Patent ID: 9719773
Date: 2017-08-01
CPC Classifications: G01B

Claim:
1. A method of measuring a shape of a surface of an optical element, the method comprising: a measuring step of measuring, using a measuring device, a shape for each of a plurality of regions on the surface by a surface height measurement at each of a plurality of positions in each of the plurality of regions to obtain shape data for each of the plurality of regions, each of the plurality of regions having a region overlapping another of the plurality of regions; an error obtaining step of obtaining an error of the surface height measurements for each of the plurality of regions so as to minimize a difference in shape with respect to each of the overlapping regions based on the shape data obtained in the measuring step for each of the plurality of regions; and a correcting step of correcting the shape data obtained in the measuring step for each of the plurality of regions using the error obtained in the error obtaining step for each of the plurality of regions to obtain the shape, wherein the measuring step obtains, for obtaining the error, the shape data for each of the plurality of regions so as not to include a component having a spatial frequency higher than a spatial frequency corresponding to a maximum degree of a first polynomial representing the error.