SMS freeforms P. Benítez1,2, J.C.Miñano1,2, R. Mohedano2 1
UPM, Spain 2 LPI, USA
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design problems in Nonimaging Optics •
Bundle coupling: Source and target ray bundles are given. Maximum coupling efficiency is required. o o o o o
•
Collimators Condenser optics for a projector Light injection into an optical fiber Radiation sensors Photovoltaic concentrator
E(source) ≈ E(target)
Prescribed illuminance: The source ray bundle and the output illuminance distribution on the target are given. o o o o
Automotive headlights Street lights E(source) << E(target) RGB color mixing E = etendue = “size” of the ray bundle (in phase space) Backlights Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Why freeforms in Nonimaging Optics? • When source, target or volumetric constrains are nonsymmetric, symmetric solutions don’t work • Freeforms give you more degrees of freedom • Freeforms allow for fewer surfaces and parts because they can perform multiple functions
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design problems in Nonimaging Optics Prescribed illuminance
D. Michaelis et al., SPIE Vol. 7059, (2008) Pablo BenĂtez et al.
E(source) << E(target)
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
Design problems in Nonimaging Optics Bundle coupling
P. Benitez et al., “Squeezing the etendue”, in Illumination Engineering, (Wiley 2013) Pablo Benítez et al.
E(source) ≈ E(target)
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design problems in Nonimaging Optics Prescribed illuminance
E(source) << E(target) Pablo Benítez et al.
Bundle coupling
E(source) ≈ E(target)
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design methods in Nonimaging Optics 1. String method (1960’s) 2. Flow line method (1970’s) 3. Taylored Edge-ray method (1980’s) 4. Poisson bracket method (1980’s) 5. Lorentz geometry method (1990’s)
2D 2D and 3D
6. Point-source Differential Equation methods (1960’s) 7. Numerical optimization methods (1990’s) 8. Simultaneous Multiple Surface (SMS) method (1990’s) 2D = rotational or linear symmetry 3D = freeform Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 8
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
The SMS 3D • The method solves a partial functional differential equation • One full curve in one of the surfaces can be chosen (to partially control a third wavefront pair)
WFi1
optical path length L1
WFi2
optical path length L2
2 free-form optical surfaces
WFo2
WFo1
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 10
Input data
Input wavefronts
Output wavefronts
• Input wavefronts • Ouput wavefronts • Choose L1 & L2 • Type of surfaces (e.g., XX)
X = metallic reflection
R = refraction
I = total internal reflection
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 11
SMS - Chain
Input wavefronts
Output wavefronts
• Select P0 and N0
We choose P0 on the primary mirror Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 12
SMS - Chain
Input wavefronts
Output wavefronts
• Select P0 and N0 • Calculate P1 that matches L1
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 13
SMS - Chain
Input wavefronts
Output wavefronts
• Select P0 and N0 • Calculate P1 that matches L1 • Calculate P2 that matches L2 • Repeat the process for P3, P4, etc. • Go back to the initial point P0, then calculate the points P-1, P-2, etc. Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 14
SMS - Ribs
Seed Rib
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 15
SMS - Skinning
Seed Patch
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 16
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Example 1: Low beam headlamp design It is a prescribed illuminance problem
Specs defined by regulations (ECE, SAE) Typically 20 min/ max test points/ fields Gradient Specifications Homogeneity Car producer additional specifications
Horizontal Spread
Low glare values
Gradient/Cut-off
Elbow/ Shoulder Hotspot
Low foreground
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 18
Projected images of the source
Source
Pinholes
Images
HL Optical System
Screen at 25 m
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Projected images of the source
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Single freeform vs SMS freeforms H
H V V H H V V
Single freeform surface • Design controls the position of ONE point of the source image • It does NOT control its size, shape and rotation
SMS freeform surfaces • Design controls THREE points of the source image • Therefore, it DOES control its size, shape and rotation.
