US 12,455,157 B2
Single frame-tilted wave interferometer
Christof Pruß, Ostfildern (DE); and Christian Schober, Ilsfeld (DE)
Assigned to UNIVERSITÄT STUTTGART, Stuttgart (DE)
Appl. No. 18/037,819
Filed by Universität Stuttgart, Stuttgart (DE)
PCT Filed Nov. 22, 2021, PCT No. PCT/EP2021/082534
§ 371(c)(1), (2) Date May 19, 2023,
PCT Pub. No. WO2022/106694, PCT Pub. Date May 27, 2022.
Claims priority of application No. 10 2020 130 814.0 (DE), filed on Nov. 20, 2020.
Prior Publication US 2024/0003672 A1, Jan. 4, 2024
Int. Cl. G01B 9/02001 (2022.01); G01B 9/02 (2022.01); G01B 9/02015 (2022.01); G01M 11/00 (2006.01)
CPC G01B 9/02007 (2013.01) [G01B 9/02027 (2013.01); G01B 9/02032 (2013.01); G01M 11/005 (2013.01); G01B 9/02039 (2013.01); G01B 2290/50 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An interferometer for the areal measurement of a surface or an optical thickness of an optically smooth test object, wherein the interferometer is configured to:
illuminate the optically smooth test object with a plurality of illumination configurations, wherein each illumination configuration is produced by a plurality of object waves with which the test object is illuminated; and
superimpose object waves influenced by the test object by means of reflection on the surface being measured or by means of transmission through the test object onto reference waves coherent with the object waves on at least one image capture device (K), to produce interferograms,
wherein each illumination configuration is realized by object waves having wavelengths of a continuous wavelength region with a central wavelength which is specific to the wavelength region,
wherein a first of the illumination configurations has only object waves of a wavelength region having a first central wavelength,
wherein a second of the illumination configurations has only object waves of a wavelength region having a second central wavelength,
wherein a third of the illumination configurations has only object waves of a wavelength region having a third central wavelength,
wherein the first central wavelength is different from the second central wavelength,
wherein the third central wavelength is different from the first central wavelength and from the second central wavelength,
wherein object waves which propagate in closest adjacent directions do not contain wavelengths of the same wavelength region,
wherein the interferometer is configured to illuminate the test object simultaneously with object waves of the first illumination configuration, the second illumination configuration and the third illumination configuration from discretely different directions, and, following an interaction with the test object, to superimpose object waves returning therefrom on the image capture device, and
wherein the image capture device is configured to spectrally decompose the interferograms produced by the superposition into wavelength-specific partial interferograms.