Patent ID: 8345262

Claim:
A method of determining a deviation of an actual shape from a desired shape of an optical surface, comprising: providing an incoming electromagnetic measuring wave, providing two diffractive structures, calibrating at least one of the two diffractive structures by radiating the incoming measuring wave onto the at least one diffractive structure to be calibrated, and determining a calibration deviation of the actual wavefront from a desired wavefront of the measuring wave after interaction of the actual wavefront with the at least one diffractive structure to be calibrated, positioning the two diffractive structures in the optical path of the incoming measuring wave such that individual rays of the measuring wave radiate through both diffractive structures, and reshaping the incoming measuring wave using the two diffractive structures to form an adapted measuring wave the wavefront of which is adapted to the desired shape of the optical surface, positioning the optical surface in the optical path of the adapted measuring wave so that the adapted measuring wave interacts with the optical surface, and measuring the wavefront of the adapted measuring wave after interaction of the adapted measuring wave with the optical surface.