An accurate, repeatable, and well characterized measurement of laser damage density of optical materials.

Known for more than 40years, laser damage phenomena have not been measured reproducibly up to now. Laser resistance of optical components is decreased by the presence of material defects, the distribution of which can initiate a distribution of damage sites. A raster scan test procedure has been used for several years in order to determine laser damage density of large aperture UV fused silica optics. This procedure was improved in terms of accuracy and repeatability. We describe the equipment, test procedure, and data analysis to perform this damage test of large aperture optics with small beams. The originality of the refined procedure is that a shot to shot correlation is performed between the damage occurrence and the corresponding fluence by recording beam parameters of hundreds of thousands of shots during the test at 10Hz. We characterize the distribution of damaging defects by the fluence at which they cause damage. Because tests are realized with small Gaussian beams (about 1mm at 1∕e), beam over...