Device for scanning a radiation-reflecting information surface with optical radiation
US4771411A · kind A · utility
13Cited by
2References
4Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 8, 1986 |
| Grant date | Sep 13, 1988 |
| Priority date | — |
| Expiry date | Dec 8, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0909
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical scanning device is described which comprises a radiation source (6), an objective system (8) and a diffraction grating (9) which is arranged between the objective system and the radiation source to separate the radiation beam (b') reflected by the information surface (2) to be scanned from the beam (b) emitted by the radiation source and for introducing astigmatism in the reflected beam (b') for the purpose of focus-error detection. In principle, the grating (9) has a constant grating period and is arranged at a small angle (.alpha.) in the beam (b').
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.