Frequency-comb enabled metrology for manufacturing

This proposal aims to transition today's highest precision laser technology -- optical frequency combs -- from the lab to the factory, establishing the technique of dual-comb distance metrology as an enabling technology for manufacturing the next generation of precision-engineered products, whose functionality relies on micro-/ nanoscale accuracy.

Optical techniques form the basis of critical industrial distance metrology, but face compromises between accuracy, precision and dynamic range. Time-of-flight methods give mm accuracy over an extended range, while interferometric trackers achieve nm precision but with no absolute positional accuracy. By developing novel dual-comb metrology techniques, this project will bridge the gap between precision and extended-range accuracy, providing traceable nm precision, with almost unlimited extended-range operation. For manufacturing industry, comb metrology therefore addresses the important problem of how to verifiably fabricate macro-scale objects with nano-/micro-precision.

Building on Heriot-Watt's frequency-comb expertise, we will develop Ti:sapphire and Er:fibre dual combs, with the aim of demonstrating nm-precision controlled-environment metrology using Ti:sapphire, and micron-precision free-space ranging using eye-safe Er:fibre. Besides their novel applications in precision metrology, by implementing new efficient and compact diode-pumping schemes our research will extend laser comb technology in a way that makes these systems suitable for deployment in a wide range of environments outside the research lab, for example as modules in a precision quantum navigation system.

Our project integrates key academic and industrial partners who will contribute resources and expertise in lasers (Chromacity), precision micro-optics (Powerphotonic), industrial metrology and manufacturing (Renishaw), ultra-precision metrology (EPSRC Centre for Innovative Manufacturing in Ultra Precision and CDT in Ultra Precision) and applications in large optics for astronomy (STFC UK Astronomy Technology Centre). The commitment of our partners is evidenced by >£300K of support, including £145K of cash which will be used primarily to support two EPSRC EngD and PhD students recruited to the project.

The project aligns closely with the EPSRC's Manufacturing the Future challenge theme and the ICT Photonics for Future Systems priority, as well as the EPSRC's training agenda, by engaging EngD and PhD researchers from the CDT in Applied Photonics and the CDT in Ultra Precision. More generally, the project will support the UK's high-precision manufacturing and metrology communities, with potential academic and industrial benefits.

By the end of the project we expect to have demonstrated and evaluated dual-comb distance metrology in a variety of practical manufacturing contexts (machine calibration, in-process control, finished-product inspection), and to be in a position to translate the technology into our industrial and academic partners.

Our research programme will produce immediate academic impacts, with industrial, economic and societal impacts emerging over a longer timescale.

1. Impacts on Industry
More broadly, we expect the research to deliver sustained impact in the form of new metrology paradigms taken up by industrial early adopters to solve acute problems in precision manufacturing.

As an innovative new methodology, dual-comb distance metrology has considerable potential to address measurement problems across a variety of sectors and disciplines, for example: (i) in manufacturing, where the automotive, defence and aerospace sectors have fine tolerances for large critical parts, benefiting from machine-tools which are indexed using a laser comb; (ii) in the energy sector, where large turbine blades must be accurately profiled to verify they have been manufactured correctly, benefiting from the extended-range metrology aspects of our proposed research; (iii) the environmental protection sector, in which a range-gated spectroscopic approach, as is possible using dual-comb spectroscopy, will provide multi-species chemical monitoring.

Our named industrial partners will benefit from the project outcomes in different ways. By licensing intellectual property generated at HWU, each of our partners stands to benefit commercially: Renishaw, via access to a disruptive metrology technique not available to its competitors; Chromacity, by licensing laser technology which would open up new markets in metrology and sensing; and Powerphotonic, for whom micro-optical beam shaping of single emitters may become a significant area of growth driven by DPSS laser replacements and diode-laser projection systems.

More broadly, the development of a UK capability in dual-comb precision metrology for manufacturing from a small initial group of industrial stakeholders could lead to wider industrial adoption of the technique, with longer term commercial benefits to UK manufacturers from this emerging technology (see Case for Support, Section 3.4).


2. Impacts on Project Researchers
Through the training and personal development of two CDT students (one EngD and one PhD), the project will support UK industry's requirement for highly skilled researchers in applied photonics. The named Researcher Co-investigator, Dr. Zhaowei Zhang, will also be developed in his project management skills through mentorship with Reid and Faccio, his professional network with industry and access to formal staff development courses relevant to his personal development needs.

3. Impacts on Academic Researchers
We expect to generate new scientific and engineering knowledge in the separate areas of laser comb technology and applied precision metrology. Through the dissemination of our work in appropriate technical journals and conferences our results will influence the practice of other researchers in areas including laser development, frequency comb techniques, applied metrology and manufacturing research.


4. Socio-Economic Impacts
The precision and absolute accuracy provided by dual-comb metrology makes it realistic to expect the technique will have a positive societal and environmental impact by reducing waste and improving yields / productivity in manufacturing processes.

Our public engagement plan (see Pathways to Impact) includes activities which will reach the general public, increasing public awareness of the role of photonics and the value of precision manufacturing to the UK.