Defect Characteristics Of Optical Surfaces Using Pulsed Laser Damage Methods

Laser damage to optical surfaces, particularly coated surfaces, is typically initiated by material defects that couple strongly to the laser radiation. Knowledge of damage-related defect characteristics is therefore essential to optical material development efforts and to quality control. Such characteristics include individual defect failure levels, defect densities, and content of optically absorbing impurities. Defect failure distributions containing defect density information can be inferred from properly designed laser damage measurements. The data also permit distinctions among different damage mechanisms, including non-defectrelated mechanisms involving the substrate. Inclusions containing volatile, optically absorbing impurities can be detected by mass analysis of laser-desorbed vapors. These methods are described, and examples of results are presented.