Interferometric laser profilometer for rough surfaces.
A simple synthetic-wavelength interferometer is reported that uses two wavelengths of a multimode laser diode. The difference in interferometric phase measurements at the two wavelengths provides absolute range information to an accuracy of 0.75 microm over an ambiguity interval of 310 microm. The instrument can be used to profile surfaces too rough to be measured by conventional interferometry.
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de Groot