248NM LASER INTERACTION STUDIES ON LAF3 MGF2 OPTICAL COATINGS BY CROSS-SECTIONAL TRANSMISSION ELECTRON-MICROSCOPY/

LaF3/MgF2 high-reflectance optical multilayer coatings were investigat ed by cross-sectional transmission electron microscopy (XTEM) concentr ating on the evolution of the film structure during growth and due to laser irradiation. The irradiated samples show: enhanced texture compa red to the as deposited films, indicating , that grain growth took pla ce due to the laser irradiation. The waviness of the interfaces betwee n the single quarter-wave layers in the multilayer system increases wi th increasing distance from the substrate. This effect may result ill increased scatter losses. especially in the ultraviolet spectral regio n. (C) 1998 Elsevier Science S.A.