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Proceedings Paper

Fresnel Ripple Mapping Of Water-Cooled Laser Mirrors
Author(s): Charles L. Budde
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Paper Abstract

It is well known that diffraction in an optical train will produce near-field Fresnel intensity ripples. A previous paper by Avizonis, O'Neil , and Hedin hypothesized that these Fresnel ripples would be mapped by typical water cooled laser mirrors producing surface distortions, which in turn would cause a drop in peak far-field intensity. This Fresnel ripple mapping phenomenon was studied by developing a detailed finite element model of a one inch by one inch segment of a water cooled laser mirror. The model was loaded with a uniform surface heat flux with various orientations of Fresnel intensity ripples superimposed upon it. A nonlinear steady-state heat transfer analysis was per-formed to determine the temperature distribution within the model. A thermal deformation analysis was then performed and the mirror surface distortion was computed. All analyses were performed using the NASTRAN finite element computer code. The results showed that the mirror indeed mapped the Fresnel intensity ripples. The mapping effect was shown to be insignificant for the particular cases analyzed, but projected results indicated that the Fresnel ripple mapping phenomenon could be significant for higher power and/or shorter wavelength laser systems.

Paper Details

Date Published: 30 December 1981
PDF: 6 pages
Proc. SPIE 0293, Wavefront Distortions in Power Optics, (30 December 1981); doi: 10.1117/12.932331
Show Author Affiliations
Charles L. Budde, Air Force Weapons Laboratory AFWL/ARLB (United States)

Published in SPIE Proceedings Vol. 0293:
Wavefront Distortions in Power Optics
Claude A. Klein, Editor(s)

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