ANALYSIS & OPINION

You're using a laser to do <em>what</em>?

Industrial and academic bodies unveiled the innovative ways they are using lasers within micro and nano processing at a recent conference for the Association for Industrial Laser Users (AILU).

Some of the applications included: producing a range of nano-sized components and particles, drilling and cutting parts that go into aeroplane engines and producing solar cells. The speakers also had very different views on what sort of pulsed laser beam is best.

The Industrial and research opportunities in laser micro and nano processing conference’s speakers also highlighted a few trends in the laser business. Speaking at the conference, Dr Nadeen Rizvi, general manager at Laser Micromachining, has noticed an increasing range of industries are starting to use lasers to manufacture devices, as he said: ‘Older industries are now taking up laser-based processing [and] we are working with a wide range of industries and subsequently materials for these industries.’

It’s not just the older, larger companies that are turning to laser manufacturing either, with smaller start-ups using the company’s facilities, according to Rizvi who added: ‘Lasers really bring down the time to manufacture for the early development phases [and] etching and other processes are just too expensive compared to lasers.’

‘Small companies with new ideas do not have deep pockets or the facilities to do this; we offer a way in for them by offering rapid and cost-effective prototyping,’ he added.

Mike Damzen of Midaz Laser identified another trend within the laser market. 'The laser market is being driven by decreasing feature sizes,' he said. 'And there has been an explosion in high tech consumer products, so although things are getting smaller there is also a lot more that needs to be processed within those small devices.’

So, to achieve this increase in information on smaller devices, Damzen added: ‘We need higher pulse rates and shorter wavelengths.’ And as the high-value manufacturing markets (like aerospace and automotive) require more sophisticated components, the lasers need to have a higher beam quality and flexible pulse rates to achieve this.

But not everyone agrees on which type of pulsed laser is best, be that nano, femto or pico, due to the range of applications for which each speaker is using lasers. Laser Micromachining is a small independent company providing laser manufacturing services to its customers and uses nanosecond lasers instead of femtosecond ones, as Rizvi said: ‘We can do 95 per cent of what we do with a nanosecond laser and do not need the femtosecond lasers yet.’

But Dr Walter Perrie, from the Lairdside Laser Engineering Centre at the University of Liverpool, is using a femtosecond laser to produce high-throughput micro-machining. Perrie said the shorter pulses are needed for his research as there can be problems with melting when firing a laser at a surface that may need to be patterned. But by going for shorter pulses, a solid to vapour transition is effectively achieved, which does away with the melting stage. ‘But we use mW instead of Watts and this is why industry has not taken it up,’ Perrie added.

After a few problems with the zeroth-order, Perrie has also developed a Spatial Light Modulator (SLM) to increase the throughput of the laser. The SLM is a very useful dynamic diffractive optic for laser micro-structuring, according to Perrie. The SLM combines with a 1kHz femtosecond laser to allow much more efficient use of the laser output, running at 0.3W at the moment, compared to an output of less than 50mW for similar systems.

Martyn Knowles, from Oxford Lasers, spoke on micro-machining of transparent materials with nano, pico and femtosecond lasers. Knowles is also a fan of the femtosecond systems too, as he said: ‘The best results have come from the femtosecond lasers.’ But he acknowledges that there is still a long way to go with this technology. ‘Ultrafast lasers often produce the best quality results, but it is still a new technology,' he added.

Mike Osborne from Optek Systems spoke on the ways in which laser processing of quartz optical components (for example for cutting of fibre optics) can be both rapid and accurate, allowing for the production of geometries that are difficult or impossible to achieve by other means.

Also present, was Heather Booth from Oerlikon, a solar panel producer, who uses lasers within her work and hopes that they can reduce improve the efficiency and hence improve the cost savings of using solar power. Booth said: ‘The cost to produce the solar technology needs to be lower than the current £ per Watts [for conventional energy sources] or there is no point doing out business.’

 

It’s academic

Using lasers to produce nanoparticles was also mentioned by some speakers, including Sohaib Khan a PhD candidate from the University of Manchester, who is trying to produce nanoparticles by firing a continuous wave, instead of the usual pulsed laser beams, at a substrate covered in a liquid. 

Zengbo Wang, who is part of the Laser Processing Research Centre at the University of Manchester, is also using particles within imaging by incorporating them with near-field laser processing techniques to try and beat the diffraction limit. Wang said: ‘To go beyond the diffraction limit we put the optics very close to the surface which we want to image.’

This is done by placing particles on the surface of the item to be imaged, and then using these as a Contacting Particle Lens Array (CPLA) to focus laser beams onto the surface. Wang added: ‘If we put a particle near the surface it acts like a lens and this offers a way for nanopatterning. The laser can also be out of focus as the particles act as a lens.’ 

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