MULTIPLICATIVE MOIRE 2-BEAM PHASE-STEPPING AND FOURIER-TRANSFORM METHODS FOR THE EVALUATION OF MULTIPLE-BEAM FIZEAU PATTERNS - A COMPARISON

A phase-evaluation method of multiple-beam Fizeau patterns that combin es two-beam phase-stepping algorithms with the moire effect was previo usly reported [Appl. Opt. 34, 3639-3643 (1995)]. The method is based o n a multiplicative moire image-formation process obtained by the direc t superposition of high-frequency multiple-beam Fizeau carrier fringes upon a transmission grating (working as a phase modulator). We presen t a comparison between this multiplicative moire two-beam phase-steppi ng method and the well-known Fourier-transform method for the topograp hic measurement of an undoped The discrepancy between the two methods yields a rms phase-difference value of the order of (similar to 2 pi/9 0). (C) 1998 Optical Society of America.