Lasers are rapidly becoming more useful - they are widely available at shorter wavelengths, emitting shorter pulses and at higher energies and powers than ever before. These characteristics make them especially useful for several industrial applications such as velocimetry, micro-machining and welding, where the beam characteristics delivered to the workpiece are critical in determining the success and efficiency of the process. Unfortunately, the very characteristics that make these laser pulses so useful - their short pulse lengths, low wavelengths and higher energy and power - make them absolutely impossible to deliver using conventional fibre optics. This means that those wishing to exploit the new laser systems would currently have to do so using bulk optics - typically, several mirrors mounted on articulated arms to deliver the pulses to the workpiece.We propose to use an alternative optical fibre technology to solve this problem. Hollow-core fibres which guide light using a photonic bandgap cladding have roughly 1000 times less nonlinear response than conventional fibres, and have far higher damage thresholds as well. In previous work, we concentrated on longer nanosecond pulsed lasers, and demonstrated that we could use these fibres to deliver light capable of machining metals. However, it is with the picoscond and sub-picosecond pulse laser systems now becoming more widespread that the hollow-core fibres really come into their own. For these shorter pulses, transmission through conventional fibres is limited not only by damage, but first by pulse dispersion and optical nonlinear response. These problems can only be surmounted using hollow-core fibre - no competing technology has come even close.Our work programme has several strands, with the common objective being to devise systems capable of delivering picosecond-scale pulses through lengths of a few metres of fibre, at useful energies and powers. To do this, we need to be able to efficiently couple light into the fibres and transmit them, single-mode, over a few metres of fibre with low attenuation. We plan to focus our attention on doing this in the wavelength bands around 1060nm and 530mn, and to investigate the possibility of extending the work to shorter wavelengths. We will work closely with several collaborators from the industrial/commercial sector, ranging from a UK-based supplier of relevant laser systems through to a company developing machining systems and indiustries which actually use such systems. In this way, we plan to provide UK-based industry with a competitive edge on teh global stage, by providing them with access to an academic area where the UK is an acknowledged world leader.

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Manufacturing with lasers has advanced from the purely science fiction ideas of the 1950's and 60's to be a real world, critical step, in the manufacture of an enormous range of products. Over the years a range of new techniques and processes have been developed in research labs and companies across the world. One of the more important of these has been the development of beam-shaping technology. Laser processing of material is driven by transfer of energy from the laser beam into the material, and can be a mixture of thermal, photo-chemical and optical non-linear effects. By changing the shape of a laser beam where it impacts a material it is possible to mould how and where energy is transferred. This then allows for more precise control of the laser-material interaction and hence of the manufacturing process itself. This has led to improvements in the way cutting, welding and similar processes work with improvements in quality and efficiency. However these beam-shaping technologies are limited. They only shape in two dimensions, i.e. in a single focal plane. This is not a big problem for "surface processes" as the plane at which the laser beam is formed into the right shape can be made, with some care in focussing the beam, to be the surface of the material. However for materials with an irregular shape, imprecise thicknesses, or that are at least partially transparent to the laser, this is a challenge. It is also a challenge when trying to take advantage of the range of exciting new technologies based on non-linear phenomena. Non-linear laser processes typically limit the laser material interaction to only those regions of the laser beam where there is an extremely high intensity i.e. at the focus. By moving the focus inside the material it then possible to manufacture from the inside out. However, because the light interacts with the material not just on the surface but throughout the focal volume two dimensional beam shaping is insufficient; full 3D control is instead required. Within this research project we will take advantage of the wave-nature of light. Through careful shaping of a glass optic it is possible to bend different parts of a laser beam to overlap in a controlled manner. As the beams overlap they will interfere creating regions of high and low energy. Though careful calculation it is possible to manipulate this with each optic designed to give a precise interference pattern which results in a specific energy distribution; to shape the beam in three dimensions. By shaping the laser beam throughout the focal region it will be possible to open entirely new methods of manufacture from more effective means to cut toughened glass (like mobile phones or iPads), dice and drill semiconductors (for computer chips), make precision medical devices, and create new and much more effective surgical procedures. The potential applications are truly enormous, transformative and will change how and what we can manufacture.

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.

The unique properties of light have made it central to our high-tech society. For example, our information-rich world is only enabled by the remarkable capacity of the fibre-optic network, where thin strands of glass are used to carry massive amounts of information around the globe as high-speed optical signals. Light also impacts areas of our society as diverse as laser-based manufacturing, solar energy, space-based remote sensing and even astronomy. One area where the properties of light open up otherwise-impossible capabilities is medicine. In ophthalmology for example, lasers are routinely used to perform surgery on the eye through corneal reshaping. This involves two different lasers. In the first step, a laser producing very short pulses of infrared light cuts a flap in the front surface of the eye to provide access. In the second step, another laser producing longer pulses of ultraviolet (UV) light sculpts the shape of the cornea and correct focusing errors. The flap is then folded back into place so that the cornea can heal. The two very-different laser systems in that example illustrate an important point: the effects of light on human tissues are highly-dependent on the specific properties of both the light and the tissues involved. To sculpt the cornea, the laser wavelength of 193 nm is in the deep UV region of the electromagnetic spectrum, much shorter than the visible range (380 - 740 nm) we are familiar with. This is because (unlike visible light) it is very efficiently absorbed by the cornea, so that essentially all the energy of the light is deposited at the surface. Thus only a very thin layer of tissue (a few microns thick) is removed, or "resected", with each pulse of light, facilitating very-precise shaping of the cornea and accurate adjustment of its focusing properties. 193 nm light can be generated by an ArF excimer gas laser, a >40 year-old technology producing a poor-quality low-brightness beam of light. This is suitable for corneal reshaping, but not for a range of other important therapies requiring higher-quality deep UV beams. Unfortunately, alternative ways to generate such short wavelengths are non-trivial, resulting in complex and expensive laser systems not suitable for widespread clinical uptake. U-care aims to address this gap by exploiting cutting-edge techniques in laser physics. We will develop new sources of deep UV light which will be highly compact, robust and low cost. We will develop ways to deliver this light precisely to tissues, and work to understand in detail the biophysical mechanisms involved. Our efforts will focus on new therapies that target some of the biggest challenges facing medicine: cellular-precision cancer surgery, and the emergence of drug-resistant "super-bugs". Importantly, U-care will involve engineers and physical scientists working in close collaboration with clinicians and biomedical scientists to verify that the therapies we develop are effective and safe. By doing so in an integrated manner, we will drive our deep-UV light therapies towards healthcare impact and widespread use in the clinic by 2050.