Angle interferometers
First Claim
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1. A method, comprising:
- directing a beam to reflect from an interface of a first optical element at a non-normal angle, the beam having an s-polarized component and a p-polarized component at the interface,wherein the non-normal reflection at the interface introduces a phase change upon reflection for the s-polarized component and a phase change upon reflection for the p-polarized component, where the phase changes upon reflection for the s-polarized and p-polarized components differ from one another by an amount that varies depending on the incident angle of the beam at the interface;
detecting the beam after it has reflected from the interface;
measuring an optical interference signal from the detected beam, wherein the optical interference signal comprises an interference phase related to the phase changes upon reflection between the s-polarized and p-polarized components of the beam; and
determining information about the incident angle of the beam at the interface based on the measured optical interference signal.
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Abstract
Methods and systems for determining information about the incident angle of a beam are disclosed, the method including directing a beam having an s-polarized component and a p-polarized component to reflect from an interface at a non-normal angle, where the non-normal reflection introduces for each component a phase change upon reflection that is different for each component, and measuring an optical interference signal related to the phase change between the components of the reflected beam.
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Citations
45 Claims
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1. A method, comprising:
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directing a beam to reflect from an interface of a first optical element at a non-normal angle, the beam having an s-polarized component and a p-polarized component at the interface, wherein the non-normal reflection at the interface introduces a phase change upon reflection for the s-polarized component and a phase change upon reflection for the p-polarized component, where the phase changes upon reflection for the s-polarized and p-polarized components differ from one another by an amount that varies depending on the incident angle of the beam at the interface; detecting the beam after it has reflected from the interface; measuring an optical interference signal from the detected beam, wherein the optical interference signal comprises an interference phase related to the phase changes upon reflection between the s-polarized and p-polarized components of the beam; and determining information about the incident angle of the beam at the interface based on the measured optical interference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 42, 43, 44, 45)
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22. A system, comprising:
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an interferometer which during operation produces an output beam comprising information about the position of a measurement object relative to the interferometer; a first assembly configured to derive a primary beam from the output beam and to direct the primary beam along a beam path; a first optical element having an interface positioned relative to the beam path so that the primary beam reflects from the interface at a non-normal angle, the primary beam having an s-polarized component and a p-polarized component at the interface, wherein the non-normal reflection at the interface introduces a phase change upon reflection for the s-polarized component and a phase change upon reflection of the p-polarized component, where the phase changes upon reflection for the s-polarized and p-polarized components differ from one another by an amount that varies depending on the incident angle of the primary beam at the interface; a detector positioned to receive the primary beam after it reflects from the interface; and an electronic processor coupled to the detector and configured to measure an optical interference signal related to the phase changes upon reflection between the s-polarized and p-polarized components of the primary beam, and to determine information about the incident angle of the beam at the interface based on the measured optical interference signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification