Method and apparatus for measuring aspherical shape and method for manufacturing optical element using them

摘要

An aspherical reference surface 2 is manufactured with such a shape accuracy that an interference band appears according to the aspherical shape of a surface 1 to be measured, an aspherical wave front 3 is formed using the reference surface, and a large aspherical surface is measured from interference within a short time. The aspherical reference surface is an aspherical surface optical element 10 manufactured by fly-cutting or ELID-grinding, that produces the interference band from light reflected from the aspherical surface and predetermined reference light, and thereby measures the shape of the aspherical surface from interference. The aspherical surface optical element should be an aspherical reflecting mirror with such a shape accuracy that an interference band is generated and parallel light is reflected in the direction normal to the surface to be measured. Thus, the shape can be measured in a short time without using an aspherical surface standard. <IMAGE>