NOVEMBER30,2022

• EUR97.80

AnnualSubscriptions

Updates

TrendsinLightingBusiness

DIGITALPUBLICATION

Advertise

PriyankaRai +911244787331 priyanka.rai@binarysemantics.com SouthKorea Jung-WonSuh +8227858222 sinsegi@sinsegimedia.info Taiwan LeonChen +886225681786-10 Jeon@jkmedia.com.tw Benelux,France,Ireland,Scandinavia,UK ZenaCoupé +441923852537 zena@expomedia.biz USA&Canada LesleyHarmoning +12186866438 lesley@lhmediainc.com

JillThibert +12182802821 jill@lhmediainc.com>

■

Imprint

PostShowReport

IMPRINT SUBSCRIPTIONS,PREVIEW&PUBLISHER 66

PublishingCompany LugerResearche.U.|©2001–2022 InstituteforInnovation&Technology Moosmahdstrasse30,A-6850Dornbirn,Austria,Europe info@lugerresearch.com|www.lugerresearch.com P+435572394489|F+43557239448990

MATERIALDUE

• 6IssuesperYear(Bi-monthly)

Commentary

L+BEvent

FutureLighting Interview

• FullArchiveAccess (allpreviouseMagazineissues)

ADCLOSE

Pleasedon’thesitatetosendusyouropinionsoraskquestionsaboutarticlesyouhave read.Weappreciateyourfeedback. editors@led-professional.com

LightingNews,LpS-Digital

SarahToward +43557239448970 editors@led-professional.com

LightingDesignProject

TheresaKönig +43557239448970 editors@led-professional.com

• eMagazine(PDFdownload)

ElioA.Farina +43557239448970 editors@led-professional.com Art&Design

OCTOBER31,2022

PREVIEW

MarketReport

micro-LEDs

Electronics InnovativeLEDDrivers

Publisher SiegfriedLuger +4369911335570 s.luger@lugerresearch.com Editors Dr.GüntherSejkora +43557239448970 editors@led-professional.com

www.led-professional.com Showcase Your Lighting Excellence in 2022 Submit ourProposalYourtoEditors editors@led-professional.com

LED professional Review (LpR) – Sept/Oct 2022 – LpR#93

Articles inside

International Lighting News

Vertical Illumination

Professor Georges ZISSIS, Toulouse 3 University, France

Improve Alertness, Focus and Comfort with Biologically Effective Light

Adaptive-Driving-Beam Headlights A Collaborative Approach to Efficient Manufacturing of Complex Shapes Optical LSR Parts

Tiffany House

LpS Digital: Lighting Conference Exhibition 2022

Replacing Twilight with Good Light