Phase grating, its fabricating method, optical encoder, motor using the optical encoder, and robot using the motor
US5754341A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Jun 10, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase grating has a concave part of rectangular shape type substantially, of which grating depth is deeper in a specific range than depth d' calculated in a formula EQU .vertline.n-n.sub.0 .vertline..times.(p-d'/e)/p.times.d'=(.lambda./2).times.(1+2m) (where m=0, .+-.1, .+-.2, . . . ) in terms of center wavelength .lambda. of light having partial interference to be diffracted by the phase grating, pitch length p of the phase grating, refractive index n of base material of the phase grating, refractive index n.sub.0 of medium surrounding the phase grating, and shape ratio e as the ratio of grating depth to width of slope of the concave part.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.