| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for absolutely calibrating a tested surface (spherical surface) by obtaining measured interference data of the surface in a vertically erected state. SOLUTION: A first set of absolute calibration data on the reflection characteristics of a reflecting mirror 14 is obtained from a first set of measured interference data obtained by changing a plurality of times the relative position between a Fizeau's surface 11a and the tested surface 13a and from a second set of measured interference data obtained by using the mirror 14 while keeping constant the relative position between the surface 11a and the surface 13a (process 1). A second set of absolute calibration data of an interference optical system is obtained by disposing a Fizeau's surface 12a (reference surface) so that the reflection characteristics of the mirror 14 are applicable between the surface 12a and the surface 13a (process 2). A third set of measured interference data is obtained by disposing the surface 12a and the surface 13a so that the reflection characteristics are applicable. Absolute calibration data for the sphericity of the surface 13a is obtained from the third set of measured interference data and the first and second sets of absolute calibration data (process 3).
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