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Tenth Microprocessing Workshop

Industrial and research opportunities in laser micro and nano processing
4 and 5 June 2008 - Daresbury Laboratory, Warrington

Photo of the workshop speakers (L to r) Sohaib Khan (NWLEC); Malcolm Gower (Chair); Walter Perrie (NWLEC); Richard Murison (Pyrophotonics); Guido Hennig (MDC Max Daetwyler); Heather Booth (Oerlikon); Sasha Weiler (Trumpf); Clive Grafton-Reed (Rolls-Royce); Martin Knowles (Oxford Lasers); Roy McBride (PowerPhotonic); Nadeem Rizvi (Laser Micromachining). Missing from the photo are Qin Hu (University of Cambridge); Mike Damzen (Midaz Laser); Zengbo Wang (NWLEC); and Mike Osborne (Optek Systems).

At the beginning of June Daresbury Laboratories saw the tenth anniversary of AILU’s annual micro-processing meeting. To celebrate the event, AILU joined with the North West Laser Engineering Consortium (NWLEC) to provide a two day event. It saw the launch of AILU’s Special Interest Group, the Micro:Nano Group. The Micro:Nano Group is a Photonics KTN Special Interest Group managed by AILU as part of its commitment to promote power photonics in microprocessing applications. Over seventy delegates, including a strong student contingent from the Universities of Liverpool and Manchester, came to network and to hear presentations from international companies and academia. This report relates only to the first day, which was largely organised by AILU.

The workshop was chaired by Malcolm Gower, who gave a short introduction to the subject, pointing out the predicted near-term growth of laser micro-processing machines and emphasising that the aggressive drive for increasing miniaturization of components will continue to push the spatial limits of manufacturing technologies into the nanometre regime.

The invited speaker, Guido Hennig of MDC Max Daetwyler AG (Switzerland), described the large scale laser micro-structuring of gravure print rollers and the importance of producing the desired size and capillary action to release the optimum amount of ink without wastage. In doing so he provided an excellent example of the industrialisation of a state of the art (laser) processing.

Qin Hu from the University of Cambridge discussed the forming and production of micro and nano-scale components. The work is part of a £9 million funded 4-year Grand Challenge project to develop true-3D, multi-material and miniaturized technologies and then transfer the technology from the research base to a viable industrial process. Currently she is focused on a new 3-D manufacturing approach termed 'Laser Print Forming' that combines the merits of nano-technology and ultrafast laser machining.

Nadeem Rizvi of Laser Micromachining Limited spoke on laser-assisted manufacturing for emerging technology sectors. With a wide range of different lasers of many wavelengths from CW to ultrafast pulse duration available in-house, he described their usefulness and versatility for prototyping and low volume medical device manufacture.

Walter Perrie of NWLEC gave a presentation on high throughput parallel micromachining using a femtosecond laser. He described the possibilities of using a computer-generated hologram produced on a Spatial Light Modulator (SLM) to control beam profile and, for parallel processing, produce many lower power beams for laser machining.

Richard Murison from Pyrophotonics in Canada described the technology and micro-machining applications of their fibre laser, which offers complete pulse shape control. He explained how this allows full variability parameters to establish the optimum conditions for each material/process. The source would initially be of particular interest to research groups investigating optimal parameters for different applications.

Mike Damzen of Midaz Laser discussed their micro-slab DPSS lasers, which offer high power and pulse rates for high speed micromachining. The Midaz DPSS laser has a side-pumped microslab architecture that allows very high average power scaling (to approximately 100 W) with excellent fundamental Gaussian beam quality; the laser is compact and has high gain and efficiency. Pulse rates in excess of 1MHz are available, with peak powers of about 1MW.  A conversion efficiency of almost 60% is achievable for generation of a variety of wavelengths in the visible and UV.

Zengbo Wang from NWLEC described the use of near field imaging for sub-wavelength processing. Near-field systems involve interference of evanescent waves. Applications include nano-patterning using contacting particle lens arrays (CPLA); illustrations included arbitrary shapes on a nano-scale using oblique angles of incidence. He claimed that the CPLA technique competes favourably with microlens array systems currently in use.

