Method for profiling an object surface using a large equivalent wavelength and system therefor

Claim 3

A method for profiling an object surface in accordance with claim 1 wherein said measurement data generating step comprises the step of transducing said interference pattern over an array of image pixels.

Claim 4

A method for profiling an object surface in accordance with claim 2 wherein said transducing step comprises the step of transducing said interference pattern with a camera means comprising an array of photodetectors.

Claim 5

A method for profiling an object surface in accordance with claim 2 wherein said analyzing step comprises the step of analyzing said measurement data by computer means.

Claim 6

A method for profiling an object surface in accordance with claim 1 wherein said analyzing step comprises the step of analyzing said measurement data by computer means.

Claim 7

A method for profiling an object surface in accordance with claim 1 wherein said measurement data generating step comprises the step of providing a known scan position for which said fringe contrast is a maximum for providing a measure of the relative height of a particular surface point on said object surface.

Claim 8

A method for profiling an object surface in accordance with claim 1 wherein said measurement data generating step further comprises the step of transforming said interference pattern into a spatial frequency domain, and said analyzing step comprises the step of examining phase of said transformed interference pattern as a function of spatial frequency for providing the surface height for each point on said object surface.

Claim 9

A method for profiling an object surface in accordance with claim 7 wherein said transforming step comprises the step of transforming said interference pattern into said spatial frequency domain by Fourier analysis.

Claim 10

A method for profiling an object surface in accordance with claim 1 wherein said illuminating step comprises the step of illuminating said desensitized interferometer means with a laser light source.

Claim 11

A method for profiling an object surface in accordance with claim 1 wherein said illuminating step comprises the step of illuminating said desensitized interferometer means with an incandescent lamp light source.

Claim 12

A method for profiling an object surface in accordance with claim 1 wherein said illuminating step comprises the step of illuminating said desensitized interferometer means with a light emitting diode light source.

Claim 13

A method for profiling an object surface in accordance with claim 1 wherein said illuminating step further comprises the step of providing high contract desensitized interference fringes within a depth range comprising said equivalent coherence length.

Claim 14

A method for profiling an object surface in accordance with claim 1 wherein said measurement data generating step comprises the step of depth scanning said object for providing said variation of intensity as a function of said scan position.

Claim 15

A method for profiling an object surface in accordance with claim 13 wherein said depth scanning step comprises the step of displacing said object in a direction substantially perpendicular to the surface illuminated by said desensitized interferometer means.

Claim 16

A method for profiling an object surface in accordance with claim 14 wherein said measurement data generating step further comprise the step of performing a plurality of intensity measurements during a continuous depth scan of said object for providing an array of interferograms, one for each of said image pixels.

Claim 17

A method for profiling an object surface in accordance with claim 13 wherein said measurement data generating step further comprises the step of performing a plurality of intensity measurements during a continuous depth scan of said object for providing an array of interferograms, one for each of said image pixels.

Claim 18

A method for profiling an object surface in accordance with claim 1 wherein said range with said equivalent coherence length comprises a depth range given by the expression |p+z-z 0 |≦L/2 wherein L is said equivalent coherence length, p is the local surface height on said object surface, z is the scan position, and zo is a constant, whereby p varies with the position on said object surface and comprises a measure of the object surface topography.

Claim 19

A method for profiling an object surface in accordance with claim 1 wherein said measurement data generating step comprise the step of displacing said object with respect to said desensitized interferometer means by a known amount while substantially at the same time recording photodetector data in electronic memory means.

Claim 20

A method for profiling an object surface in accordance with claim 18 wherein said measurement data generating step further comprises the step of transducing said interference pattern over an array of image pixels for providing said photodetector data.

Claim 21

A method for profiling an object surface in accordance with claim 1 wherein said convenient working distance is greater than the depth of the structure on said object surface.

Claim 22

A method for profiling an object surface in accordance with claim 1 wherein said signal comprises an approximately oscillatory signal.

Claim 23

A method for profiling an object surface in accordance with claim 18 wherein said signal comprises an approximately oscillatory signal.

