Interferometer for the measurement of surface profile which introduces a spatial carrier by tilting the reference mirror

Claim 1

A method for measuring a shape of a surface with an interferometer comprising the steps of: (a) positioning a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces with a phase shift device; (c) detecting a response of said phase shift device based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes; (d) analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said response and said measured interference fringes; and (e) subtracting said spatial carrier from the analyzed wavefront data in order to analyze the shape of said surface to be measured.

Claim 2

A method for measuring a shape of a surface with an interferometer comprising the steps of: (a) positioning a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces with a phase shift device; (c) detecting a response of said phase shift device based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes; (d) analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said response and said measured interference fringes; and (e) subtracting said spatial carrier from the analyzed wavefront data in order to analyze the shape of said surface to be measured.

Claim 7

A method for detecting an amount of movement of a surface to be measured comprising the steps of: (a) tilting a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces with respect to the other of said surfaces without altering the degree of tilt between said surfaces; and (c) detecting an amount of movement of said at least one of said surfaces based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes.

Claim 8

A method for detecting an amount of movement of a surface to be measured comprising the steps of: (a) tilting a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces with respect to the other of said surfaces without altering the degree of tilt between said surfaces; and (c) detecting an amount of movement of said at least one of said surfaces based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes.

Claim 12

A method for detecting an amount of movement of a surface to be measured comprising the steps of: (a) tilting a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces; and (c) detecting an amount of movement of said at least one of said surfaces based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes, wherein the amount of movement detected is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 13

A method for detecting an amount of movement of a surface to be measured comprising the steps of: (a) tilting a reference surface relative to a surface to be measured and superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting at least one of said surfaces; and (c) detecting an amount of movement of said at least one of said surfaces based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes, wherein the amount of movement detected is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 14

A method for deriving a calibration curve of a phase shift device comprising the steps of: (a) superimposing wavefronts reflected from a reference surface and a surface to be driven by said phase shift device, said reference surface and said surface to be driven being tilted with respect to one another so that interference fringes produced by said superimposition contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting said surface to be driven by varying an applied voltage to said phase shift device; (c) detecting a displacement resultant from said shifting of said surface, based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes; and (d) deriving a calibration curve based on said displacement and said applied voltage.

Claim 15

A method for deriving a calibration curve of a phase shift device comprising the steps of: (a) superimposing wavefronts reflected from a reference surface and a surface to be driven by said phase shift device, said reference surface and said surface to be driven being tilted with respect to one another so that interference fringes produced by said superimposition contain a spatial carrier; (b) measuring said interference fringes at a plurality of times while shifting said surface to be driven by varying an applied voltage to said phase shift device; (c) detecting a displacement resultant from said shifting of said surface, based on a wavelength of light used to form said interference fringes and an amount of movement of said measured interference fringes; and (d) deriving a calibration curve based on said displacement and said applied voltage.

Claim 17

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein said detecting means detects an amount of movement of said at least one of said surfaces by applying a spatial fringe scan method to said measurements of interference fringes; and wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a tilt.

Claim 18

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein said detecting means detects an amount of movement of said at least one of said surfaces by applying a spatial fringe scan method to said measurements of interference fringes; and wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a tilt.

Claim 19

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein said detecting means detects an amount of movement of said at least one of said surfaces by applying a spatial fringe scan method to said measurements of interference fringes; and wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 20

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein said detecting means detects an amount of movement of said at least one of said surfaces by applying a spatial fringe scan method to said measurements of interference fringes; and wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 21

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average.

Claim 22

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average.

Claim 23

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said. superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a tilt.

Claim 24

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said. superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a tilt.

Claim 25

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 26

An apparatus for detecting an amount of movement of a surface to be measured comprising: means for tilting a reference surface relative to a surface to be measured; means for superimposing wavefronts reflected from said reference surface and said surface to be measured, wherein said reference surface and said surface to be measured are tilted relative to one another so that interference fringes produced by said superimposing contain a spatial carrier; means for measuring said interference fringes a plurality of times while shifting at least one of said surfaces; and means for detecting an amount of movement of said at least one of said surfaces based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; wherein the amount of movement detected by said detecting means applying a spatial fringe scan method is a function of phase differences between said wavefronts, with components of said phase differences comprising an average and a focus error.

Claim 27

An apparatus for deriving a calibration curve of a phase shift device comprising: a phase shift device for driving a surface; means for superimposing wavefronts reflected from a reference surface and said surface which is driven by said phase shift device, said reference surface and said surface which is driven being tilted with respect to one another so that interference fringes produced by said superimposition contain a spatial carrier; means for measuring said interference fringes at a plurality of times while shifting said surface which is driven by varying an applied voltage to said phase shift device; means for detecting a displacement resultant from said shifting of said surface, based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; and means for deriving a calibration curve based on said displacement and said applied voltage.

Claim 28

An apparatus for deriving a calibration curve of a phase shift device comprising: a phase shift device for driving a surface; means for superimposing wavefronts reflected from a reference surface and said surface which is driven by said phase shift device, said reference surface and said surface which is driven being tilted with respect to one another so that interference fringes produced by said superimposition contain a spatial carrier; means for measuring said interference fringes at a plurality of times while shifting said surface which is driven by varying an applied voltage to said phase shift device; means for detecting a displacement resultant from said shifting of said surface, based on a wavelength of light forming said interference fringes and an amount of movement of said measured interference fringes; and means for deriving a calibration curve based on said displacement and said applied voltage.

Claim 31

An apparatus for measuring a shape of a surface comprising: an optical system for superimposing wavefronts reflected from a reference surface and a surface to be measured, wherein interference fringes produced by said superimposing contain a spatial carrier; a phase shift device for varying at least one of an optical path length of said reference surface, and an optical path length of said surface to be measured; means for measuring said interference fringes a plurality of times while varying at least one of said optical path lengths with said phase shift device; means for detecting a response due to said varying, based on a spatial fringe scan method; means for analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said detected response and said measured interference fringes; and means for subtracting said spatial carrier from the analyzed wavefront in order to measure the shape of said surface to be measured.

Claim 32

An apparatus for measuring a shape of a surface comprising: an optical system for superimposing wavefronts reflected from a reference surface and a surface to be measured, wherein interference fringes produced by said superimposing contain a spatial carrier; a phase shift device for varying at least one of an optical path length of said reference surface, and an optical path length of said surface to be measured; means for measuring said interference fringes a plurality of times while varying at least one of said optical path lengths with said phase shift device; means for detecting a response due to said varying, based on a spatial fringe scan method; means for analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said detected response and said measured interference fringes; and means for subtracting said spatial carrier from the analyzed wavefront in order to measure the shape of said surface to be measured.

Claim 35

An apparatus for measuring a shape of a surface comprising: an optical system for superimposing wavefronts reflected from a reference surface and a surface to be measured, wherein interference fringes produced by said superimposing contain a spatial carrier; a phase shift device for varying at least one of an optical path length of said reference surface, and an optical path length of said surface to be measured; means for measuring said interference fringes a plurality of times while varying at least one of said optical path lengths with said phase shift device; means for detecting a response due to said varying, based on an amount of movement of said interference fringes and a wavelength of light used to form said interference fringes; means for analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said detected response and said measured interference fringes; and means for subtracting said spatial carrier from the analyzed wavefront in order to measure the shape of said surface to be measured.

Claim 36

An apparatus for measuring a shape of a surface comprising: an optical system for superimposing wavefronts reflected from a reference surface and a surface to be measured, wherein interference fringes produced by said superimposing contain a spatial carrier; a phase shift device for varying at least one of an optical path length of said reference surface, and an optical path length of said surface to be measured; means for measuring said interference fringes a plurality of times while varying at least one of said optical path lengths with said phase shift device; means for detecting a response due to said varying, based on an amount of movement of said interference fringes and a wavelength of light used to form said interference fringes; means for analyzing said superimposed wavefronts and said interference fringes containing a spatial carrier produced therefrom, by a temporal fringe scan method based on said detected response and said measured interference fringes; and means for subtracting said spatial carrier from the analyzed wavefront in order to measure the shape of said surface to be measured.