US 11,892,283 B2
Measuring apparatus for interferometrically determining a surface shape
Stefan Schulte, Stoedlen (DE); and Rolf Freimann, Aalen (DE)
Assigned to CARL ZEISS SMT GMBH, Oberkochen (DE)
Filed by Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed on Mar. 30, 2022, as Appl. No. 17/708,409.
Application 17/708,409 is a continuation of application No. PCT/EP2020/076557, filed on Sep. 23, 2020.
Claims priority of application No. 10 2019 214 979.0 (DE), filed on Sep. 30, 2019.
Prior Publication US 2022/0221269 A1, Jul. 14, 2022
Int. Cl. G01B 11/24 (2006.01); G01B 9/02 (2022.01); G01M 11/00 (2006.01); G01B 9/02055 (2022.01); G01M 11/02 (2006.01); G02B 5/08 (2006.01)
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
OG exemplary drawing
 
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.