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 (14A, 14B) to thereby project a fringe pattern on the surface, wherein the pair of optical sources comprises a master optical source to generate the optical radiation and a pair of optical fibers each in communication with the master optical source to receive the optical radiation and each having an exit end for emitting the optical radiation, the object having a wavelength-dependent transmittance characteristic and a wavelength-dependent reflectance characteristic, 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 constant background intensity with respect to the fringe pattern on the surface, the optical radiation from each optical source (14A, 14B) being coherent with respect to the optical radiation emitted from the other optical source (14A, 14B); controlling, including controlling the separation of the fiber exit ends, the spatial frequency of the fringe pattern to be a predetermined value at the surface of the object so that subsurface scattering of radiation that penetrates the object from one fringe overlaps the subsurface scatter from the from the two neighboring fringes, and thus diffuses the fringes that propagate below the surface, such that as a result, the scattered subsurface radiation provides a substantially constant background to the image of the fringe pattern, at the photodetector array, of the fringes projected on the surface of the translucent object; detecting optical radiation scattered from the fringe pattern projected on the surface and scattered from below the surface; changing a phase of the optical radiation emitted from one of the optical sources (14A, 14B) relative to a phase of the optical radiation emitted from the other optical source (14A, 14B) 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, wherein the said background is ignored by a phase analysis of the apparent phase of the fringe pattern, or phase-shifted fringe pattern, wherein the apparent phase is the apparent location of the detected fringe pattern. illuminating a surface of a translucent object with optical radiation from a pair of optical sources (14A, 14B) to thereby project a fringe pattern on the surface, wherein the pair of optical sources comprises a master optical source to generate the optical radiation and a pair of optical fibers each in communication with the master optical source to receive the optical radiation and each having an exit end for emitting the optical radiation, the object having a wavelength-dependent transmittance characteristic and a wavelength-dependent reflectance characteristic, 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 constant background intensity with respect to the fringe pattern on the surface, the optical radiation from each optical source (14A, 14B) being coherent with respect to the optical radiation emitted from the other optical source (14A, 14B); controlling, including controlling the separation of the fiber exit ends, the spatial frequency of the fringe pattern to be a predetermined value at the surface of the object so that subsurface scattering of radiation that penetrates the object from one fringe overlaps the subsurface scatter from the from the two neighboring fringes, and thus diffuses the fringes that propagate below the surface, such that as a result, the scattered subsurface radiation provides a substantially constant background to the image of the fringe pattern, at the photodetector array, of the fringes projected on the surface of the translucent object; detecting optical radiation scattered from the fringe pattern projected on the surface and scattered from below the surface; changing a phase of the optical radiation emitted from one of the optical sources (14A, 14B) relative to a phase of the optical radiation emitted from the other optical source (14A, 14B) 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, wherein the said background is ignored by a phase analysis of the apparent phase of the fringe pattern, or phase-shifted fringe pattern, wherein the apparent phase is the apparent location of the detected fringe pattern.