Optical information system to detect reflection of pit depth by evanescent wave
US5602819A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 18, 1995 |
| Grant date | Feb 11, 1997 |
| Priority date | — |
| Expiry date | Jul 18, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B13/04
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The information recording and reproducing apparatus includes: a recording medium including a plurality of concavo-convex pits; a light source for emitting laser light; a section for changing an optical characteristic value of the laser light, using interaction between the laser light and the recording medium; and a light detector for detecting the optical characteristic value of the laser light after the interaction occurs, and then outputting a signal in response to the detected optical characteristic value. The section for changing the optical characteristic value includes an evanescent wave generating section for generating an evanescent wave from the laser light. The evanescent wave generating section changes the optical characteristic value in accordance with how much the concavo-convex pits of the recording medium influences the evanescent wave. Multivalued data is reproduced on the basis of the signal from the light detector. The multivalued data corresponds to the dimension of the concavo-convex pits measured along the direction normal to the recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.