Autofocusing control system
US4725721A · kind A · utility
36Cited by
6References
13Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 16, 1985 |
| Grant date | Feb 16, 1988 |
| Priority date | — |
| Expiry date | Aug 16, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1374
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An autofocusing control system makes a position of focusing spot follow for itself a displacement of an information medium. In the autofocusing control system, a single mode semiconductor laser is excited in a multi oscillation mode by returning part of a reflected light beam from the information medium, and a focusing lens having chromatic aberration is used which focuses a laser beam from the semiconductor laser onto a different position along the optical axis of the lens in association with a different laser wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.