Compensating for effects of non-isotropic gas mixtures in interferometers
First Claim
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1. A method, comprising:
- making an interferometry measurement in a chamber, the chamber having an atmosphere that has a first value of an intrinsic refractive property;
introducing a secondary gas into the chamber to adjust a composition of the chamber atmosphere; and
introducing a compensating gas into the chamber, wherein the compensating gas reduces variations in the intrinsic refractive property of the atmosphere from the first value caused by the introduction of the secondary gas.
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Abstract
Methods and apparatus for reducing the effects of non-isotropic gas distributions on interferometry measurements are disclosed.
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Citations
42 Claims
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1. A method, comprising:
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making an interferometry measurement in a chamber, the chamber having an atmosphere that has a first value of an intrinsic refractive property;
introducing a secondary gas into the chamber to adjust a composition of the chamber atmosphere; and
introducing a compensating gas into the chamber, wherein the compensating gas reduces variations in the intrinsic refractive property of the atmosphere from the first value caused by the introduction of the secondary gas. - 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, 25, 26, 27, 28)
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29. A system, comprising:
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a movable stage;
an interferometry system configured to measure a position of the movable stage along a measurement path;
a chamber housing the movable stage and the interferometry system, the chamber having an atmosphere that has a first value of an intrinsic refractive property; and
secondary and compensating gas sources configured to introduce a secondary gas and compensating gas into the chamber, wherein the compensating gas reduces variations in the intrinsic refractive property of the atmosphere from the first value caused by the introduction of the secondary gas. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification