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Proceedings Paper

Mirrors And Windows In Power Optics
Author(s): Claude A. Klein
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Paper Abstract

High-energy laser (HEL) systems involve an optical train consisting of mirrors and windows, which may compromise the system's operation because of unavoidable irradiance-mapping aberrations resulting from the absorption of some fraction of the incident laser-beam energy. This paper describes an analytic investigation of relevant processes and discusses how laser-driven mirror/window distortions may affect the performance of HEL systems with regard to focal intensities and on-target fluences. An approximate expression for the brightness at the Gaussian focus is derived on the basis of the AFWL far-field degradation model and shown to be simple enough to allow HEL system designers to assess the capability of a contemplated optical train and to evaluate its behavior as a function of beam-power level and laser run-time. Two figures of merit are introduced for the purpose of characterizing the response of power-optics mirrors and windows in terms of thermally induced wavefront errors. On using these figures of merit (FoMm and FoMw), an important result emerges: If the window-pane and the mirror-faceplate material both have positive distortion coefficients, window lensing suppresses the steady-state mirror-related phase aberration at time tc = N (D /d)2 FoMW/FoMM, where N is the number of relay mirrors and D /d is the telescope magnification. In applying these considerations to a model system operating at chemical laser wavelengths, we find that CVD-ZnSe output windows can be quite beneficial in maximizing either the peak irradiance on target or the short-pulse energy delivery capability of contemporary HEL systems.

Paper Details

Date Published: 5 August 1980
PDF: 11 pages
Proc. SPIE 0216, Optics in Adverse Environments II, (5 August 1980); doi: 10.1117/12.958463
Show Author Affiliations
Claude A. Klein, Raytheon Company (United States)

Published in SPIE Proceedings Vol. 0216:
Optics in Adverse Environments II
Mark A. Kahan, Editor(s)

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