Position detector for detecting the position of an object using a diffraction grating positioned at an angle
US5369486A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 21, 1992 |
| Grant date | Nov 29, 1994 |
| Priority date | — |
| Expiry date | Sep 21, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A position detector includes a diffraction grating provided on the surface of an object, an illumination system for illuminating the diffraction grating, a detection system for detecting diffracted light diffracted from the diffraction grating, and a processing system for detecting positional information relating to the object. The illumination system emits a first pair of beams which are diffracted by the diffraction grating and interfere with each other, and emits a second pair of beams which are diffracted by the diffraction grating and also interfere with each other. The first pair of beams are incident upon the diffraction grating along a plane extending in a first direction in which the diffraction grating extends. The second pair of beams are incident upon the diffraction grating along a plane extending in a second direction in which the diffraction grating extends. The first and second directions are different from a grating line direction. The detection system detects the interfering light and generates first and second beat signals therefrom. The processing system detects positional information with respect to the first direction from the phase state of the first beat sig…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.