Because the multiple-channel spatial phase shift method needs a complex pixel alignment algorithm, a special image de-warping algorithm, and a complicated adjustment structure, this method is difficult to apply as an infield measurement tool for industry. Thus, in recent years, the singlecarrier-based spatial phase shift method has become the main trend of development for new SPS-DS systems. As mentioned, both Pedrini’s Mach–Zehnder-interferometer-based SPS-DS system and B. Bhaduri’s double-aperture SPS-DS system have the weakness of a small, limited measurement area. This chapter introduces a Michelson-interferometerbased SPS-DS system that uses a single frequency carrier.
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