SEDL / STP / STP1028-EB / STP18585S

Photon Induced Desorption and Emission from Thin Film Dielectric Surfaces

Kardach, JA
Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico

Stewart, AF
Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico

Guenther, AH
Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico

McIver, JK
Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico

Pages: 17    Published: Jan 1988

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Abstract

Results from 1-on-1 and N-on-1 laser induced damage experiments, together with associated charged particle emission from 22 dielectric thin films on fused silica, sapphire, and calcium fluoride substrates are reported. A Q-switched Nd:YAG laser (1.06 microns, 5 nsec (FWHM), 500 microns 1/e² diameter) was used to irradiate the half wave (at 1.06 microns) thin films. The experiments were performed in a UHV vacuum chamber with a base pressure of 10^-8 Torr, and were computer controlled.

Preliminary analysis indicates that the damage threshold for dielectric thin films increases with the substrates thermal conductivity, even for these very short laser pulses. Laser damage thresholds and charge emission curves are presented and characterized as a function of the incident laser energy density.