METHOD OF MEASURING A DEVIATION OF AN ACTUAL SHAPE FROM A TARGET SHAPE OF AN OPTICAL SURFACE

摘要

A method of measuring a deviation of an actual shape from a target shape of an optical surface of a test object, wherein the target shape is symmetrical about a rotational axis, the optical surface comprises an apex being traversed by the rotational axis, and a sub area of the optical surface includes the apex, comprises the steps of: generating an incoming light wave; diffracting the incoming light wave at a diffractive surface of a diffractive optical element and thereby generating a test wave having a wave front in the shape of the target shape, wherein the test wave is incident on the optical surface in auto collimation such that the test wave covers the apex of the optical surface and each single ray of the test wave being incident on the subareas of the optical surface is tilted with respect to a surface normal of the diffractive surface when emanating from the diffractive element; and interferometrically measuring a wave front of the test wave having interacted with the optical surface.