Ultrashort pulsed laser micromachining of glass using an interlaced laser beam scanning methodWednesday (24.06.2020) 16:30 - 16:50 Room 3
Modern industrial high average power ultrashort pulsed lasers are capable of producing femtosecond and/or picosecond pulses with very high pulse repetition frequencies (PRFs), even in the MHz range, with pulse energies high enough to machine metals and glass. This suggests that such lasers should provide high process throughput. Unfortunately, laser machining at very high PRFs does not always lead to improved process throughput because laser-induced heat in a workpiece often causes its overheating, uncontrolled melting, oxidation, bending or even cracking. The simplest method to avoid these unwanted effects is to reduce the PRF and the laser beam scanning speed, but of course this also reduces process throughput and overall efficiency. A partial solution is to equip a laser system with a high-speed laser beam scanning unit that allows the laser beam to move with a high speed, thereby maintaining appropriate pulse overlap at an increased PRF. Another solution is to split the output laser beam into an array of less powerful beamlets by using, for instance, a diffractive optical element. This method enables processing of multiple areas on the workpiece simultaneously.
In this paper, we present a very simple method that increases process throughput without modifying the laser machining system. By changing only the laser beam scanning strategy, from "sequential" to so-called "interlaced", we were able to almost double the removal rate of borosilicate (Borofloat®33) glass. The effect of this easily-implemented change on process throughput and machining quality will be presented for different PRF values and pulse overlaps, two pulse durations and two laser wavelengths. In this work, we also used a high-speed camera to record the picosecond laser micro-machining of glass for both the sequential and interlaced scanning methods. The videos helped us to understand the mechanisms that lead to the machining improvement demonstrated with the interlaced approach.
This work is part of the MILEPOST project (Grant agreement no.: 695070), which received funding from the European Research Council (ERC) under the European Union Horizon 2020 Research and Innovation programme. This paper reflects only the authors’ view and ERC is not responsible for any use that may be made of the information it contains.
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