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Proceedings Paper

Influence of the contaminant size on the thermal damage of optical mirrors used in high energy laser system
Author(s): Kai Han; Rui Song; Xiaojun Xu; Zejin Liu
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Paper Abstract

The laser induced damage is a troublesome issue in the application of optical mirrors, which is related to the robustness of the whole laser system. There are two types of mechanisms about the damage of optical mirrors: thermal effect and field effect, which are responsible for the high energy continuous wave (cw) laser induced damage and the high power pulsed laser induced damage, respectively. Under the irradiation of high energy laser, the contaminant on the mirror surface absorbs the laser energy and converts the laser energy to heat. With the heat accumulating, the optical mirror is likely to fuse and even be totally destroyed. The temperature of the contaminant was measured when it was irradiated by a cw high energy laser with power intensity 3.3kW/cm2. It is found that the contaminant achieves thermal equilibrium in a few seconds and then the temperature stays at ~1700K. A physical model was established to describe the process of the thermal equilibrium. The influence of the contaminant size on the thermal damage of the optical mirror was studied theoretically. The results show that the contaminant size plays an important role in the thermal damage of the optical mirror. Only when the contaminant size is smaller than a critical size (~10μm), the contaminant may reach thermal equilibrium and the optical mirror works well in the high energy laser system. If the contaminant size is quite large (<~100μm), the optical mirror will damage under the irradiation of high energy laser.

Paper Details

Date Published: 27 September 2016
PDF: 7 pages
Proc. SPIE 9952, Systems Contamination: Prediction, Control, and Performance 2016, 99520M (27 September 2016); doi: 10.1117/12.2236773
Show Author Affiliations
Kai Han, National Univ. of Defense Technology (China)
Rui Song, National Univ. of Defense Technology (China)
Xiaojun Xu, National Univ. of Defense Technology (China)
Zejin Liu, National Univ. of Defense Technology (China)


Published in SPIE Proceedings Vol. 9952:
Systems Contamination: Prediction, Control, and Performance 2016
Joanne Egges; Carlos E. Soares; Eve M. Wooldridge, Editor(s)

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