Optical focussing sensor
US4079248A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1976 |
| Grant date | Mar 14, 1978 |
| Priority date | — |
| Expiry date | Sep 24, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0917
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The invention relates to focussing sensors for measuring the deviation between the point of convergence of a beam of radiant energy and the surface of an object receiving this beam. According to the invention, a degree of asymmetry is first introduced into this beam, after which the image of this convergence point if formed on photoelectric sensors enabling the distortions of this image to be measured. These sensors supply signals which are dependent upon said deviation and enable it to be measured. This invention relates to optical focussing sensors by which it is possible to measure the focussing deviation of a beam of radiant energy of which the point of convergence has to be kept in coincidence with the surface of an object which it is desired to illuminate by a spot. An optical sensor of this type may be used in the production of an optical reader intended to read for example the video information recorded in the form of lines of variable length and spacing forming a track on the surface of a support such as a disc. On account of the high density of information thus recorded, the elements characteristic of the information are extremely small and, in addition, it is necessary f…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.