| 摘要 |
<P>PROBLEM TO BE SOLVED: To highly accurately measure a scanning quantity of an aspherical face to be inspected without using reflected rays of light in the neighborhood of a vertex of the aspherical face to be inspected in aspherical face measurement by a scanning type interferometer. <P>SOLUTION: Step scan is performed on a face to be inspected in multiple stages, and a phase corresponding to a shape measurement area of an interference stripe acquired by image pickup means and a wavelength of light measured by a wavelength measurement unit are respectively measured for the every step scan. Afterwards, a distance between an arbitrary point M on the face to be inspected and a center of curvature O of a reference spherical face is defined as a function of a wave number (integer) including the measured phase and wavelength as parameters, and the wave number in the each step is calculated from the relationship of the functions between the adjacent steps, so as to calculate moving amounts between the respective steps. Furthermore, a measurement value of the distance between the point M on the face to be inspected and the center of curvature O of the reference spherical face is calculated from the wave number and its function, and a design value of the distance between the point M and the center of curvature O is calculated by using the calculated moving amounts, in order to calculate a shape error of the face to be inspected from a difference between the measurement value and the design value. <P>COPYRIGHT: (C)2012,JPO&INPIT |
