CPC G01B 11/2441 (2013.01) [G01B 9/02039 (2013.01); G01B 9/02072 (2013.04); G01M 11/005 (2013.01); G01M 11/0271 (2013.01); G02B 5/0891 (2013.01)] | 11 Claims |
1. A measurement apparatus for interferometrically determining a shape of a surface of a test object, comprising:
a radiation source providing an input wave,
a multiply-encoded diffractive optical element, which is configured to produce by diffraction from the input wave a test wave, which is directed at the test object and has a wavefront formed as a free-form surface, as well as at least one calibration wave,
wherein the calibration wave has a wavefront with a non-rotationally symmetric shape, wherein cross sections through the wavefront of the calibration wave along cross-sectional surfaces aligned transversely to one another each have a respective curved shape and wherein the respective curved shapes in the cross-sectional surfaces differ in terms of an opening parameter, and
a capture device for capturing a calibration interferogram formed by superimposing a reference wave with the calibration wave after interaction with a calibration object.
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