Patent
1978-03-17
1979-10-16
Gellner, Michael L.
354 31, G03B 708
Patent
active
041711556
ABSTRACT:
The photographic apparatus has an objective and device for determining when the objective has focused an image in a predetermined plane. This device has an optical system having along its optical axis an image plane normal to the optical axis in which a given image is situated when the objective has properly focused an image corresponding to the given image in the above predetermined plane. The optical system has along its optical axis, spaced from the imaged plane, a detecting plane which is normal to the optical axis and the optical system includes in the detecting plane a pair of identical elongated photosensitive detecting units which respectively have optically equivalent positions with respect to the optical axis. Each of these units provides an output which varies as an image is moved longitudinally therealong. An optical structure in the form of two pairs of spaced prism means is situated along the optical axis between the image plane and the detecting plane for transmitting, when the given image is in the image plane, a pair of identical separate images, each of which is derived from the given image, respectively to identical positions along the pair of detecting units, and the optical structure displaces the identical images transmitted to the pair of detecting units respectively in opposite directions along the pair of detecting units as the given image is displaced with respect to the image plane so that the outputs can be compared to determine the location of the pair of images on the respective detecting means.
REFERENCES:
patent: 3596101 (1971-07-01), Someya et al.
patent: 4083056 (1978-04-01), Nakamura et al.
Jyojiki Masao
Nakamura Kazuo
Asahi Kogaku Kogyo Kabushiki Kaisha
Gellner Michael L.
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