Claim 24

An optical profiler system for measuring the surface profile of an object, said system comprising illumination means, said illumination means having an associated wavelength; desensitized interferometer means disposed with respect to said illumination means for being illuminated thereby, said interferometer means illuminating said object with a plurality of beams in substantially the same place but at different angles of incidence, said interferometer means having an associated equivalent wavelength larger than said illumination means associated wavelength and an associated equivalent coherence length, said interferometer means being capable of creating high contrast interference fringes within a range defined by said equivalent coherence length for said interferometer means; detection means disposed with respect to said interferometer means for detecting an interference pattern; scanning means for mounting said object thereon and disposed for displacing said object with respect to the surface illuminated by said interferometer means for providing depth scanning for said object for providing a variation of intensity as a function of scan position, said variation of intensity comprising a signal related to said equivalent wavelength modulated by an equivalent coherence signal envelope that limits any interference effect to said range, said signal corresponding to said interference fringes, said equivalent coherence envelope corresponding to said fringe contrast for said fringes, said detection means detecting said intensity variation for providing an interferogram for at least one image pixel in view of said profiler; and means for providing a surface height on said object surface corresponding to said at least one image pixel.

Claim 25

An optical profiler system for measuring the surface profile of an object, said system comprising illumination means, said illumination means having an associated wavelength; desensitized interferometer means disposed with respect to said illumination means for being illuminated thereby, said interferometer means illuminating said object with a plurality of beams in substantially the same place but at different angles of incidence, said interferometer means having an associated equivalent wavelength larger than said illumination means associated wavelength and an associated equivalent coherence length, said interferometer means being capable of creating high contrast interference fringes within a range defined by said equivalent coherence length for said interferometer means; detection means disposed with respect to said interferometer means for detecting an interference pattern; scanning means for mounting said object thereon and disposed for displacing said object with respect to the surface illuminated by said interferometer means for providing depth scanning for said object for providing a variation of intensity as a function of scan position, said variation of intensity comprising a signal related to said equivalent wavelength modulated by an equivalent coherence signal envelope that limits any interference effect to said range, said signal corresponding to said interference fringes, said equivalent coherence envelope corresponding to said fringe contrast for said fringes, said detection means detecting said intensity variation for providing an interferogram for at least one image pixel in view of said profiler; and means for providing a surface height on said object surface corresponding to said at least one image pixel.

Claim 26

An optical profiler system in accordance with claim 23 wherein said detection means comprises means for providing an interferogram for each image pixel in said field of view, said surface height providing means comprising means for providing said surface height for each of said image pixels.

Claim 27

An optical profiler system in accordance with claim 23 wherein said scanning means comprises means for providing a continuous depth scan of said object, said detection means performing a plurality of intensity measurements during said continuous depth scanning of said object.

Claim 28

An optical profiler system in accordance with claim 25 wherein said detection means further comprises storage means for storing said detected interferogram, said surface height providing means providing said surface height from said stored interferogram.

Claim 29

An optical profiler system in accordance with claim 23 wherein said range is given by the expression |p+z-z 0 |≦L/2 where L is said equivalent coherence length, is the local surface height, z is the scan position, and zo is a constant, whereby p varies with the position on said object surface and comprises a measure of the object surface topography.

Claim 30

An optical profiler system in accordance with claim 23 wherein said illumination means comprises a source of spatially incoherent illumination.

Claim 31

An optical profiler system in accordance with claim 23 wherein said illumination means comprises a laser.

Claim 32

An optical profiler system in accordance with claim 23 wherein said illumination means comprises an incandescent lamp.

Claim 33

An optical profiler system in accordance with claim 23 wherein said illumination means comprises light emitting diode means.

Claim 34

An optical profiler system in accordance with claim 23 wherein said signal comprises an approximately oscillatory signal.

Claim 35

An optical profiler system in accordance with claim 23 wherein said detection means comprises photodetector means, said scanning means comprising means for displacing said object with respect to said interferometer means by a known amount while substantially at the same time detecting said intensity variation with said photodetector means.