| 摘要 |
PROBLEM TO BE SOLVED: To provide an interferometer for measuring surface shape, etc., and its measuring method which is capable of efficiently measuring the shape, etc., of not only spherical lens but also aspherical lens at high accuracy. SOLUTION: This interferometer comprises wave front forming means 6a, 8, 9 for splitting a coherent light beam from a light source 1 into a reference wave and a wave under detection and forming a wave front, corresponding to a surface 7a to be measured on the reference wave, a calculating means 12 capable of calculating surface shape and profile irregularity, based on the interference fringe pattern information taken in from photographing means 11 after superposing the reference wave and the wave under detection, and a phase control element 9, capable of modulating the phase of the reference wave irradiating the surface 7a to be measured. The calculating means 12 analyzes output data corrected, so that the null interference fringe pattern can be observed at the photographing means 11 after the phase control element 9 aligns the phase distribution of the reference wave with the surface 7a to be measured.
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