Laser recording apparatus with off-center lens and error detection
US4623784A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1984 |
| Grant date | Nov 18, 1986 |
| Priority date | — |
| Expiry date | Dec 20, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/36
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A laser recording apparatus for optically recording information on a medium. A laser radiates a beam through an off-center lens. The lens deflects and focusses the beam onto a recording medium at a slight angle. The reflected beam returns through the lens on the opposite side of the optic axis from the incident beam. A mirror in the optical path directs the beam to a photodetector. The apparatus has broadband capabilities and is particularly useful at eliminating unwanted optical feedback when recording onto media having a birefringent protecting layer. Recording errors due to dirt and scratches may be detected by a second embodiment that has two lasers emitting light of different frequencies which upon reflection are detected and compared.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.