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 21
Freeform RXI automotive headlamp Seed rib
Spines Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 22
Freeform RXI automotive headlamp
Measured efficiencies: • 84% HB (Al mirror; AR coatings) • 75% LB (Al mirror; no AR coatings) US 7,460,985 & International patents pending Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 23
Freeform RXI automotive headlamp
Jewel Eye™ LED headlamps of the 2014 Acura RLX
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 24
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 25
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Unwanted effects
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013 27
Example 2: Color mixing collimator It is bundle coupling and prescribed illuminance problem
y
z
x
freeform collimator Pablo BenĂtez et al.
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
The metal-less Grooved-RXI 32 mm
1.3 mm
Two Total internal reflections at both groove sides
Pablo BenĂtez et al.
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
Statement of the problem WFB WFA
Groove edge line
r t
r vo r vi Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
D. Grabovičkić, et al. Opt. Express 19, (2011)
Color Mixing V-groove back surface
LEDs
1.25 mm
h -h
R
G
G
B
0.1 mm
Analysed with
Metal-less RXI, true colour far field pattern
Conventional RXI, true colour far field pattern
Pablo BenĂtez et al.
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
Color Temperature & dimming LEDs
V-groove back surface
1.25 mm WW
CW
CW
NW
0.1 mm
Analysed with
Metal-less RXI, true colour far field pattern
Conventional RXI, true colour far field pattern
Pablo BenĂtez et al.
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
Prototypes
grooved RXI
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Measurements
LED
LED On
LED Off Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Measurements Simulated intensity distribution
Measured intensity distribution
• Measured maximum intensity 22 cd/lm (29 cd/lm simulated) • Measured efficiency (in ±20º)= 96% of simulated value Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Application of SMS method in Imaging SMS 2D (rotational optics)
SMS 3D (free form optics)
Image plane
Up to 6 aspheres
Up to 2 free-forms
J. Infante, PhD dissertation, 2013
L. Wang, PhD dissertation, 2012
Pablo BenĂtez et al.
Spanish Optical Designersâ&#x20AC;&#x2122; Meeting, Oct 3, 2013
Advantage of freeforms
J.C. Miñano et al., OSA freeform incubator meeting, Washington D.C. (2011)
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Imaging with high aspect ratio SMS lens
SMS lens + optimization
F.Duerr et al., Opt.Express 20,10839–10846(2012)
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Imaging with high aspect ratio Optimised rotatonal lens RMS < 11 µm
SMS lens + optimization RMS < 6 µm
F.Duerr et al., Opt.Express 20,10839–10846(2012)
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Index • • • • • •
Introduction SMS 3D design process Example 1: Automotive headlamp Example 2: Color mixing collimator Example 3: Imaging Conclusions Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Conclusions • SMS 3D design method allows for designing two freeform surfaces using up to three wavefront pairs. • SMS 3D controls size and orientation of source projected. • SMS 3D can handle prescribed illuminance and boudle cupling problems with extended sources, including color mixing • SMS freeforms are also excellent starting points for optimizations Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
LEGAL NOTICE Devices shown in this presentation are protected by the following US Patents and US and International Patents pending: 6,639,733; 2001069300; CA2402687; 2003282552; 6,896,381; 20040246606; 20050086032; 200501295; PCT publication WO/2007/016363
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Thank you!
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design problems in Nonimaging Optics Prescribed illuminance
D. Michaelis et al., SPIE Vol. 7059, (2008)
Bundle coupling
P. Benitez et al., “Squeezing the etendue”, in Illumination Engineering, (Wiley 2013)
Pablo Benítez et al.
Spanish Optical Designers’ Meeting, Oct 3, 2013
Design problems in Nonimaging Optics Prescribed illuminance
E(source) << E(target) Pablo Benítez et al.
Bundle coupling
E(source) ≈ E(target)
Spanish Optical Designers’ Meeting, Oct 3, 2013