Impact of contaminates on the laser damage threshold of 1ω HR coatings

Abstract

In operational laser systems, it is often difficult to keep optical components completely free of foreign material. We have investigated the performance of high damage threshold 1.053 μm high reflectors in the presence of surface contaminants. We have looked at the impact of stainless steel, aluminum, Azurlite^(R), dust, cotton fibers and polyester fibers on the performance of the mirrors under laser irradiation. The first four contaminants were deposited in sizes ranging from 30 microns to 150 microns. The fibers included lengths ranging to several millimeters. The testing was done at either a single fluence in the range of 6 J/cm² to 24 J/cm², or a ramped sequence of shots starting at 1 J/cm². We will present data showing the onset of damage, the type of damage, and the propensity to damage growth in the fluence range studied.