Time-resolved interferometric investigations of the KrF-laser-induced interaction zone
| Autor: | Peter Berger, Gert Callies, H. Hügel, Henrik Schittenhelm |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Free electron model
business.industry Chemistry General Physics and Astronomy Michelson interferometer Surfaces and Interfaces General Chemistry Condensed Matter Physics Laser Surfaces Coatings and Films law.invention Full width at half maximum Interferometry Optics Optical path law business Refractive index Blast wave |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0169-4332 |
| DOI: | 10.1016/s0169-4332(96)00793-3 |
| Popis: | In earlier ablation experiments the excimer laser-induced interaction zone was observed using Schlieren-photography. A spherical blast wave and, additionally, several regions separated by discontinuities behind the shock front were discovered during the pulse. This article will present experimental investigations using a Michelson interferometer in order to measure the phase front distortion of a probe laser radiation field crossing the mentioned interaction zone. The experiments were realized during the pulse (FWHM=30 ns, basis width=60 ns) under different ambient gas pressures (104–105 Pa), different energy densities (5–45 J/cm2) and with a time resolution of 500 ps. The index of refraction n was calculated using the optical path lengths obtained from the interference pattern, considering a radial symmetry. The results show a high refractive index at the shock front and a steep decrease towards the target closely behind the shock front. In this region the index of refraction tends to a lower value than the index of refraction of vacuum due to a high concentration of free electrons. A comparison with the results of Schlieren-photography gives reasonable explanations for the different regions within the interaction zone. |
| Databáze: | OpenAIRE |
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