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18 June 2002 Onset of laser ablation in CaF2 crystal under excimer laser irradiation
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Proceedings Volume 4637, Photon Processing in Microelectronics and Photonics; (2002) https://doi.org/10.1117/12.470624
Event: High-Power Lasers and Applications, 2002, San Jose, California, United States
Abstract
With the widespread application of excimer lasers for micro- processing, optically transparent materials in the UV region have become more important as optical components. The transparent materials currently available commercially are silica glass and fluoride crystals, CaF2 and MgF2. The resistance of these materials against cumulative irradiation of excimer lasers is required from the viewpoint of application, and it is important to clarify the mechanisms of the optical damage on these materials. In this paper, we report the onset of laser ablation, that is, the initiation of optical breakdown and plume formation, in CaF2 crystal under cumulative irradiation of an ArF excimer laser. When the laser fluence is below the ablation threshold, a blue luminescence due to self-trapped exciton is observed from the whole laser-irradiated region. When the fluence ins increased near the threshold, successive irradiation finally cause a bright, localized luminescence due to the initiation of laser ablation. SEM images of the laser-damaged region show two features: (1) a small bump with pits of the order of 0.1 micrometers formed by UV laser absorption and following local heating, (2) small cracks with triangular fragments caused by mechanisms stress under local heating.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yoshizo Kawaguchi, Aiko Narazaki, Tadatake Sato, Hiroyuki Niino, and Akira Yabe "Onset of laser ablation in CaF2 crystal under excimer laser irradiation", Proc. SPIE 4637, Photon Processing in Microelectronics and Photonics, (18 June 2002); https://doi.org/10.1117/12.470624
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