We comment on the recent Letter by Cai <i>et al</i>. [Opt. Lett. <b>28</b>, 1808 (2003)] in which an approach to phase-shifting interferometry with arbitrary phase steps was proposed. Cai <i>et al</i>. based their method of phase shifting on the idea that the intensities of the reference and object beams can be measured previously, which actually makes the whole posterior phase-shifting procedure absolutely unnecessary. Their method is also based on the statement that the phase of the Fresnel diffraction pattern of a test object if generally a spatially random distribution, which in most situations is wrong.
© 2004 Optical Society of America
José A. Ferrari and Eugenio Garbusi, "Comment on 'Phase-shift extraction and wave-front reconstruction in phase-shifting interferometry with arbitrary phase steps'," Opt. Lett. 29, 1257-1258 (2004)