FEATURE BEAM ANALYSIS
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periods of time, to understand how that laser performs over its entire lifetime, and how laser power changes between R&D application and production, and how that laser is changing over its production life.” There are also challenges from the
production environment and from the thermal effects of the laser system. The debris that comes off a process can often be harmful to the products that are taking the measurements. For example, if there’s a protective window on the system to protect the laser from process debris, contamination on the window will absorb some of the laser light. McCauley comments: “If you have a flat mirror, when heat is added to that mirror you get a lensing effect; that window that’s supposed to be 100% transmissive is now acting like a lens in changing the properties of that laser. Our measurement devices help the laser user understand whether they have some kind of change in the property of the laser and, if they do, how to try and minimise that as much as possible by performing maintenance on your laser system. These thermal effects cause the laser power density to change, and therefore the overall process changes.” McCauley says that Ophir has been
working on making products more friendly to harsh production environments. “We’ve been engineering products that are more practical to design and integrate into a system,” he says, rather than having a standalone measurement device. Ophir has released four new products
recently: the Industrial Power Meter, a high laser-power measurement device that’s designed to be integrated into a system and left for long periods of time; BeamWatch Integrated, a combined laser beam profiler and laser power measurement device that’s designed to be integrated into a system; BeamWatch AM, specifically for measuring laser beam profile and laser power simultaneously in additive manufacturing systems; and BeamPeek, which is an all-in-one beam profiler and laser power measurement device. There are also additional challenges
that come from trying to measure very high energy density and very rapid lasers, as Prefontaine notes: “The power density that’s used to cut the metal can also be used to cut our own apparatus, and so making stronger absorbers or dealing better with the power and heat that’s generated by these utilities is a big problem.”
The holy grail of laser measurement While there have been significant advances in beam analysis, there are nonetheless limitations and compromises that still have to be made in the measurements. There
26 Electro Optics November 2022
Laser beam measurement from Gentec Electro-Optics
are two approaches to measuring a laser beam: working in-process, where you measure a laser’s performance in real time as the process happens; and an at-process measurement, where you measure where the process happens, but it’s between parts. McCauley gives the pros and cons of each: “The in-process measurement is more of a real-time feedback as the process is happening, but the drawback is that in most cases it only measures part of the laser system. You cannot really take a measurement of the process while the process is happening, so it will paint an incomplete picture of how that laser is performing during the process. With at- process measurements you are capturing all
‘The holy grail of laser measurement is to be able to measure the performance of the entire laser during the process to feed that back to the system’
of the laser characteristics at the process, but the drawback is it has to be done offline. It takes away from production time in order to collect those bits of information on the system.” McCauley says the holy grail of laser measurement is to be able to measure the performance of the entire laser during the process in order to feed that back to the system. “That’s something that is certainly on our mind,” he says. “It’s something we’re considering when we develop our products, but that’s still one of the challenges that really needs to be overcome. Eventually we can come up – or somebody will come up – with a system that can accomplish this. We’re getting very close.”
Growing importance While industry has not always been as enthusiastic as it could have been in the adoption of the latest beam analysis technology, there is an inevitability to its growing importance. As McCauley puts it: “Between five and 10 years ago this was information that was ‘nice to know’. It was nice to know what your power was doing during a process, it was interesting data to some people, but with the drive of industry 4.0, the internet of things, it’s becoming more of a requirement. In some markets, for instance medical device manufacturing, it is a requirement, and it’s even moving towards requiring a beam profile to see what the laser is doing at the process.” A similar point was made by Prefontaine: “Laser parameter measurement and control will become more demanding as quality and throughput have to increase, but also a lot of these parameters will be required… as industry standards become normalised, as is happening right now in additive manufacturing. Laser parameters are required to be mentioned to produce certain classes of parts, and these standards will only become more strict in the future.” While beam analysis will increasingly become a requirement in some areas of additive manufacturing, there is also the possibility for new unexpected and innovative applications. An example Prefontaine provides was the impact of beam analysis on anti-counterfeiting: “It’s a little bit like cryptography where the various laser parameters produce a certain result, but from that result it’s difficult to know what the laser parameters were. Very tightly controlling different laser parameters can result in a unique marking, which can be part of an anti-counterfeiting scheme.” As beam analysis begins to play an
important part in existing applications, more innovative applications are sure to emerge in the future. EO
@electrooptics |
www.electrooptics.com
Gentec Electro-Optics
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