Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1990-11-26
1992-11-03
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
354408, G01J 120, G03B 300
Patent
active
051608340
ABSTRACT:
A focus detecting apparatus has a condenser lens provided near a primary image of an object formed through an objective lens, and a plurality of focus detecting optical systems, each detecting deviation between the relative positions of a pair of secondary images. Each focus detecting optical system has a pair of stop openings provided rearwardly of the condenser lens for dividing a marginal area of the exit pupil of the objective lens into a pair of divided pupil areas that are symmetrically disposed with respect to the optic axis of the objective lens. A pair of re-imaging lenses is disposed rearwardly of each pair of stop openings for forming a pair of secondary images. The directions of deviation of the pairs of secondary images differ from each other. The interval between the centers of the stop openings of each pair of stop openings is substantially the same for all the pairs of stop openings, but the radii of circles that circumscribe respective pairs of stop openings differ from each other.
REFERENCES:
patent: 4699493 (1987-10-01), Koyama et al.
patent: 4859842 (1989-08-01), Suda et al.
patent: 4967226 (1990-10-01), Kuwata
patent: 4992819 (1991-02-01), Ohtaka et al.
Messinger Michael
Nelms David C.
Nikon Corporation
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