| 摘要 |
PROBLEM TO BE SOLVED: To eliminate influence due to an error of a relative shift amount between an observed object and a reference without complicating a device structure or increasing its cost for quickly and excellently analyzing a fringe by specifying position data of at least three optional phase positions and applying predetermined computing to carrier fringe superimposed fringe image data in each phase position when fringe image data are analyzed by a phase shifting method for finding the phase of the observed object. SOLUTION: An interference fringe image having a superimposed carrier fringe and carrying shape information of the observed object is obtained in a plurality of phase shift positions while driving a phase shift element (S1). Each of the interference fringe image data is Fourier transformed (S2), and a carrier frequency (fx , fy ) is searched to find C(η-fx ,ζ-fy ) (S3). C(η-fx ,ζ-fy ) is inverse Fourier transformed (S4) for finding a relative displacement (S5), while a relative inclination is found (S6), and the respective positions are found (S7). The phase of the observed object is found by calculation using the found positions.
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