Focus detection apparatus
US4916473A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 1988 |
| Grant date | Apr 10, 1990 |
| Priority date | — |
| Expiry date | Sep 27, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/34
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus detection apparatus for a camera comprising: a condensor lens being arranged close to or behind a predetermined focal plane of an objective lens of the camera. A pair of image separation members for separating the image of an object formed on the predetermined focal plane by use of light having been passed through said objective lens into two images which are arranged behind the condensor lens symmetrically with respect to the optical axis of the objective lens, wherein the correlation between the two images formed separately is measured in order to detect the focus condition of the objective lens; said image separating members including a mask members for projecting the exit pupil of the image separation members within an exit pupil of a cata-dioptric lens system as the objective lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.