| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring device and a method for non-spherical surface shape capable of efficiently measuring many kinds of different shapes of inspected non- spherical surface. SOLUTION: The device is constituted of an interference optical system forming an interference fringe by overlapping measuring light reflected on an inspected non- spherical surface 10 on reference light reflected on a Fizeau surface as a reference surface, an arithmetic unit 18 calculating the shape of the inspected non-spherical surface based on the phase distribution of the interference fringe obtained with the interference optical system, and a pattern variable diffraction grating. The measuring light prior to introducing in the inspected non-spherical surface 10 is diffracted in the pattern diffraction grating 15, and its wave front shape is nearly agreed with the shape of the inspected non-spherical surface 10. Also, by using the relation between the grating pattern of the pattern variable diffraction grating 15 and the variation of wave front shape of the measuring light in front and back of the diffraction, the phase distribution of the interference fringe is corrected. Based on the phase distribution of the interference fringe obtained after the correction, the shape of inspected non-spherical surface 10 is obtained.
|
