Multi-bandwidth optical playback apparatus having minimum baseband distortion
US4477891A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 12, 1982 |
| Grant date | Oct 16, 1984 |
| Priority date | — |
| Expiry date | Mar 12, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/139
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical playback system is used to recover data recorded in an elongated information track, comprising undulations representative of the data, on a surface of a record medium. The data is recorded over two substantially different frequency bands, for example, a video signal may be recorded over a high frequency deviation range and a sound signal may be recorded over a low frequency deviation range. The optical playback system is provided with a dual response characteristic. The response of the system to the low frequency signals is improved by utilizing a properly oriented linearly polarized readout light beam for recovering the low frequency signals, by using a light source that provides a relatively short wavelength light beam, and by providing an input stop for varying the effective numerical aperture of the objective lens and an output stop which is matched to the shape of the input stop.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.