Focus detecting system using a beam splitter to form an image at nominal best focus, slightly in front of best focus and slightly behind best focus
US5552594A · kind A · utility
4Cited by
9References
4Claims
0Family size
Assignee
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Key dates
| Filing date | Feb 14, 1995 |
| Grant date | Sep 3, 1996 |
| Priority date | — |
| Expiry date | Feb 14, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/38
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus detecting system for detecting focus state of an image forming optical system relative to an object, includes a beam splitter assembly for forming at least three coplanar two-dimensional images of a scene, each image having a different focus setting. An area array image sensor senses the images at the image forming plane. Signal processing electronics determine the sharpness of the three images and calculates an optimum focus setting for the optical system by deterring the variances of the three images and calculating a position of maximum variance corresponding to a best focus setting of the optical system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.