Interferometric encoder systems
US8300233B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 2011 |
| Grant date | Oct 30, 2012 |
| Priority date | — |
| Expiry date | Apr 14, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.