US 11,927,500 B2
Method and device for characterizing the surface shape of an optical element
Steffen Siegler, Oberkochen (DE); Johannes Ruoff, Aalen (DE); Alexander Wolf, Essingen (DE); Michael Carl, Aalen (DE); Toralf Gruner, Aalen (DE); and Thomas Schicketanz, Aalen (DE)
Assigned to CARL ZEISS SMT GMBH, Oberkochen (DE)
Filed by Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed on Apr. 14, 2022, as Appl. No. 17/720,344.
Application 17/720,344 is a continuation of application No. PCT/EP2020/075737, filed on Sep. 15, 2020.
Claims priority of application No. 10 2019 215 707.6 (DE), filed on Oct. 14, 2019.
Prior Publication US 2022/0236139 A1, Jul. 28, 2022
Int. Cl. G01M 11/00 (2006.01); G01B 9/02 (2022.01); G01B 9/02001 (2022.01); G01B 11/24 (2006.01)
CPC G01M 11/005 (2013.01) [G01B 9/02011 (2013.01); G01B 9/02039 (2013.01); G01B 11/2441 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method for characterizing a surface shape of an optical element, the method comprising:
a) carrying out at least one first interferogram measurement, said first interferogram measurement being carried out on the optical element in an interferometric test arrangement by superposing a reference wave, which has not been reflected at the optical element, on a test wave, which has been generated by diffraction of electromagnetic radiation at a diffractive element and reflected at the optical element;
b) carrying out second interferogram measurements, said second interferogram measurements being carried out on a calibration mirror for determining calibration corrections, wherein the second interferogram measurements comprise a first-polarization-state measurement and a second-polarization-state measurement, wherein the first-polarization state differs from the second-polarization state; and
c) determining a figure of the optical element based on both the first interferogram measurement carried out on the optical element and on the determined calibration corrections.