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A system that incorporates teachings of the present disclosure may include, for example, an apparatus that includes a processor coupled with a memory where the processor is operable to obtain a first speckled pattern of a first defocused image of a neighborhood of a location on an object, to obtain

A system that incorporates teachings of the present disclosure may include, for example, an apparatus that includes a processor coupled with a memory where the processor is operable to obtain a first speckled pattern of a first defocused image of a neighborhood of a location on an object, to obtain a second speckled pattern of a second defocused image of the neighborhood, to determine a shift between the first and second speckle patterns, and to calculate slope information of a surface profile at the location based on the determined shift. Other embodiments are disclosed.

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1. A method comprising: illuminating a neighborhood of a location on an object with a first beam of coherent radiation at a first wavelength;obtaining a first defocused image of the neighborhood illuminated with the first wavelength, the first defocused image comprising a first speckle pattern;illum

1. A method comprising: illuminating a neighborhood of a location on an object with a first beam of coherent radiation at a first wavelength;obtaining a first defocused image of the neighborhood illuminated with the first wavelength, the first defocused image comprising a first speckle pattern;illuminating the neighborhood with a second beam of coherent radiation at a second wavelength;obtaining a second defocused image of the neighborhood illuminated with the second wavelength, the second defocused image comprising a second speckle pattern;determining a shift between the first and second speckle patterns; andcalculating slope information of a surface profile at the location based on the determined shift. 2. The method of claim 1, wherein the first and second beams of coherent radiation are substantially collinear. 3. The method of claim 1, comprising selecting widths of the first and second beams of coherent radiation to enable resolution of variations of the slope information at a desired spatial resolution of the surface profile. 4. The method of claim 1, wherein the determining of the shift comprises: generating a shifted digital representation of the second speckle pattern relative to a digital representation of the first speckle pattern for a trial shift value;generating a difference map between the shifted digital representation of the second speckle pattern and the digital representation of the first speckle pattern over a region of overlap of the digital representations; anddetermining the shift by selecting the trial shift value to reduce a measure of a magnitude of the difference map. 5. The method of claim 1, wherein the shift is determined to sub-pixel precision. 6. The method of claim 1, wherein the slope information is an estimate of a normal vector to a surface at the location. 7. The method of claim 1, comprising: illuminating the object at multiple locations; andobtaining the slope information from the first and second defocused images for the multiple locations. 8. The method of claim 7, wherein the first and second defocused images do not substantially overlap. 9. The method of claim 7, wherein the illumination at the multiple locations occurs simultaneously. 10. The method of claim 7, wherein the illumination at the multiple locations is produced by a beam replicating element that generates a pattern of replicated beams. 11. The method of claim 10, wherein the beam replicating element is a diffractive optical element beam splitter. 12. The method of claim 10, wherein the pattern of replicated beams is translated laterally relative to the object to acquire additional slope information for the object within gaps in prior positions of the multiple locations. 13. The method of claim 1, wherein the illuminating at a first wavelength and the illuminating at a second wavelength occur simultaneously. 14. The method of claim 13, wherein the first and second defocused images corresponding to the first wavelength and the second wavelength are displaced by a dispersive element to produce substantially non-overlapping defocused images. 15. The method of claim 14, wherein the dispersive element is a diffraction grating. 16. The method of claim 14, wherein the substantially non-overlapping defocused images corresponding to the first wavelength and the second wavelength do not substantially overlap with other defocused images that are produced when the object is illuminated at the multiple locations. 17. The method of claim 13, wherein a wavelength-selective element directs the first defocused image corresponding to the first wavelength to a first detector array or first region of a detector array and the second defocused image corresponding to the second wavelength to a second detector array or second region of the first detector array. 18. The method of claim 13, wherein a time-varying wavelength selective element alternately passes the first wavelength and the second wavelength. 19. The method of claim 13, further comprising utilizing a patterned array of wavelength-selective elements that renders adjacent pixels of a detector array alternately sensitive to the first wavelength and the second wavelength. 20. The method of claim 13, wherein the simultaneous illuminating at a first and a second wavelength is pulsed to minimize time-varying contributions to the shift that are not related to the slope information. 21. The method of claim 1, wherein the illuminating at a first wavelength and the illuminating at a second wavelength occur sequentially and the receiving of a defocused image comprises utilizing a detector array to acquire the first speckle pattern and the second speckle sequentially. 22. The method of claim 21, wherein time-varying contributions to the shift that are not related to the slope information are mitigated by pulsing the first beam of radiation and the second beam of radiation such that the pulses occur close together in time and straddle image frames of the detector array. 