Synchronous frequency-shift mechanism in Fizeau interferometer
US7675628B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 7, 2007 |
| Grant date | Mar 9, 2010 |
| Priority date | — |
| Expiry date | Aug 20, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical device for characterizing a test surface combines a Fizeau interferometer with a polarization frequency-shifting element. Two substantially collinear, orthogonally polarized beams having respective frequencies differing by a predetermined frequency shift are generated by the polarization frequency-shifting element and projected into the Fizeau optical cavity to produce a pair of test beams and a pair of reference beams, wherein the beams in each pair have orthogonal polarization states and have frequencies differing by the predetermined frequency shift. A second, substantially equal frequency shift is introduced in the Fizeau cavity on either one of the pairs of test and reference beams, thereby generating a four-beam collinear output that produces an interferogram without tilt or short-coherence light. The invention may also be implemented by reversing the order of the Fizeau cavity and the polarization frequency-shifting element in the optical train.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.