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Proceedings Paper

Dynamic observation of laser-induced damage made inside of transparent materials
Author(s): Yoshiro Ito; Satoshi Kiyoku; Tsutomu Ogura; Naotake Mohri
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Paper Abstract

When we focus high power laser pulses on a surface or inside of transparent materials, non-linear absorption of the laser radiation occurs and some laser-induced damages are introduced. This process is used in laser marking of transparent materials. We have made dynamical observations of the process by the stroboscopic imaging system which has a few nanoseconds time resolution. Output of fundamental radiation (1064nm) from a Q-switched Nd:YAG laser was focused at the surface or inside of PMMA and soda glass blocks. Second harmonic radiation (532nm) form the same laser was used as illuminating light and images were taken by a CCD camera with a band-pass filter of 532 nm. Series of images were taken at different intervals between fundamental and second harmonic light, which was controlled by optical delay line. In observation at longer intervals than 50ns, another laser was used as illuminating score. Non-linear absorption in PMMA occurs at several points simultaneously and propagation of shock waves started from these points is clearly observed. Non-linear absorptions in soda glass occurs from inside outward along the laser beam. Laser- induced damages (cracks) continue to develop until some hundreds milliseconds after laser pulse. Effects of pulse energy and roughness of the target surface were examined.

Paper Details

Date Published: 25 February 2002
PDF: 4 pages
Proc. SPIE 4426, Second International Symposium on Laser Precision Microfabrication, (25 February 2002); doi: 10.1117/12.456894
Show Author Affiliations
Yoshiro Ito, Nagaoka Univ. of Technology (Japan)
Satoshi Kiyoku, Nagaoka Univ. of Technology (Japan)
Tsutomu Ogura, Nagaoka Univ. of Technology (Japan)
Naotake Mohri, Univ. of Tokyo (Japan)


Published in SPIE Proceedings Vol. 4426:
Second International Symposium on Laser Precision Microfabrication

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