Towards qualification longevity of high power Space optics

Abstract

Laser systems dedicated to space missions require durable and well-characterized optics, that could ensure long-term operation under high average output power. If any of optical elements in such system experiences light-induced fatigue, the performance of whole laser system suffers. Thus, any delayed failure of the optical element would also endanger the entire space mission as repairing optic in the orbit is rather complicated. Up to now, the ability to predict optic's longevity required by space programs was difficult and expensive, because of limited experimental data and lack of validated prediction models and methods. In order to address this problem, Lidaris and ESA joined forces for a two years cooperation project ESPRESSO. The overall aim of the project is to carry out research and development work required for essential preparation of reliable longevity qualification procedure to evaluate high power laser optics with intended use in space applications. Main elements of chosen methodology for optics lifetime prediction is reported in this paper. The essence of the proposed method lies in online video detection, failure mode (damage mechanism) separation and subsequent search of appropriate extrapolation models and methods. Main experimental findings confirm the suitability of the suggested approach for prediction of laser-induced damage threshold (LIDT) from a limited set of data to the extrapolated higher number of incident laser pulses.

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“…NL740 series laser (model NL940-100-SH/TH) was successfully installed for the Laser-Induced Damage Threshold (LIDT) application [1]. The company LIDARIS used it for investigation of UV optics reliability in the joint project "ESsential PREparation Steps for Qualification Longevity of Space Optics" (ESPRESSO, PECTS call, Contract Nr.…”