19 February 2018 Beam shaping and in-situ diagnostics for development of transparent materials processing
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Several applications based on laser machining of transparent materials by nonlinear induced absorption of ultra short pulses are meanwhile well established. We apply in-situ diagnostics for the development auf new and improved processing techniques. The novel pump-probe system offers flexible pulse duration, burst options, beam shaping and repetition rates up to 2 MHz at an extended range of probe delay. This allows a deep inside into the spatial and temporal characteristics of nonlinear absorption and subsequent relaxation. By including effects of incubation and accumulation, mechanisms on multiple temporal and spatial scales can be addressed.

This is exemplified by results achieved for ablation, welding and modification cutting by elongated beam shapes. At a probe delay in the ns-range, pressure waves can be observed. Applying fluence near threshold, a remarkable influence of accumulation on the absorption becomes obvious even at repetition rates down to 10 kHz. Increasing the repetition rate results in thermal load on a zone by far extending the initial absorption region, as can be seen by pump-probe polarization microscopy. Pump-probe diagnostics support aberration correction for improved modification cutting by Bessel-like beams. The examples on processing results highlight the achievements enabled by thorough consideration of the plurality of relevant effects.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. Kumkar, M. Kumkar, F. Zimmermann, F. Zimmermann, J. Kleiner, J. Kleiner, D. Flamm, D. Flamm, M. Jenne, M. Jenne, D. Grossmann, D. Grossmann, S. Nolte, S. Nolte, } "Beam shaping and in-situ diagnostics for development of transparent materials processing", Proc. SPIE 10522, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVIII, 105220H (19 February 2018); doi: 10.1117/12.2300733; https://doi.org/10.1117/12.2300733

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