Accession Number : AD0742244

Title :   Optical Distortion by Heated Windows in High-Power Laser Systems,

Corporate Author : RAND CORP SANTA MONICA CALIF

Personal Author(s) : Sparks,Marshall

Report Date : SEP 1971

Pagination or Media Count : 60

Abstract : The optical distortion of a laser beam by a heated window in a typical long-focal-length system can significantly reduce the beam intensity at the target at power levels less than those required to melt or fracture the window. The spatially inhomogeneous incident laser intensity causes a temperature gradient which produces nonuniform changes in the thickness and the index of refraction of the window, causing it to become a lens having aberration and birefringence in addition to a finite focal length. Expressions are derived for the thermally induced optical distortion in terms of measurable parameters such as the index of refraction, the strain-optical coefficients, and the thermal expansion coefficient. Since not all the values of these parameters are known for most materials of interest, alternative expressions are derived for use in obtaining rough estimates of the amount of distortion. (Author)

Descriptors :   (*INFRARED LASERS, INFRARED WINDOWS), (*COHERENT RADIATION, DISTORTION), (*INFRARED WINDOWS, OPTICAL PROPERTIES), INFRARED OPTICAL MATERIALS, DAMAGE, RADIATION EFFECTS, THERMAL STRESSES, THERMAL EXPANSION, POLARIZATION, TABLES(DATA)

Subject Categories : Lasers and Masers
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE