Impact of outgassing organic contamination on laser-induced damage threshold of optics: effect of laser conditioning

In the midst of the Mega Joule Laser project, a study of the impact of organic contamination on optical surfaces has been launched. Last year, we presented results on intentionally contaminated optics by outgassing products of a typical material of the LIL (Ligne d'Integration Laser, the prototype laser line of the future LMJ). A small quantity of organic contamination deposited on high reflective mirrors decreased their R/1 laser induced damage threshold. As the LIDT R/1 test procedure may "condition" the optical component, further raster scan tests have been implemented on new intentionally contaminated samples to assess the test procedure impact on the LIDT results for different contaminations. The aim of this work is double: -First, the impact of organic contamination deposited on optical surfaces by outgassing will be evaluated by laser induced damage threshold measurement, after a laser shot at nominal fluence ; -The second objective is to evaluate the real effects of "conditioning", notably towards organic contamination deposited on optics.

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