Theory of On-Axis Intensity Distribution in Thermal Lensing (LQ-10 High Power Laser Window Program).
Physical sciences research papers,
AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS
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As part of its over-all program in the identification, preparation, and application of materials for use as high-power infrared laser windows, AFCRL has investigated theoretically and experimentally the thermal lensing caused by the distortion and defocusing of a laser beam traversing a material medium. In the report, the vector Kirchhoff approximation is applied to obtain the diffraction field due to a nonuniform laser beam normally incident on an optically isotropic, annular-shaped solid lens. Detailed computations of the on-axis intensity distribution versus time in both abstract and real variables are presented for Gaussian beams incident on various transmitting materials at 10.6 micrometers. The results of the computations demonstrate the role played by induced thermal stresses, incident beam shape, refocused beam, center-chopped beam, the the mating of two compensating materials. Two rough figures of merit are given for rating any windows optical and mechanical-optical performance. It is shown how lensing depends on material parameters. Author
- Lasers and Masers