Optical encoding apparatus for measuring displacement of an object using diffraction gratings and twice-diffracted and twice-transmitted light
US5574558A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1995 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | May 19, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical encoding apparatus is provided which is not affected by fluctuation of wavelength of a light beam due to temperature change, without sacrificing resolution of measurement. The optical encoding apparatus includes a light source for emitting a light beam, a light beam condenser for condensing the light beam emitted by the light source, a first diffraction grating to which light beams condensed by the light beam condenser are directed, and a second diffraction grating to which light beams exiting from the first diffraction grating are directed. Additionally, a displacement information obtaining device is included for obtaining information regarding a displacement of one of the first and second diffraction gratings, the information being obtained according to a twice-diffracted beam and a twice-transmitted beam incident upon the second diffraction grating. The twice-diffracted beam is diffracted by the first diffraction grating, and the twice-transmitted beam is transmitted through the first diffraction grating.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.