Role of coating defects in laser-induced damage to dielectric thin films

The laser-induced damage thresholds of two different dielectric thin-film coatings increased with decreasing spot size and were invariant for spot sizes greater than 150 μm. A simple model has been suggested that the distribution and nature of coating defects have played an important role in this spot-size dependence, e.g., the probability of the laser beam striking a defect site will be greater for larger spot sizes and that damage in materials can be distinguished as defect damage and intrinsic damage.