<title>Absorption calorimetry and laser-induced damage threshold measurements of antireflective-coated ZnSe and metal mirrors at 10.6 μm</title>

Abstract

Absorption and pulsed laser induced damage of antireflective coatings on ZnSe and high reflecting metal mirrors were studied. As deposition materials for the AR-coatings germanium zinc sulfide zinc selenide cadmium selenide and different fluorides were selected. For protecting and enhancing of metal mirrors zinc sulfide and zinc selenide were used in conjunction with ThF4 as low index material. The films were deposited by thermal evaporation. Absorption measurements were performed with the aid of a laser calorimeter and a cw C2aser Single-shot and multiple-shot (prf 3 Hz) damage thresholds were measured by a computer controlled test facility using 100 ns pulses from a TEA C02-laser. The gaussian beam was focussed down to a diameter of 1. 4 mm on the sample surface. A scatter measurement system and an on-line video microscope were applied for damage detection. Damage morphology was investigated by Nomarski- and scanning electron microscopy. Key words: C02-laser laser induced damage single-shot multiple-shot laser calorimetry photothennal deflection spectroscopy ar-coating metal mirror video image processing. 1.