摘要 |
An aspheric face form measuring method calculates phase information of interference light from light intensity of a fringe pattern image obtained by detecting interference light that is formed by measurement light and reference light reflected off a subject aspheric face being overlaid. The method changes a relative distance between an optical system and the subject aspheric face and transitions a position of a null region. The method performs calculation of form data for a vertical incident region where measurement light is vertically incident to the subject aspheric face, using phase information and a scanning amount. The method performs calculations of form data, of the null regions, a non-vertical incident region that is outside of the vertical incident region. The method also composites a plurality of partial form data of the subject aspheric face previously calculated, using each of a plurality of the phase information and scanning amounts.
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