Patent ID: 7405832

Claim:
A wavefront interferometry system comprising: a source for generating a source beam; a reference object which interacts with at least a portion of the source beam to produce a reference beam; an optical system for deriving a measurement beam from the source beam and directing the measurement beam towards a measurement object to produce a return measurement beam that is combined with the reference beam to produce a combined beam; a beam splitter for separating out first and second portions of the combined beam; a first detector system for generating a first interference signal from the first portion of the combined beam; a second detector system for generating a second interference signal from the second portion of the combined beam; and a processor system programmed to concurrently process both the first and second interference signals to generate from the first interference signal a control signal and from the second interference signal information about the difference in wavefront profiles of the reference and measurement objects, wherein the control signal controls a system parameter so as to maintain an optical path length difference between a spot on the reference object and a corresponding spot on the measurement object at a constant value mod 2π.