Apparatus for determining photoelectrically the position of at least one focusing plane of an image
US4037958A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1975 |
| Grant date | Jul 26, 1977 |
| Priority date | — |
| Expiry date | Oct 15, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/30
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Apparatus for the photoelectrical determination of the position of at least one focusing plane of an image comprising an imaging optics, at least one spatial frequency filter in the form of a structure or grating mounted in the vicinity of one image plane of said imaging optics, a photoelectric receiver system associated with the filter containing at least one detector and receiving light fluxes leaving this filter, at least one means for generating a relative motion between the structure or grating and the object image, and means for analyzing the output signals from the photoelectric receiver system for distance display and/or focusing of the apparatus. The apparatus is improved by having the imaging optics (10) preceded by wo rhombic prisms (19, 20) so that each pupil half obtains its light through one of the two prisms. A reference beam is provided to show and/or eliminate mechanical changes in the apparatus effecting faultiness of the measuring result.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.