2001 Fiscal Year Final Research Report Summary
Study of Pulsed-Laser Drilling Process Using Transparent Materials: Time-Resolved Observation in Drilled Holes
| Project/Area Number |
11650736
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
ITO Yoshiro Nagaoka University of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (60176378)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Susumu Nagaoka College of Technology, Department of Electric Engineering, Associate Professor, 電気科, 助教授 (10217854)
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| Project Period (FY) |
1999 – 2000
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| Keywords | laser / ablation / surface phenomena / transparent materials / laser machining / laser marking / time-resolved observation / imaging |
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| Research Abstract |
When we focus high power laser pulses on a surface or in 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 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 interval than 50ns, another laser was used as illuminating source. Damages occur at several points simultaneously and propagation of shock waves started from these points is clearly observed. Laser induced damages (cracks) continue to develop until some microseconds after laser pulse. Effects of pulse energy and roughness of the target surface are studied.
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