Abstract

Experiments and analysis indicate that graded random phase modulation can be used to apodize a laser beam. In the case of an obscuration or a hard edge it can prevent the formation of Fresnel-diffraction ripples. For example, here the interaction of a 1-μm-wavelength laser beam with a central obscuration of half-width a = 100 μm is studied theoretically. It is found that if the exit surface of a window, placed immediately downstream of the obstacle, is randomly modulated with a Gaussian amplitude transverse correlation length l = 50 μm and a mean-square amplitude that decreases exponentially from a peak height of ~1 μm² away from the center of the obscuration with transverse scale length L = 500 μm, then the Fresnel-diffraction ripples normally produced by the obscuration are eliminated. The scaling of these results is also discussed. The calculations are in general agreement with experimental results.

© 1986 Optical Society of America

Theory of laser beam apodization with a graded random phase window

Roger A. Haas
Appl. Opt. 27(13) 2708-2718 (1988)

Role of intensity fluctuations in laser-beam apodization with a graded random phase window

Roger A. Haas
Opt. Lett. 13(11) 943-945 (1988)

Laser-beam apodization with a graded random phase window: erratum

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Opt. Lett. 12(3) 223-223 (1987)

Coherent summation of laser beams using binary phase gratings

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Variable intracavity spectral windowing in a synchronously pumped femtosecond cw dye laser

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