Patent Document ID: 7667852
Application ID: 12039185
Patent Flag: 1

Claim One:
1. A method for obtaining at least one of shape, thickness, and inhomogeneity of an object having first and second opposing surfaces, the method comprising: providing an interferometer comprising: a first reference surface; a second reference surface disposed substantially parallel to the first reference surface; and a cavity defined between the first reference surface and the second reference surface; receiving an object into the cavity such that the first surface of the object is facing the first reference surface and the second surface of the object is facing the second reference surface, where an optical path remains unobstructed by the object between the first reference surface and the second reference surface; directing a light into the interferometer through only the first reference surface, such that the light produces; a first reflected light that comprises a portion of the light that is reflected from the first reference surface, a second reflected light that comprises a portion of the light that is reflected from the second reference surface along the unobstructed optical path, a third reflected light that comprises a portion of the light that is reflected from the first surface of the object, and a fourth reflected light that comprises a portion of the light that is reflected from the second surface of the object; contemporaneously recording multiple interferograms generated by phase differences in the reflected lights; separating the contemporaneously recorded interferograms into individual interferograms, including; an A interferogram representing phase differences between the first and third reflected lights; a B interferogram representing phase differences between the second and fourth reflected lights; a T interferogram representing phase differences between the third and fourth reflected lights; and a C interferogram representing phase differences between the first and second reflected lights; computing a height of the first surface of the object from the phase differences of the A interferogram; computing a height of the second surface of the object from the phase differences of the B interferogram; computing a thickness of the object from subtracting a sum of the phase differences of the A interferogram and the phase differences of the B interferogram from the phase differences of the C interferogram; and computing a material inhomogeneity of the object by subtracting the phase differences of the C interferogram from the sum of the phase differences of the A interferogram, the phase differences of the B interferogram, and the phase differences of the T interferogram.