BEAM DELIVERY PULSE FINGER ON THE
Can beam focusing and scanning systems keep pace with new laser technologies such as ultrashort pulsed lasers, asks Beth Harlen
W
hen considering laser processing productivity, one aspect that needs to be addressed is how the beam is delivered to the workpiece.
Scanning technologies are a big part of this and have largely developed alongside the lasers they work with. Indeed, as Georg Hofner, CEO of Scanlab, pointed out, some sectors, such as selective laser melting (SLM) and additive manufacturing owe their very existence to scanning technology. At its heart, a laser scanner
needed for key technology deployment.’ He added that the demand for scanning
deflects and positions the beam on the workpiece for precision welding, cutting, and marking. Typically, this involves highly dynamic rotary drive moving mirrors – as found in galvanometer (galvo) scanners. ‘Because scan systems turn lasers into tools, the focus is always on intended applications and workpieces to be processed, whereby production speed and precision are oſten the crucial application factors,’ explained Hofner. ‘But galvos with ultra-low moving masses had first to be developed to achieve the high processing speeds and maximum precision
26 LASER SYSTEMS EUROPE ISSUE 29 • WINTER 2015
establish a fast scanning device that can really harness the potential of [USP] lasers?
How do you
systems is driven by growth in laser processing markets. Sales of ultrashort pulse (USP) lasers for industrial processing have increased rapidly over recent years, because of the potential that comes with having pulse lengths in the range of around 10 picoseconds to 100 femtoseconds. With a high peak power intensity, fast repetition rate and broad spectrum, these lasers are ideally suited to applications where precision and cost- efficiency are paramount. Micromachining is one such application, as the lack of heat diffusion from USP lasers ensures there is no collateral damage to the surrounding surface. Tis and other attributes have led to demand for the technology in sectors ranging from automotive and electronics, to medical. Hofner commented that for
years the industry has been filled with discussions surrounding the many different applications that could benefit from USP lasers, but that the talk oſten outweighed the reality. Now, he said, the situation is changing and the
technology is becoming more prevalent. But the question for companies like Scanlab remains: how do you establish a fast scanning device that can really harness the potential of those lasers? ‘Tis question is why we always work closely with the industry to try to understand, as much as possible, the demands that they have,’ said Hofner.
Delicate balance Hofner likens the challenge of developing a scanning device capable of keeping up with ultrashort pulsed lasers to that of designing a motorsport car. Scanning manufacturers need to be able to move the laser’s clearly defined focus spot very quickly, precisely and at a high dynamic. Te laser power must be maintained and transferred down to the workpiece, but if the mirror were to have any imperfections, such as polarisation, the wavefront would be distorted. So, going back to the car metaphor, a racing car needs a stiff chassis so the vehicle doesn’t fly out of the corners, a powerful motor
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