TECHNOLOGY
CO2
LASERS
New avenues C
CO2 lasers have a
future with organics as Rob Coppinger discovers
arbon dioxide lasers represent a mature technology, and the expansion of competing
technologies into their traditional market is much reported, but this staple of the job shop is finding that industry’s more exotic composite materials are opening up new markets. Andrew Held is the director
of marketing for Coherent’s CO2 business unit. He told Electro Optics: ‘What we’re doing here is tailoring our lasers to new applications and materials. That’s where CO2
– an
older technology – is finding new applications. The newer materials are ideally suited to 10 microns.’ Held describes an emerging market
where fibre lasers, which have seen a lot of growth, are not viewed as ideal because users find no material interaction at one or two microns. ‘So when you skip to 10 microns we have this interesting wavelength that reacts well with lots of material, especially glass, ceramic and new film-like materials,’ explains Held. Coherent’s approach is not to just tweak existing lasers to tackle the new materials that are driving the new applications, but to modify the lasers in significant ways.
As CO2
One example is power control. lasers are big in volume,
with heavy electrodes using lots of different materials that expand and contract with the heat generated, their power stability is poor – about five per cent. Held explains that reducing
that poor power stability was a goal. ‘It has to do with this massive chunk of aluminium that is expanding and contracting – and that has been acceptable in the past when cutting materials, leather for example, but that power stability is not acceptable in more modern materials so we have stabilise the laser with a special electronic closed loop. We have got power stability down to 0.5 per cent.’ The power control is enabled by a faster control loop, with a millisecond timeframe that allows users to have power control – not only with continuous wave, but also when they turn the laser on and off quickly. ‘When people are cutting something, from one part to another, it is important to have that fast power control,’ says Held.
peak power, wavelength stability. If you talk about what is new, these applications happen so quickly that we look at the application in the design phase,’ explains Held. ‘We’re actually working with customers in the design phase and test the application when the thing is wired and held together with C clamps and such, that paces the development and design of the laser itself.’ Held’s engineers also find that specific parameters in the beam quality come to the fore when applied early to an application. ‘Tying the application to the design and development is something new for
The approach now is to
have the laser developed with regards to the customers’ needs
Reliability is always going to be important, and Held says it is not only about customer satisfaction any more. Reliability is a cost control exercise for Coherent. ‘Lots of lasers are going to Brazil. This is where reliability is so important. It costs a lot to bring them back for servicing.’ These significant modifications do not follow the typical engineering cycle. While a typical design process involves the marketing department giving engineers the specification, the engineers developing it, passing it to sales and getting feedback from customers, the approach now is to have dedicated application laboratories so the laser is developed with regards to customers’ needs. ‘Our application lab in Bloomfield does not process coupons for customers, but is working with the design team during the design process of the laser.’ That application-linked development focuses on several factors. ‘We look at pulse width,
20 ELECTRO OPTICS l FEBRUARY 2013
us. It would have always made sense, but in the past materials and process demands were not as high as they are today.’ Today, with films, ceramics, glass and composites, for example, Coherent finds its customers’ materials are changing very quickly. The flat panel display market is a sector where this process is moving
fast. ‘They are getting bigger and slimmer and the way to do it is to combine those layers. How do you cut those?’ says Held. ‘When you look at your flat panel display you may have 30 to 40 layers of materials in there, and some are discrete, but what they want to do now is combine those.’
How those layers are formed is also changing, giving lasers new challenges. A layer in a flat panel display, which had been a film that was then discreetly attached to the glass or acrylic, is now a true combination of the two that has to be cut at the same time. ‘Now you’re cutting glass and the film, or the film on the glass, and that is really pushing the requirements of the CO2
lasers – so we developed the lasers with that in mind,’ adds Held. Sometimes customers are able to meet Coherent half-way. Instead of developing the laser to match the absorption wavelength best- suited to the composite material, the composite material is altered so it can be cut by a non-optimal beam. ‘We have an applications lab dedicated to developing lasers with the engineering teams. We look at the wavelengths of these new materials. They have discrete absorption
Organic materials in car interiors can be processed with CO2
wavelengths
www.electrooptics.com
Zeljko Radojko/Shutterstock
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