Even senior engineers learn from Opto-Mechanical System Design course
Next year, March, 15-17, the three-day Opto-Mechanical System Design course will be given once again in Eindhoven (NL). The DSPE initiative targets mechanical, mechatronic and optical engineers, offering a broad overview of this omnipresent and ever-more relevant multidiscipline.
It contains numerous design examples, embedded within a structured approach, that illustrate the tricks of the trade in opto-mechanical system design, which increasingly impacts the overall performance of high-tech systems. One of the objectives of the course is to help engineers from the various disciplines develop a common opto-mechanical language.
This year’s edition, last March, was attended by no less than seven engineers from Raith Laser Systems in Eindhoven. The company designs and builds direct-write laser systems that create patterns on substrates such as wafers or glass. Direct writing is a slow but very flexible lithographic process that is directly digitally controlled without the use of a mask that would allow only one pattern to be created. Raith’s systems use laser diodes with a wavelength of 375 or 405 nm and a resolution down to 200 nm. Applications include photonics (structures for light coupling), sensors (gratings), lab-on-a-chip/microfluidics (micro-channels), and holography (interferometric patterns).
Among the course attendants from Raith was senior development engineer Jan Aarts. “It felt like a company outing,” he says with a laugh. “There were two mechatronic engineers, me included, and two optical engineers, who all work on optomechanical system design on a daily basis, and three engineers who are indirectly involved. It was very useful for each of us.” Aarts studied mechanical engineering at TU Eindhoven and subsequently joined Philips Research. There, he already started working on optomechanical system design, as he was involved in pioneering the Blu-ray technology, the successor to the DVD.
He then worked in this field at various companies until, at 4PICO, CD/DVD/Blu-ray production machine building came to an end and direct laser writing popped up as an alternative business opportunity. After all, there are many similarities between the two techniques; for example, they both work with an air-bearing stage, and the Blu-ray wavelength was also 405 nm. But there are differences as well; for instance, the pattern on the round discs is written in a spiralling fashion, whereas a direct-write laser machine works with a scanning x-y stage. In 2021, 4PICO became part of Raith, which positions itself as the global market and technology leader in maskless nanofabrication systems and characterisation solutions.
The main optomechanical challenge in direct-write system development is thermal stability, Aarts explains. “The processes we run on our machines can last for hours or sometimes even days. So, you have to take temperature variations into account to be able to keep the laser spot targeted precisely at the right position. To achieve that as well as possible, you have to make smart material choices, make the construction symmetrical (to create a temperature-insensitive thermal centre, ed.), and employ more such tricks. These were all addressed in the course.”
Aarts speaks highly of the course teachers. “They could explain it beautifully and were very practical. It didn’t get stuck in theory, absolutely not. Their examples came mainly from astronomy and space. Vacuum is very important there, but you also have to deal with extreme temperature variations, so thermally stable design is all the more important.” One of the teachers was Gabby Kroes, senior opto-mechanical system engineer at SRON (Netherlands Institute for Space Research). “She works on space applications; their papers are public, so I can learn from their design solutions.”
Aarts has to dive deeper into design for thermal stability, because the challenges at Raith are growing. “We are moving to increasingly lower nanometer levels and have been building increasingly larger systems lately. If you make everything ten times bigger, many things are suddenly no longer that trivial and you have a ten times bigger problem. In the course, I learned once again how to handle all these issues. Although I have been in the field for thirty years, I still gained new ideas. It was also nice
meeting people from other companies. Yes, the course was educational for our less experienced engineers, but also for a senior engineer like me.”
www.raith.com
