Photothermal deflection microscopy of dielectric thin films

A system has been developed which employs the photothermal deflection effect to map the absorption characteristics of thin‐film optical coatings used in high‐energy laser applications. The high spatial resolution, low‐level absorption data provided by this system may reveal flaws which could become damage sites when exposed to high‐energy laser radiation. Qualitative data of mappings of areas of the coating in which defects were found which were not observed with Nomarski microscopy are presented. Measurements are in progress to ascertain correlations between the absorption sites and laser induced damage.