Optical head
US5737297A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 1997 |
| Grant date | Apr 7, 1998 |
| Priority date | — |
| Expiry date | Feb 11, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1378
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A light radiated from a light source is divided by a grating into a main beam for detecting information signals and sub-beams for tracking, and thus irradiates a mini disk. The beams reflected by the mini disk are converged through a concave cylindrical mirror on a second light detector composed of adjacently disposed divided light receiving elements H (light receiving parts A and B) and J (light receiving parts C and D) and light receiving elements E1, F1, E2 and F2. The concave cylindrical mirror shapes the reflected beams so that spots of the reflected beams converged on the second light detector take elliptic shapes that are flattened in a direction in which the main beam for detecting the information signals and the sub-beams for tracking are arranged. In this manner, reliability of an optical head can be improved without increasing the size of the light receiving elements and without causing interference between a main spot and sub-spots.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.