The complex correlation coefficient of two fully developed speckle fields of different wavelengths is evaluated for two different geometries, and its meaning is discussed in connection with two-wavelength-measurement techniques applied to rough surfaces (e.g., two-wavelength rough-surface interferometry, two-wavelength holography, electronic speckle pattern interferometry). It is shown that in both geometries the correlation coefficient is high enough to permit meaningful measurements to be performed if the surface under test is slightly defocused, provided that the tilt of the surface normal to the optical axis of the measurement arrangement is small enough.
© 1988 Optical Society of America
U. Vry, "Calculation of complex correlation coefficients of two speckle fields of different wavelengths and their application to two-wavelength-measurement techniques," J. Opt. Soc. Am. A 5, 114-125 (1988)