Potential applications include large area surface roughening, micro and nano fabrication of periodic arrays and for data storage.

Martyn Knowles from Oxford Lasers gave a review of micromachining of glass and other transparent materials with nano, pico and femtosecond lasers. Photonics applications rely heavily on transparent media (in particular glass, fused silica, sapphire, PMMA and polycarbonate), making laser processing of transparent media on the milli, micro and nano-scale increasingly important. Restricting his talk to UV and ultrafast laser processing he discussed the properties of UV laser processing and the interaction of ultrafast laser beams with the materials they process.

Mike Osborne of OpTek Systems discussed CO2 laser processing of micro-optics. OpTek produce many systems and automate the process to ensure good yield and reproducibility. He provided examples to show how CO2 laser processing of quartz optical components can be rapid, flexible, reproducible and accurate, including the production of geometries that are difficult or impossible to achieve by other means. Laser cleaving is a fast accurate process, including the cleaving of photonic crystal fibre.

Clive Grafton-Reed of Rolls-Royce provided a brief insight into their laser manufacturing technologies. Applications included laser drilling, cutting of combustors and turbines as well as welding of combustors and fans. Manufacture of compressors includes laser peening of fan blades; lasers are also used for additive manufacture, local heat treatment and cladding, and for cleaning surfaces before repair. Looking to the future, Clive highlighted laser beam pulse shaping and the tuning of energy distribution during the manufacturing process (e.g. during drilling, to reduce recast, micro-cracking, oxide and HAZ and thereby to give better repeatability and hole quality). Rolls-Royce are looking to broaden their use of lasers in production and are keen to acquire more wavelengths and different powers including ultra-short pulse length lasers for “cold” processing at economic rates. Fibre lasers are particularly interesting for welding and when the price matures Clive wants to see them on standard platforms.

Sascha Weiler of Trumpf (DE) discussed industrial micro-machining with high average power picosecond lasers and the ability of these sources to achieve cool or even cold processing and showed impressive results with the new Trumpf TruMicro series of high average power picosecond lasers working at near-IR, green and UV wavelengths with good beam quality (M2<1.3).

Roy McBride of PowerPhotonic spoke about the production of freeform refractive micro-optics by direct laser writing.  PowerPhotonic custom micro-optics fabrication is produced on a fused silica substrate using a direct write technique (thereby avoiding tooling costs) and subsequent laser polishing. As a practical example, he showed wavefront mapping the output of high power diode lasers at full operating power where the results were translated into the specification for a wavefront compensating micro-phase plate, producing a high quality output beam.

Heather Booth of Oerlikon reviewed laser applications in photovoltaic (PV) cell manufacture. Heather described the market position, the forecast of technology adoption and the need for capital expenditure per Watt of power to be reduced in order for lasers to be competitive. Drivers for the adoption of new energy sources include the rising cost of energy and environmental concerns. Market demand has produced an exponential growth in PV manufacture and the forecast is for it to continue. Oerlikon Solar are working towards the goal of achieving grid parity by innovating in three areas: (i) Reducing the $/W to make laser technology more competitive; (ii) improving module efficiency; and (iii) improving the economics of scale by using larger fabs. Lasers currently find applications in many areas in the production of PV cells, including patterning, border deletion, edge isolation, ID marking, wrap-through, cutting, doping, defect repair and interconnection. However, most of these applications are only partially adopted or are used only on a pilot line.

Sohaib Khan of NWLEC described the use of CW fibre laser for the production of nanoparticles. The production rate is high and of interest for commercial production as well as for research in-house. Pulsed laser technology is used to make variable sized particles for use in many applications. Applications include: use as an energy converter in solar cells; gas or temperature sensors; solid oxide fuel cell; UV protection; waste water purification; and catalysts and catalyst supports.

AILU thanks go especially to Martin Sharp (NWLEC) who provided all the local organisation for the event and Malcolm Gower who provided valuable advice on the programme structure.

If you would like to join the Micro:Nano Special Interest Group and shape our activities please contact thr AILU Office.


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