23. The method of claim 21, further comprising: illuminating the neighborhood of the location with a third beam of coherent radiation at a first wavelength;receiving a third defocused image of the neighborhood illuminated with the first wavelength, the third defocused image comprising a third speckle pattern;determining a second shift between the first and third speckle patterns; andutilizing the second shift between the first and the third speckle patterns to compensate for contributions to the shift between the first and the second speckle patterns that are not related to the slope information. 24. The method of claim 1, wherein the illuminating at a first wavelength and the illuminating at a second wavelength are implemented as a time-varying wavelength scan. 25. The method of claim 24, further comprising utilizing a rapidly repeating time-varying wavelength scan and a Geiger-mode avalanche photodiode array providing photon arrival times at pixels, wherein the photon arrival times map to the wavelength of the time-varying wavelength scan and the contributions to the shift that are not related to the slope information are obtained from speckle motion between points in the time-varying wavelength scan having the same wavelength. 26. The method of claim 1, wherein a variation of speckle size or motion of speckle that is caused by sideways translation of the first and second beams of coherent radiation relative to the object provide feedback for adjusting the focus of the first and second beams of coherent radiation on the object. 27. The method of claim 1, further comprising obtaining images using a boresighted camera, for registering multiple locations on the object when motion occurs between measurements. 28. The method of claim 1, wherein the object comprises a finger or a palm, and wherein the slope information identifies the location and orientation of friction ridges or location and type of minutia on the finger or the palm. 29. The method of claim 28, wherein the slope information provides the direction of steepest decent at the location on the friction ridge from which ridge orientation is determined. 30. The method of claim 1, wherein the object comprises a face or ear, and wherein the slope information provides biometric information. 31. The method of claim 1, wherein the slope information is measured at least two different times, and wherein variations in the slope information provide change detection of the surface profile of the object. 32. The method of claim 1, wherein the object is a person, and wherein a temporal variation of the slope information provides biometric gait information. 33. The method of claim 1, wherein a nominal wavelength of the first and second beams of coherent radiation is either in a violet to blue wavelength range or a shortwave infrared wavelength range. 34. The method of claim 1, wherein a nominal wavelength of the first and second beams of coherent radiation is greater than 1400 nm. 35. An apparatus comprising: a memory; anda processor coupled with the memory and operable to: obtain a first speckled pattern of a first defocused image of a neighborhood of a location on an object, the first defocused image being obtained based on a first illumination of the neighborhood by a first beam of coherent radiation at a first wavelength;obtain a second speckled pattern of a second defocused image of the neighborhood, the second defocused image being obtained based on a second illumination of the neighborhood by a second beam of coherent radiation at a second wavelength;determining a shift between the first and second speckle patterns; andcalculating slope information of a surface profile at the location based on the determined shift. 36. The apparatus of claim 35, wherein the illumination source comprises a beam replicating element that generates a pattern of replicated beams at multiple locations on the object. 37. The apparatus of claim 35, wherein the beam replicating element is a diffractive optical element beam splitter. 38. The apparatus of claim 37, further comprising a boresighted camera for registering the multiple locations on the object when motion occurs between measurements. 39. The apparatus of claim 35, further comprising: a rapidly repeating time-varying wavelength scan; anda Geiger-mode avalanche photodiode array providing photon arrival times at pixels,wherein the photon arrival times map to the wavelength of the time-varying wavelength scan and the contributions to the shift that are not related to the slope information are obtained from speckle motion between points in the time-varying wavelength scan having the same wavelength. 40. The apparatus of claim 35, further comprising an illuminating source operably coupled to the processor for generating the first and second beams of coherent radiation. 41. A non-transitory computer-readable storage medium comprising computer instructions for: illuminating a neighborhood of a location on an object with a first beam of coherent radiation at a first wavelength;obtaining a first defocused image of the neighborhood illuminated with the first wavelength, the first defocused image comprising a first speckle pattern;illuminating the neighborhood with a second beam of coherent radiation at a second wavelength; andobtaining a second defocused image of the neighborhood illuminated with the second wavelength, the second defocused image comprising a second speckle pattern,wherein a shift between the first and second speckle patterns is determined, and wherein slope information of a surface profile at the location is determined based on the shift. 42. The non-transitory computer-readable storage medium of claim 41, comprising computer instructions for determining the shift by: generating a shifted digital representation of the second speckle pattern relative to a digital representation of the first speckle pattern for a trial shift value;generating a difference map between the shifted digital representation of the second speckle pattern and the digital representation of the first speckle pattern over a region of overlap of the digital representations; anddetermining the shift by selecting the trial shift value to reduce a measure of a magnitude of the difference map. 43. The non-transitory computer-readable storage medium of claim 41, comprising computer instructions for: illuminating the object at multiple locations; andobtaining the slope information from the first and second defocused images for the multiple locations.