Position measuring apparatus utilizing two-beam interferences to create phase displaced signals
US5120132A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1990 |
| Grant date | Jun 9, 1992 |
| Priority date | — |
| Expiry date | Nov 1, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A phase grating is provided in this length or angle measuring apparatus, which operates by interference. A beam striking the phase grating from a laser is diffracted into .+-.1st order beams at the phase grating. The diffracted .+-.1st order beams are reflected at retroreflecting elements and, diffracted once again at the phase grating, and made to interfere in pairs. The modulations in intensity of the two-beam interferences are converted by detectors into electrical signals that are phase-displaced from one another. The diffraction grating is configured such that at least one partial beam cluster of the zero order of diffraction is involved in the formation of at least one of the two-beam interferences.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.