Patent ID: 7064838

Claim:
An interferometry system for making interferometric measurements of an object, said system comprising: a source assembly that generates an input beam; a detector assembly that includes a detector element; and an interferometer that includes a source imaging system that focuses the input beam onto a spot on or in the object and an object imaging system that images the spot onto the detector element as an interference beam, said object imaging system combining light coming from the spot with a reference beam to produce the interference beam, wherein the source imaging system is characterized by a first aperture stop that defines a first aperture, said source imaging system including a first phase shifter that introduces a first phase shift in light passing through a first region of the first aperture relative to light passing through a second region of the first aperture, said second region of the first aperture being the region of the aperture that is outside of the first region of the first aperture, and wherein the object imaging system is characterized by a second aperture stop that defines a second aperture, said object imaging system including a second phase shifter that introduces a second phase shift in light passing through a first region of the second aperture relative to light passing through a second region of the second aperture, said second region of the second aperture being the region of the aperture that is outside of the first region of the second aperture.