SEDL / STP / STP689-EB / STP39108S

CW Laser Damage in AR Coated Alkaline Earth Fluorides at 3.8 µm

Detrio, JA
University of Dayton Research Institute, Dayton, Ohio

Petty, RD
University of Dayton Research Institute, Dayton, Ohio

Pages: 8    Published: Jan 1979

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Abstract

We have measured the damage threshold of AR coated SrF² and oriented single crystals of CaF² using a CW chemical laser operating at approximately 3.8 m. The samples were irradiated for three seconds up to a total power of 8.4 kW. The specimens all failed at a power density of 22 kW/cm² over a 0.3 cm² area. The failure mode was not catastrophic and is believed to consist of plastic deformation due to compressive loading in the center of the irradiated region on the exit surface. The surface absorption is the dominant contributor to the failures. A novel statistical approach to defining the damage threshold and assessing the confidence level of the data was used.