Accession Number : ADA019325

Title :   The Effects of Surface Structural Properties on Laser-Induced Damage at 1.06 Micrometers.

Descriptive Note : Final rept. 1973-1975,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : House,Richard A. , II

Report Date : 12 DEC 1975

Pagination or Media Count : 156

Abstract : Short-pulse, laser-induced breakdown has been correlated with several surface properties and preparation techniques, for five transparent dielectric materials: Fused Silica, BK-7, ED-2, ED-4, and Cervit. The laser parameters were: 1.06 micrometers wavelength, 40 ns pulse width, TEM sub 00 mode, and 147 micrometer spot size. Damage threshold correlated strongly with RMS surface roughness, and measurements of roughness can be used to predict the threshold. Threshold was not affected by grinding procedure. Surfaces overcoated with thin dielectric films had reduced thresholds. Flame-polished and ion-polished surfaces had greatly increased thresholds. Surface contamination by rouge polishing compound caused a drastic threshold reduction at a wavelength of 1.06 micrometers. Nitric acid etching increased damage threshold. Ultrasonic cleaning could increase surface roughness and reduce threshold. The technique of roughness-normalization facilitates the comparison of various surface preparation techniques.

Descriptors :   *Infrared lasers, *Radiation effects, *Surface properties, Silicon dioxide, Surface finishing, Thin films, Ultrasonic cleaning, Etching, Theses, Dielectrics

Subject Categories : Lasers and Masers
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE