| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure eccentricity without being influenced by a surface shape by irradiating two coherent beams of light in the converged intersecting manner near an apparent center-of-curvature position, and measuring the center-of-curvature position of a spherical surface of a measured diameter to a reference axis from the fluctuation of interference fringes formed by super posing both beams reflected from the measured diameter. SOLUTION: A measured optical system is rotated around a rotation axis 44, and interference fringes formed by superposition fluctuate if a spherical surface 5 corresponding to a measured diameter 4 is eccentric. Out of the interference fringes detected by a photo detecting means 33, only the components synchronous with the rotating cycle of a rotation holding means 41 detected by a rotation angle detecting means 43 are extracted by an arithmetic means 45 to measure the eccentric quantity and eccentric bearing of the center of curvature 6 of the spherical surface 5 to the rotation axis 44. In the same way, eccentricity is successively measured on a plurality of different diameters of the a spherical surface, considering the a spherical surface to be spherical surface near each diameter, and a center-of-curvature position corresponding to each diameter is finally determined.
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