Method and apparatus for surface profilometry
First Claim
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1. 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.
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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.
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Citations
11 Claims
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1. A method for determining the surface profile of an object, comprising the steps of:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining the surface profile of an object, comprising the steps of:
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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. - View Dependent Claims (9)
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10. Apparatus for determining the surface profile of an object, comprising:
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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. - View Dependent Claims (11)
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Specification