US4641972A
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US
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Method and apparatus for surface profilometry
Assignee: New York Institute of Technology
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Filing: 1984-09-14
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Granted: 1987-02-10
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Expires: 2004-09-14
Abstract
Abstract Phase measurements of deformed grating images are used in performing improved optical profilometry. In one embodiment, phase differences between images of an object and a reference plane are used to obtain a measure of the object height.
Inventors
- 👤 Maurice Halioua
- 👤 Venugopal Srinivasan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:22
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/24; G01B11/25; G01B11/2518; G01B11/2527
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
117 words
A method for determining the surface profile of an object, comprising the steps of: directing at said object an incident beam of light having a sinusoidally varying intensity pattern; modulating the phase of the sinusoidal intensity pattern of said incident beam; receiving at a detector a deformed grating image of the object for a number of different modulated phases of said incident beam; determining, for points on the surface of the object, the height at each said point with respect to a reference plane, each said height determination including the step of combining image intensity values, for said different modulated phases of the incident beam, at a detector position corresponding to a respective point of the object.
Claim 2
Independent Claim
117 words
A method for determining the surface profile of an object, comprising the steps of: directing at said object an incident beam of light having a sinusoidally varying intensity pattern; modulating the phase of the sinusoidal intensity pattern of said incident beam; receiving at a detector a deformed grating image of the object for a number of different modulated phases of said incident beam; determining, for points on the surface of the object, the height at each said point with respect to a reference plane, each said height determination including the step of combining image intensity values, for said different modulated phases of the incident beam, at a detector position corresponding to a respective point of the object.
Claim 3
Dependent Claim
62 words
The method as defined by claim 1, wherein said intensity values at each detector pixel position are combined to determine an object phase at a corresponding object point, and wherein the difference between the object phase at each such point and a reference phase at a corresponding point on the reference plane is used to determine the object height at such point.
Claim 4
Dependent Claim
61 words
The method as defined by claim 2, wherein said reference phases are obtained by positioning a reference plane in the vicinity of the object position, and determining, for points on the reference plane, detector intensity values for said different modulated phases of said incident beam, said intensity values for each point being combined to obtain a reference phase for such point.
Claim 5
Dependent Claim
21 words
The method as defined by claim 1, wherein said number of different phases of the incident beam comprises three different phases.
Claim 6
Dependent Claim
21 words
The method as defined by claim 3, wherein said number of different phases of the incident beam comprises three different phases.
Claim 7
Dependent Claim
86 words
The method as defined by claim 1, wherein reference phases are obtained by positioning a reference plane in the vicinity of the object position, and determining, for points on the reference plane, detector intensity values for said different modulated phases of said incident beam, said intensity values for each point being combined to obtain a reference phase for such point; and wherein said step of determining height includes determining the distance between positions on the detector at which a reference phase corresponds to an object phase.
Claim 8
Dependent Claim
21 words
The method as defined by claim 6, wherein said number of different phases of the incident beam comprises three different phases.
Claim 9
Independent Claim
149 words
A method for determining the surface profile of an object, comprising the steps of: directing at said object an incident beam of light having a sinusoidally varying intensity pattern; modulating the phase of the sinusoidal pattern of said incident beam; receiving and storing a deformed grating image of the object for a number of different modulated phases of said input beam; receiving and storing an image of a reference plane for said number of different modulated phases of said input beam; combining image intensity values at each point of the deformed grating image of the object to obtain an object phase at each such point; combining image intensity values at each point of the image of the reference plane to obtain a reference plane phase at each such point; and determining the object height at each point from the object phase and reference plane phase for each such point.
Claim 10
Independent Claim
149 words
A method for determining the surface profile of an object, comprising the steps of: directing at said object an incident beam of light having a sinusoidally varying intensity pattern; modulating the phase of the sinusoidal pattern of said incident beam; receiving and storing a deformed grating image of the object for a number of different modulated phases of said input beam; receiving and storing an image of a reference plane for said number of different modulated phases of said input beam; combining image intensity values at each point of the deformed grating image of the object to obtain an object phase at each such point; combining image intensity values at each point of the image of the reference plane to obtain a reference plane phase at each such point; and determining the object height at each point from the object phase and reference plane phase for each such point.
Claim 11
Dependent Claim
39 words
The method as defined by claim 8, wherein the difference between the object phase at each point and the reference phase at a corresponding point on the reference plane is used to determine the object height at such point.
Claim 12
Dependent Claim
117 words
Apparatus for determining the surface profile of an object, comprising: means for directing at said object an incident beam of light having a sinusoidally varying intensity pattern; means for modulating the phase of the sinusoidal intensity pattern of said incident beam; a detector for receiving a deformed grating image of the object for a number of different modulated phases of said incident beam; and means for determining, for points on the surface of the object, the height at each said point with respect to a reference plane, said means being operative to combine image intensity values, for said different modulated phases of the incident beam, at a detector position corresponding to a respective point of the object.
Claim 13
Dependent Claim
117 words
Apparatus for determining the surface profile of an object, comprising: means for directing at said object an incident beam of light having a sinusoidally varying intensity pattern; means for modulating the phase of the sinusoidal intensity pattern of said incident beam; a detector for receiving a deformed grating image of the object for a number of different modulated phases of said incident beam; and means for determining, for points on the surface of the object, the height at each said point with respect to a reference plane, said means being operative to combine image intensity values, for said different modulated phases of the incident beam, at a detector position corresponding to a respective point of the object.
Claim 14
Dependent Claim
66 words
Apparatus as defined by claim 10, wherein said determining means is operative to combine intensity values at each detector pixel position to determine an object phase at a corresponding object point, and is operative to obtain the difference between the object phase at each such point and a reference phase at a corresponding point on the reference plane to determine the object height at such point.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-09 | 1990-08-11 | 1991-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-09 | 1994-08-11 | 1995-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-09 | 1998-08-11 | 1999-02-10 | $7700.00 | Window Closed / Lapsed |