A number of interesting and useful interferometric measurements can be obtained by using more than one wavelength. The following report discusses how holography enhances both the possibilities and results obtained from multiple-wavelength interferometry. A discussion of approaches is followed by a number of examples from our own laboratory work in this area. In the first example, two widely separated wavelengths are employed to exploit the dispersive properties of a solution to measure temperature and concentration simultaneously. In this case holographic recording makes phase-shifting interferometry possible with a snapshot recording. In the second example, the use of anomalous dispersion at the resonance of a gas is exploited to measure species concentration. This is accomplished by direct optical subtraction of the two different wavefronts, one at resonance and the other off resonance. Finally, two closely spaced wavelengths are reflected from a diffuse surface and subtracted optically by holography to contour a surface.
David C. Weber, Neal J. Brock, James D. Trolinger, James E. Millerd, "Multiple-Wavelength Holographic Interferometry" in Journal of Imaging Science and Technology, 1997, pp 342 - 354, https://doi.org/10.2352/J.ImagingSci.Technol.1997.41.4.art00006