Frequency-comb metrology for manufacturing: Diode-pumped Ti:sapphire frequency combs for precision distance metrology

Introduction
Frequency combs are the world’s most precise laser sources, with intrinsic noise measured at the 10-19 level, and celebrated in the 2005 Nobel prize to Jan Hall and Ted Haensch for their early work in developing this technology.

This project is one of 3 offered in support of a new £1M initiative jointly supported by UK industry and the EPSRC to develop frequency combs to enable innovative ways to measure distance in industrial manufacturing contexts – from the curvature of mirror segments of large telescopes, to the position of machine-tools or the shape of turbine blades or aeroplane fuselages.

Technical context
This and the other 2 adjacent doctoral projects will investigate & develop complementary solutions to a distance measurement approach known as "dual-comb distance metrology", with the long term intention being to bridge the gap between precision and extended-range accuracy, providing industry with traceable & universal length-metrology. In a nutshell, we want to demonstrate an optical measurement approach that can measure the position of objects at considerable distance without sacrificing accuracy.

Project description: Diode-pumped Ti:sapphire frequency combs for precision distance metrology
The most accurate laser frequency combs are those based on the solid-state gain crystal Ti:sapphire, which normally requires an expensive, water cooled green laser pump source. At Heriot-Watt we have obtained direct pumping using green laser diodes, a potentially game-changing technology. This project will develop laser-diode pumped Ti:sapphire frequency combs, leveraging their size and modulation bandwidth to develop versatile and cost-effective combs that can be multiplexed to achieve ultra-high-precision distance metrology using cooperative targets such as retroreflectors. Beginning with the development of novel Ti:sapphire dual-comb systems, the project will move towards applying these in collaboration with our industrial partner Renishaw for applications in quantifying machine-tool errors. The student will be registered at Heriot-Watt University where they will spend the majority of their time. Renishaw PLC is based on the same campus as Heriot-Watt.

Location
Heriot-Watt is based in a modern environment on the outskirts of Edinburgh, with excellent transport links to the centre of one of Europe’s most exciting cities. Heriot-Watt was recently awarded (November 2013) an EPSRC Centre for Doctoral Training in Applied Photonics, cementing Heriot-Watt’s reputation as a centre of excellence in photonics, and providing PhD students with an even more attractive environment for study, as well as enhanced training opportunities.

Heriot-Watt Institute of Photonics and Quantum Sciences (IPAQS)
IPAQS is a thriving environment for PhD research, having a total of 160 academics, postdocs, PhD and EngD students working full-time in the general photonics field. It’s a friendly collaborative environment where staff and students freely interact -- not least at Friday morning coffee and donut sessions.