Study of Laser-Irradiated Thin Films
Abstract
Laser-induced structural damage to dielectric thin-film coatings was investigated using a TEM(00) Q-switched ruby laser. This study included mono-, bi-, and multi-layered coatings of the materials TiO2, SiO2, ZrO2, MgF2, and ZnS on substrates of glass, fused silica, rocksalt and spinel. The samples included coatings for antireflection and reflection at the ruby wavelength and were produced either at USC or by a commercial vendor. Damage threshold energy densities were measured with attention paid to dependences on laser beam spot- size, film material and thickness, substrate condition and incipient scattering of the film. Two major facts about laser damage to thin films were discovered. One fact is that laser-induced scatter, indicative of film break-up, is observed prior to the threshold of spark formation at the film. The other fact is that the damage threshold of the thin-film increases as the laser beam spot- size decreases. A theoretical model was developed which correlated the nature and distribution of coating defects to this spot-size dependence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1973
- Accession Number
- AD0774022
Entities
People
- Brian E. Newman
- Kang M. Leung
- Larry G. Deshazer
- Nabil Alyassini
Organizations
- University of Southern California