Compensation for geometric effects of beam misalignments in plane mirror interferometers
First Claim
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1. A method comprising:
- using an interferometer in an interferometry system to produce an output beam comprising a phase related to an optical path difference between paths of two beams, at least one of which contacts a measurement object in the interferometry system, wherein the two beams are derived from an input beam and the interferometer comprises interferometer optics spaced from the measurement object;
providing precalibrated information that accounts for contributions to the optical path difference caused by a deviation of at least one of the beam paths from a nominal beam path due to an imperfection in at least one of the interferometer optics or an imperfection in a light source used to produce the input beam;
determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and the precalibrated information; and
moving the measurement object with respect to the interferometer based on the determined position.
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Abstract
Techniques for compensating for geometric effects of beam misalignment in plane mirror interferometers are disclosed.
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Citations
42 Claims
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1. A method comprising:
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using an interferometer in an interferometry system to produce an output beam comprising a phase related to an optical path difference between paths of two beams, at least one of which contacts a measurement object in the interferometry system, wherein the two beams are derived from an input beam and the interferometer comprises interferometer optics spaced from the measurement object; providing precalibrated information that accounts for contributions to the optical path difference caused by a deviation of at least one of the beam paths from a nominal beam path due to an imperfection in at least one of the interferometer optics or an imperfection in a light source used to produce the input beam; determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and the precalibrated information; and moving the measurement object with respect to the interferometer based on the determined position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method comprising:
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using an interferometer to produce an output beam comprising a phase related to an optical path difference between two beam paths, at least one of which contacts a measurement object, the interferometer comprising interferometer optics spaced from the measurement object; providing precalibrated information that accounts for contributions to the optical path difference caused by a deviation of at least one of the beam paths from a nominal beam path due to an imperfection in at least one of a light source for the interferometer and at least one of the interferometer optics; determining a displacement of the measurement object relative to the interferometer based on the precalibrated information and information derived from the output beam; and moving the measurement relative to the interferometer based on the determined displacement.
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26. A method comprising:
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correcting interferometric measurements of a position of a measurement object made by an interferometry system including an interferometer comprising interferometer optics based on precalibrated information that accounts for contributions to an optical path difference caused by a deviation of at least one beam path from a nominal beam path due to an imperfection in at least one of the interferometer optics or an imperfection in a light source from which the beam is derived, the interferometer being configured to direct a beam along the at least one beam path to reflect from a measurement object spaced from the interferometer optics; and adjusting the position of the measurement object based on the corrected interferometric measurement. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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34. A method comprising:
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calibrating an interferometry system comprising an interferometer including interferometer optics by determining information that accounts for contributions to an optical path difference caused by a deviation of at least one beam path from a nominal beam path due to an imperfection in at least one of the interferometer optics or an imperfection in a light source from which the beam is derived, the interferometer being configured to direct a beam along the at least one beam path to reflect from a measurement object spaced from the interferometer optics; and moving the measurement object relative to the interferometer based on measurements of the position of the measurement object made using the calibrated interferometry system. - View Dependent Claims (35, 36, 37)
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38. An apparatus comprising:
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an interferometer configured to produce an output beam comprising a phase related to an optical path difference between two beam paths, at least one of which contacts a measurement object, wherein the interferometer comprises interferometer optics spaced from the interferometer; and an electronic controller coupled to the interferometer, wherein during operation the electronic controller determines a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and precalibrated information that accounts for contributions to the optical path difference caused by a deviation of at least one of the beam paths from a nominal beam path due to an imperfection in at least one of a light source for the interferometer or at least one of the interferometer optics. - View Dependent Claims (39, 40, 41)
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42. An apparatus comprising an electronic storage medium storing precalibrated information that accounts for contributions to an optical path difference caused by a deviation of at least one beam path from a nominal beam path due to an imperfection in at least one of a light source for an interferometer or optics of the interferometer, the interferometer being configured to direct a beam along one of the beam paths to reflect from a measurement object spaced from the interferometer optics.
Specification