Comment: absolute measurement of roughness and lateral-correlation length of random surfaces by use of the simplified model of image-speckle contrast.
This comment demonstrates several errors in the derivation of speckle contrast and corresponding measurements reported by Cheng et at. (Appl. Opt. 41, 4148 (2002)] for a 4f optical system. In particular, the theoretical derivation is wrong: It is used outside of its domain of validity, and the experimental results do not support the theoretical analysis.
Yura
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Electronics and Photonics Laboratory, The Aerospace Corporation, P.O. Box 92957, Los Angles, California, USA.
Hanson
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