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US 2022/0187061 A1Published application
Method for calibrating a measuring apparatus
AssigneeCarl Zeiss SMT GmbH
InventorsJochen HETZLER, Stefan SCHULTE, Matthias DREHER
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AssigneeCarl Zeiss SMT GmbH
InventorsJochen HETZLER, Stefan SCHULTE, Matthias DREHER
Estimating the term…
A method for calibrating a measuring device (10) for interferometrically determining a shape of an optical surface (12) of an object under test (14). The measuring device includes a module plane (32) for arranging a diffractive optical test module (30) which is configured to generate a test wave (34) that is directed at the optical surface and that has a wavefront at least approximately adapted to a target shape (60) of the optical surface. The method includes: arranging a diffractive optical calibration module (44) in the module plane for generating a calibration wave (80), acquiring a calibration interferogram (88) generated using the calibration wave in a detector plane (43) of the measuring device, and determining a position assignment distribution (46) of points (52) in the module plane to corresponding points (54) in the detector plane from the acquired calibration interferogram.
A method for calibrating a measuring device for interferometrically determining a shape of an optical surface of an object under test, wherein the measuring device comprises a module plane for the arrangement of a diffractive optical test module which is configured to generate a test wave that is a directed at the optical surface and that has a wavefront at least approximately adapted to a target shape of the optical surface, said method comprising:
An optical element comprising an optical surface, wherein the optical surface is assigned a non-rotationally symmetric target shape, a maximum deviation of which from a best-adapted rotationally symmetric reference surface is between 100 nm and 100 μm and wherein a maximum deviation of an actual shape of the optical surface from the target shape is no more than 1/1000 of the maximum deviation of the target shape from the rotationally symmetric reference surface.
A diffractive optical element comprising a diffractive structure pattern which has a grating-shaped basic structure having a modulation such that a determination of the diffractive structure pattern with an interferogram recorded by a detector is performed with an accuracy that is better than a pitch between two adjacent pixels of the detector, wherein the interferogram is generated by superimposing a wave extending across the diffractive structure pattern with a reference wave.
Dependencies are inferred from the claim text.