Product Code: ICA13_M202

Parallel Femtosecond Laser Processing using Intensity Modulated Diffraction Pattern Produced with Spatial Light Modulator
Authors:
Jarno Kaakkunen, VTT Technical Research Centre of Finland; Lappeenranta Finland
Martti Silvennoinen, University of Eastern Finland, Department of Physics and Mathematics; Joensuu Finland
Kimmo Paivasaari, University of Eastern Finland, Department of Physics and Mathematics; Joensuu Finland
Petri Laakso, VTT Technical Research Centre of Finland; Lappeenranta Finland
Pasi Vahimaa, University of Eastern Finland, Department of Physics and Mathematics; Joensuu Finland
Presented at ICALEO 2013

Due to technical development of the adaptive optics, use of them in various laser processing applications has begun possible. These techniques based on the adaptive optics have been applied with various lasers to generate diffraction patterns with equal intensity spots. In this paper ultrashort laser pulse ablation with amplitude modulated diffraction pattern is presented. Diffraction patterns are generated with Computer Generated Holograms (CGH) created using Spatial Light Modulator (SLM). Applied CGHs are designed using multiplexed phase Fresnel lens and optimized using Iterative Fourier Transform Algorithm (IFTA) based method. With this kind of designing procedure it is possible to generate diffraction patterns with intensity variation between diffracted spots. By intensity modulating the diffracted beams it is possible to laser ablate virtually arbitrary patterns with depth variation into the different materials. In this paper different kinds of CGHs are designed to generate various diffraction patterns with intensity modulation. These patterns are used to ablate grey level images directly into the silicon using ultrashort pulses.