INTERFEROMETRY EMPLOYING REFRACTIVE INDEX DISPERSION

摘要

An interferometry system includes: a light source, defining a coherence length, an interferometer configured to combine measurement and reference beams to form an output beam, where the interferometer includes a dispersion imbalance between measurement and reference paths large enough to produce a coherence envelope for the system having a width more than twice the coherence length; a phase modulation device configured to introduce a variable phase between the measurement and reference beams; a detector; imaging optics to direct the output beam to the detector and produce an image of the measurement surface; and an electronic processor electronically coupled to the phase modulation device and the detector and configured to record multiple interference signals corresponding to different locations on the measurement surface, in which the interference signals are based on the intensity of the output beam as a function of the variable phase for the different locations of the measurement surface.

主权项

1. An interferometry system comprising:
a light source configured to emit light over a range of wavelengths to define a coherence length; an interferometer configured to direct a measurement beam along a measurement path contacting a measurement surface of a measurement object, direct a reference beam along a reference path contacting a reference surface, and combine the measurement and reference beams to form an output beam after the measurement and reference beams contact the measurement and reference surfaces, respectively, wherein the measurement and reference beams are derived from the light source, and wherein the interferometer comprises a dispersion imbalance between the measurement and reference paths large enough to produce a coherence envelope for the interferometry system having a width more than twice the coherence length; a phase modulation device configured to introduce a variable phase between the measurement and reference beams; a detector; imaging optics to direct the output beam to the detector and produce an image of the measurement surface; an electronic processor electronically coupled to the phase modulation device and the detector and configured to record multiple interference signals corresponding to different locations on the measurement surface, wherein the interference signals are based on the intensity of the output beam as a function of the variable phase for the different locations of the measurement surface.