| CPC G01B 11/2441 (2013.01) [G01Q 60/24 (2013.01); G02B 5/18 (2013.01); G02B 5/32 (2013.01)] | 20 Claims |
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1. A diffractive optical element for a test interferometer for measuring a shape of an optical surface, comprising:
diffractive shape measuring structures arranged on a used surface of the diffractive optical element and configured to adapt a wavefront of test radiation to form a test wave for irradiating the optical surface to be measured when the diffractive optical element is arranged in the test interferometer, and
at least one test field configured to facilitate measuring a plurality of profile properties of test structures contained in the test field,
wherein the profile properties characterize a profile line of the test structures extending transversely with respect to the used surface and comprise a flank angle of the profile line of the test structures, a profile depth of the test structures and a depth of a microtrench which occurs in a bottom region of a trench-shaped profile of the test structures, and
wherein the test field is arranged at one location of the used surface instead of the diffractive shape measuring structures such that the test field is surrounded by a plurality of the diffractive shape measuring structures.
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