Patent ID: 7019840
Filing Date: 2006-03-28
Classification: G01B,G11B

Abstract:
1. An optical interferometer for measuring the surface profile of a smooth, reflective surface, comprising: a light source for generating a light beam in a first polarization state; a first beam splitter for receiving the light beam and for dividing the light beam into original first and second beams of substantially equal intensity; a half wave plate for receiving the original second beam from the first beam splitter, and converting the second light beam to a different polarization state; a polarizing cube beam splitter for receiving and transmitting the original first light beam to the reflective surface at a first point, and for receiving and reflecting the original second light beam to the reflective surface at a second point such that the original first and second light beams are received at the reflective surface an offset distance apart, and such that the original first and second light beams are reflected back to the first beam splitter where they are split and then recombined into new first and second light beams; and a photodiode for receiving the new second light beam, the new second light beam being constructed by the interference of the half intensity of the original first and the half intensity of the original second light beams, and the photodiode generating signals in response to the changing interference fringes caused as a result of the modulation of the optical path length difference between the original first and second beams so that a local height difference on the reflective surface between the first and second surface points may be determined.