SEDL / STP / STP1141-EB / STP23638S

High Laser Damage Threshold and Low Cost Sol-Gel Coated Epoxy-Replicated Mirrors

Floch, HG
CEA Centre d'Etudes Limeil-Valenton, Villeneuve Saint Georges,

Berger, M
CEA Centre d'Etudes Limeil-Valenton, Villeneuve Saint Georges,

Novaro, M
CEA Centre d'Etudes Limeil-Valenton, Villeneuve Saint Georges,

Thomas, IM
CEA Centre d'Etudes Limeil-Valenton, Villeneuve Saint Georges,

Pages: 12    Published: Jan 1991

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Abstract

In a collaborative effort with some french industrial and university laboratories and also in contact with our colleagues from the Lawrence Livermore National Laboratory (LLNL), we have developed at Limeil-Valenton National Laboratory (LVNL) various laser-performant and inexpensive dielectric mirrors made of a resin-replicated substrate and a specific colloidal sol-gel coating. To date, we have obtained 8″ to 12″ diameter molded optical surfaces with a flatness as good as λ/10 peak to valley at 633-nm wavelength with a roughness ranging 10–15 Å RMS. We have been able to acheive coating-reflectivity exceeding 99 % using room temperature spin-coating deposition of alternate silica and alumina quarterwave layers, and conserving the original substrate flatness. Such sol-gel coated replicated mirrors averaged 13.5 J/cm² in a single shot irradiation mode and 15.1 J/cm² with a laser-annealing procedure at 1064-nm and with 3-ns pulses. The present cost of such a product is about 4–6 times cheaper than a similar component conventionally e-beam coated.