Product Code: ICA12_M1207

High Precision and High Throughput Surface Structuring by Synchronizing Mechanical Axes with an Ultra Short Pulsed Laser System in MOPA Arrangement
Authors:
Beat Jaeggi, Bern Univ. of Applied Science, Institute of Applied Laser, Photonics and Surface Technologies; Burgdorf Switzerland
Beat Neuenschwander, Bern Univ. of Applied Science, Institute of Applied Laser, Photonics and Surface Technologies; Burgdorf Switzerland
Urs Hunziker, Bern Univ. of Applied Science, Institute of Applied Laser, Photonics and Surface Technologies; Burgdorf Switzerland
Joseph Zuercher, Bern Univ. of Applied Science, Institute of Applied Laser, Photonics and Surface Technologies; Bleienbach Switzerland
Thomas Meier, Bern Univ. of Applied Sciences, Institute for Mechatronic Systems; Burgdorf Switzerland
Markus Zimmermann, Bern Univ. of Applied Sciences, Institute for Mechatronic Systems; Burgdorf Switzerland
Guido Hennig, Daetwyler Graphics; Bleienbach Switzerland
Presented at ICALEO 2012

High precision laser micromachining requires an exact synchronization of the laser pulse train with the mechanical axes of motion of a system to ensure for each single pulse a precise control of the position of the laser spot on the target. For Q-switched laser systems this synchronisation is normally realized by adjusting the phase of the laser pulse train in order to follow the movement of the mechanical axes. However, ultra short pulsed laser systems are almost built up in a MOPA arrangement with a passive mode locked master oscillator as seed. This implies strong limitations for the ability of realtime controlling of the phase of the laser pulse train. Due to the stable repetition rate of the laser pulses the phase of the movement of the mechanical axes must be controlled and adjusted in real time for each single spot position. This complex task requires electronic and mechanical control algorithms of the axes. We will report on our experiences with a synchronized galvo-scanner and on results of the optimization process with respect to minimum surface roughness, steepness of wall, accuracy of shape and efficiency. At high resolution screens with 3 ï­m pitch between subsequent pulses synchronization of the galvo-scanner onto the USP laser was achieved at a pulse repetition rate of 1 MHz.