Patent ID: 11879721
Assignee: CARL ZEISS SMT GMBH
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 9:
10. Measurement arrangement for interferometrically determining a shape of an optical surface of a test object, comprising:
a light source for providing a first input wave having a first wavelength λ1 and a second input wave having a second wavelength λ2, which differs from the first wavelength λ1;
a diffractive optical element, which is arranged in a beam path of the first and the second input waves and is configured to produce by way of diffraction from the first and the second input waves for each of the wavelengths a first and a second test wave, which is directed at the test object and has a wavefront adapted at least partially to a desired shape of the optical surface, and also to produce a first and a second reference wave, which has a propagation direction that deviates from a propagation direction of the associated test wave,
for each of the wavelengths, a reflective optical element, which is arranged in the beam path of the respective reference wave and is designed for the back-reflection of the respective reference wave;
a capture device for capturing first and second interferograms which are produced by wavelength-appropriate superposition of the first and the second test wave after interaction with the test object and the back-reflected first and second reference waves, in each case after a further diffraction at the diffractive optical element in a capture plane; and
an evaluation device for jointly evaluating the first and the second interferogram, taking into account a difference between the first and the second wavelengths.