High energy laser windows

Progress has continued toward the goal of understanding and diminishing absorption and increasing strength and toughness of alkali halides for laser windows. The emphasis has continued to center on KCl as a viable candidate and a model for other halides, but work to transfer KCl technology to KBr has begun. Discussed is research on: press forged KCl--microstructure development and mechanical and optical properties; summary of 10.6 micron laser testing of uncoated KCl; multiphonon absorption in ionic crystals; multiphonon absorption studies; growth, surface finishing and optical characterization of sodium fluoride and other fluoride laser window crystals; spectral emittance of fluoride laser window crystals; new instrumentation; and fracture analysis of ZnSe.