Focusing state monitoring apparatus in optical recording apparatus
US4521876A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 16, 1980 |
| Grant date | Jun 4, 1985 |
| Priority date | — |
| Expiry date | Oct 16, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/085
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A monitoring apparatus is used in an optical recording apparatus which performs the recording by respectively forming a first beam spot and a second beam spot by focusing light beam portions respectively having diameters smaller than that of first light beam and second light beam respectively modulated by first signal and second signal on a recording medium by use of focusing lens. The monitoring apparatus comprises an enlarging and imaging optical system for enlarging and imaging reflected beams of the first and second beam spots from the recording medium, by obtaining the reflected beams outside optical paths of the first and second light beams, reflecting optical system for reflecting the first and second light beams at an optical path leading to the focusing lens for focusing the first and second light beams by use of an optical member, and supplying the reflected first and second light beams to the enlarging and imaging optical system as incident light, and monitoring optical system for monitoring images imaged by the enlarging and imaging optical system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.