Irregularities in optical thickness of a given nondiffuse transparency are statistically inferred using optical heterodyne detection techniques. The modulus and phase of its complex amplitude transmittance can be recovered from a beat photocurrent by rotating the transparency in a signal laser beam. The ensemble averaged autocorrelation of the transmittance is obtained by making correlation measurements of the recovered real and imaginary parts of the transmittance. This autocorrelation function has a nonvanishing imaginary part, so that the spatial spectral profile (i.e., its power spectrum) of the transparency becomes asymmetric.
© 1978 Optical Society of America
Yoshihiro Ohtsuka and Yoh Imai, "Laser heterodyne correlation processing of optical thickness irregularities in transparencies," Appl. Opt. 17, 3402-3407 (1978)