Patent ID: 8390822

Claim:
A method for determining three-dimensional position information of a surface of a translucent object, the method comprising: illuminating a surface of a translucent object with optical radiation from a pair of optical sources to thereby form a fringe pattern on the surface, the optical radiation having a wavelength that is predetermined to penetrate below the surface of the translucent object and to scatter the penetrated optical radiation from below the surface as a substantially uniform background intensity with respect to the fringe pattern on the surface; detecting optical radiation scattered from the fringe pattern on the surface and scattered from below the surface; changing a phase of the optical radiation emitted from one of the optical sources relative to a phase of the optical radiation emitted from the other optical source to thereby form a phase-shifted fringe pattern on the surface; detecting optical radiation scattered from the fringe pattern on the surface and scattered from below the surface after the change of the phase; and calculating three-dimensional position information of the surface of the translucent object in response to the radiation detected before and after the change of the phase.