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US 2024/0401928 A1Published application
Determination of a change of object's shape
AssigneeNikon Corporation
InventorsEric Peter Goodwin, Goldie Goldstein
Life of this patent
Estimating the term…
Abstract
Surface changes are estimated using multiple speckle interferograms acquired using beams incident at different angles. Beam irradiation conditions can be changed to increase signal to noise ratio with averaging, such as weighted averaging. Irradiation conditions can be varied with a tilt plate, a wedge, or by changing beam wavelengths.
Claims26
A method for determining a change in a shape a surface, comprising:
- with the surface in a first state and with an initial first irradiation condition and an initial second irradiation condition:
- (a) collecting a first distribution and a second distribution of radiation in an input plane of a measurement unit, the first distribution and the second distribution of radiation received from the surface in response to irradiation of the surface with a first beam at an initial first irradiation condition and second beam at an initial second irradiation condition;
- (b) processing each of the first and second distributions of radiation associated with the surface in the first state to produce corresponding first and second wavefronts, introducing a shear between the first and second wavefronts, and directing overlapped first and second wavefronts to a radiation detector to produce a first image and a second image of the surface in the first state;
- (c) based on the first image and the second image of the surface in the first state, obtaining corresponding first and second phase maps associated with the surface in the first state;
- changing at least one geometrical parameter or at least one spectral parameter for each of the initial first and second irradiation conditions from initial values to produce modified first and second irradiation conditions;
- and
- repeating steps (a)-(c) to obtain first and second phase maps.
4 more elements
A shape measurement system, comprising:
- an optical system coupled to produce speckle interferograms of a surface in a first state and a second state, the speckle interferograms associated with beams incident to the surface at least two angles of incidence;
- and
- a processing system coupled to the optical system and configured to vary irradiation conditions of the beams and produce a surface map based on a plurality of speckle interferograms associated with the varied irradiation conditions.
Dependencies are inferred from the claim text.