The work in this thesis is a study of excimer laser induced damage in optical materials. This includes characterization of the focused laser radiation, development of sensitive techniques for the early detection of laser damage and finally laser damage studies at 193 nm and 248 nm in crystalline materials, metal mirrors and dielectric coatings. Characterization of the focused laser radiation involved pulse energy, temporal pulse profile and spatial profile measurements. This was assisted by development of a laser attenuator using a variable length liquid cell with a dynamic range of 25 dB. Non-linear absorption phenomena were observed in liquids at high intensities. Beam profiling methods were used to show the intensity distribution in the focal region of a lens was reproducible and approximated to a 2-D Gaussian function [continued]…