Laser-Induced Damage as a Function of Dielectric Properties at 1.06 Micrometers.
Final rept. 1973-75,
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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Ten dielectric materials in half-wave optically thick films, and eleven uncoated dielectric surfaces were subjected to damaging radiation from TEM sub 00Nd3 in a glass laser operating at 1.06 micrometers. The threshold optical electric field for damage was determined for each thin film and uncoated surface. It was demonstrated that the root mean square surface roughness was important for determining the threshold field. The basic relationship held for both the bare surfaces and for the thin films placed on surfaces with varying roughness. A theoretic-empirical formula was developed which is used to predict threshold fields as a function of material properties, such as refractive index and atomic number density, and surface roughness as well as thin-film material. The relationship holds for a variety of materials in bulk form as well as bare surfaces and thin-film coatings. Agreement between prediction and experiment was generally within twenty percent, the typical experimental accuracy. A new model of laser-induced damage was developed which accounts for material-to-material variation as well as the dependence of the damage threshold on pulse duration and spot size.
- Lasers and Masers