A two-wavelength moire phase-shifting interferometer that uses a superimposed grating has been developed. The optical phase shifts for the two wavelengths are given by digital phase shifts of a superimposed grating displayed on a liquid-crystal spatial light modulator. A phase shift of the moire fringe is achieved by equal phase shifts with opposite signs in the two gratings. A moire phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shifts was obtained. Our experimental result shows measurements of the profile of a step object with a 2.65-µm synthetic wavelength.
© 2005 Optical Society of America
(050.5080) Diffraction and gratings : Phase shift
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.4120) Instrumentation, measurement, and metrology : Moire' techniques
(230.6120) Optical devices : Spatial light modulators
Youichi Bitou, "Two-wavelength phase-shifting interferometry with a superimposed grating displayed on an electrically addressed spatial light modulator," Appl. Opt. 44, 1577-1581 (2005)