FEATURE: ULTRAFAST LASERS g
which is heading in the right direction for ultrafast applications. Our Precsys five-axis drilling system is not only able to deflect the beam in the x,y plane, but can also tilt it, enabling it to be used to drill holes which are smaller at the top, for example for parts of a car where special holes are required. This has proven to be an attractive system for many customers, and we are now seeing competitors with similar systems.’ Looking forward, Flemmer explained that galvo-based scan technology will continue to be developed further, and will be optimised close to the physical mechanical limits of the technology to reach maximum speed, precision and stability. ‘In parallel, the complexity of systems
will increase further and the integration of external peripherals is getting more and more relevant,’ he added. ‘These must not only be devices to deflect, shape or split laser beams… the integration of sensors for process analysis or process control is also an important topic. All of this is favoured by trends such as Big Data and the Internet of Things.’
Flexible integration Integrating an ultrafast laser into a system involving a moveable scan head usually requires a complex beam path of mirrors to be positioned on an articulated arm. The mirrors are placed on linear stages, enabling them to be moved towards and away from the laser source as the head is moved. While many companies use ultrafast lasers this way, the complex setup creates difficulty for machine integrators. ‘One of the hurdles to making ultrafast
lasers capable of fulfilling industrial requirements and achieving strong penetration across multiple vertical markets, is the question of whether beam delivery can be dealt with in a secured and flexible manner,’ said Fetah Benabid, founder and chief science and technology adviser of GLOphotonics. ‘The answer to this question 15 to 20 years ago, was no, and that need has become increasingly pressing over the past five years due to the
GLOphotonics’ hollow-core photonic crystal fibres enable ultrashort pulses can be transported without the need for complex mirror beam delivery paths
dramatic upscaling of average power of ultrafast laser sources.’ You might think that an optical fibre
would be a far easier and likely safer way of achieving moveable scan head technology, as is already commonplace in other areas of laser processing, however the exotic nature of ultrashort pulses prevents system integrators from being able to use standard optical fibres to deliver them to a workpiece. ‘While it is possible to use solid fibres with nanosecond lasers, putting a standard
“Integrators are now able to have an ultrafast beam that is secured nicely in a flexible hose, which can then be directed towards a workpiece”
The extremely short pulse duration of ultrafast lasers enables them to be used for precise texturing applications, as can be seen on this watch component
28 LASER SYSTEMS EUROPE AUTUMN 2019
glass fibre at the output of an ultrafast source is impractical due to glass’ low damage threshold and the dispersion and non-linearity effects that occur when the ultrashort pulses interact with the glass,’ explained Benabid. ‘The shorter the pulse, the higher the peak power gets and the more sensitive the pulse is to dispersion and the material is to pulse energy.’ However, GLOphotonics is now working with numerous integrators of ultrafast lasers because it claims to have developed a unique solution to these issues: the first fibre optic capable of delivering ultrashort laser pulses of high energy and high average power, while keeping their duration as short as possible over distances spanning tens of metres.
‘Our fibres are hollow core photonic
crystal fibres (HCPCFs), meaning the light travels through either a vacuum, through air or through another gas within their core,’ said Benabid. ‘These features lend nicely to a number of functionalities in ultrafast lasers such as beam delivery, pulse compression and frequency conversion.’ He expanded on this by explaining that the vacuum and materials incorporated in these hollow core PCFs enable the controlling of the non-linearity effects of ultrashort pulses.
This ability to use fibres to deliver
ultrashort pulses will enable a multitude of new benefits and possibilities for the integration of ultrafast lasers: ‘Integrators are now able to have a beam that is secured nicely in a flexible hose, which can then be integrated into a machine and directed towards a workpiece,’ Benabid said. ‘The use of a flexible hose will reduce the overall cost of ownership for an ultrafast laser, and in terms of engineering it will hugely simplify the design of ultrafast machines, making life much easier for system integrators.’ While Benabid has been working on
the development of low-loss HCPCFs for almost 20 years, he told Laser Systems Europe that it is only recently that the technology is in its industrialisation phase. As a result, his company is now working directly with a lot of tier one ultrafast laser manufacturers to get the technology into fully functioning laser systems and into the hands of integrators and end users. Benabid concluded: ‘From the market’s point of view, ultrafast lasers have reached a certain level of maturity. They have been demonstrated as an excellent tool for applications ranging from micromachining to surgery. Saying this, the technology is still yet to consolidate completely in terms of that maturity. One of the areas that still needs to develop further is the transporting of the ultrafast pulses, which is where GLOphotonics’ technology will come in.’ l
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