Dynamic phase-shift interferometer utilizing a synchronous optical frequency-shift
US12216051B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 21, 2022 |
| Grant date | Feb 4, 2025 |
| Priority date | — |
| Expiry date | Jan 21, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/06113
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical metrology device characterizes a test object using a phase shift interferometer with synchronous time varying optical frequency shifts. A light source generates a beam having a time varying frequency, which is divided into two collinear, orthogonally polarized beams that differ by a first frequency shift. One or more optical cavities receive the beams and produce a pair of reference beams that differ from each other in frequency by the first frequency shift and a pair of test beams with a second frequency shift induced by the one or more optical cavities. The test beams differ from each other by the first frequency shift and differ from the reference beams by the second frequency shift. The first frequency shift has a pre-defined relationship with respect to the second frequency shift to generate interference between a reference beam and test beam that have frequency shift magnitudes with the pre-defined relationship.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.