Sound carrier amplitude measurement system
US4363118A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 22, 1980 |
| Grant date | Dec 7, 1982 |
| Priority date | — |
| Expiry date | Sep 22, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus provides an incident light beam which illuminates the surface of a grooved disc, having signal elements recorded therein in the form of a succession of spaced apart depressions, with a light spot that spans a plurality of convolutions of the groove. The structure of the groove convolutions and signal elements forms a two-dimensional diffraction grating which reflects light into a plurality of diffraction order beams. Photodetectors, respectively positioned to intercept several of the reflected beams provide outputs corresponding to the light power in the respective reflected beams. Estimations of signal element depth in the region illuminated by the light spot may be made from the measured light powers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.