Why Metrology is Important

Research Highlights

The Hub research programme is split into two distinct phases. Phase One, taking place over years one to four, concentrated heavily on the development of the fundamental science and technology necessary to overcome significant technical and physical challenges. This largely consisted of focussed teams working independently in specific areas.

From year four onwards, the Hub has moved into Phase Two research which focusses on drawing these separate threads together to design and deliver groundbreaking new measurement devices and techniques. In addition to the core research programme, the Hub has identified new, complimentary research and funded them as additional work packages. The research outcomes from these new work packages will be incorporated into the Phase Two programme.

Research Programme Phase One

The first phase of the Hub research programme focussed heavily on the development of fundamental technologies necessary to create the next generation of measurement devices and systems. The programme was split into two themes:

Theme I: Embedded Metrology

Embedded Metrology will build sound technological foundations by bridging four formidable gaps in process- and componentembedded metrology.

This covers: physical limits on the depth of field; high dynamic range measurement; real-time dynamic data acquisition in optical sensor/instruments; and robust, adaptive, scalable models for real-time control.

Theme II: Metrology Data Analytics

Metrology Data analytics will create a smart knowledge system to unify metrology language, understanding, and usage between design, production and verification for geometrical products manufacturing; Establishment of data analytics systems to extract maximal information from measurement data going beyond state-of-theart for optimisation of the manufacturing process to include system validation and product monitoring. systems using sensor networks with different physical properties under time-discontinuous conditions. Optics - Novel non-contact measurement techniques such as Interferometry, Deflectometry and Fringe Projection which are essential for creating the next generation of sensors necessary to enable fully embedded metrology

Machine Tool and Robotics – Methods of utilising advanced metrology techniques and sensor networks to achieve real time control of manufacturing systems, improving performance and capability.

Mathematics and Data Analytics – The vast quantities of data created by embedded sensor networks will require the development of a mathematically based language for metrology and the creation advanced data analytics systems to rapidly extract maximal information from the measurement data.

WP1: Basic Non-diffractive Interferometry

Aim: to investigate methods of extending dynamic range in optical sensors which is a key criterion for enabling the integration of sensors for embedded metrology by allowing more flexibility in deployment and widening applicable measurement scenarios. The planned work focusses on increasing depth of focus (DOF) using nondiffracting beams to increase dynamic range. This WP is a contributor to the major Hub aim of transferring conventional lab-based metrology to fully embedded metrology.

Publications: 10 Journal Papers, 2 Conference Papers, 1 Book Chapter

Key outputs:

• Bessel beam generating

OCT apparatus has been successfully constructed for implementing spectraldomain OCT

• Modelling work on non-diffracting Bessel beams has generated an understanding that its applications to measurement systems involving specular characteristics would be challenging.

• Fourier domain OCT apparatus constructed that can operate with both conventional/ axicon objective to enable performance comparisons.

WP2 Novel Fringe Projection Technologies Across Scales

Aim: to investigate highspeed (>108 coordinates s-1) fringe projection systems for robot guidance and jigless assembly; to explore stereo deflectometry based measurement systems for noncontact specular freeform surface measurement, and in-situ quality control with nanometre form accuracy. This WP aims to support embedded metrology for assembly platform.

Publications: 17 Journal Papers, 4 Conference Papers

Key outputs:

• A high-speed projection and acquisition system has now been implemented in the laboratory with fullframe acquisition rates of 3.5 kHz.

• A phase mask design algorithm has been developed, based on a polychromatic Fourier optics model.

• A direct phase measuring deflectometry system which can measure specular objects with isolated and/or discontinuous surfaces has been developed.

• A triple sensor deflectometry system has been developed with combined dual scale field of views to tackle surfaces with local fine structures and large measurement field.

WP3 Spectral Interferometers for Multi-property Measurement

Aim: to explore spectral interferometry as the basis for creating novel sensors operating at both long-scales (metres) and nano-scales. For absolute distance, vibration and surface topography measurement at the longscale, the key targets are rapid coordinate measurement with low system cost. At the nano-scale the challenge is to produce an ultraminiature sensor-on-a-chip for absolute distance, surface profile and layer thickness measurement. This WP aims to support embedded metrology ‘cross-scale’ in high-value manufacturing.

Publications: 2 Journal papers

Key outputs:

• A bench-top 3-switch prototype Adaptive Delay

Line (ADL) has been set up using bulk optical components.

• A method for surface roughness measurement using FSI has also been proposed, based on

Fourier analysis of the interference signal, and has been tested using data from a hyperspectral interferometer.