The suitability of sapphire for laser windows

The present paper deals with the experimental measurement of absorption coe fficients using (i) the differential dual-beam spectro-photometry method an d (ii) an intra-cavity optical loss measurement technique. The absorption c oefficient is measured experimentally in the region from the visible to the near IR. Criteria for choosing sapphire windows of optimum thickness, when they are subjected to a pressure difference of 1 atm, to avoid fracture or significant optical distortion of the laser beam are studied. Intra-cavity optical losses in such windows for Brewsterization and skew-angle inclusio ns are estimated. The study relates to various laser wavelengths, namely 33 7.1 nm, 448.0 nm, 632.8 nm, 1.15 mu m, 1.315 mu m, 2.7 mu m and 3.8 mu m.