Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1975-10-31
1977-01-11
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250204, 250209, 354 25, G01J 120
Patent
active
040028992
ABSTRACT:
A focus detecting system includes first and second auxiliary optical devices for forming first and second auxiliary images of an object on first and second detector devices, respectively, which in some illustrated embodiments are closely disposed on a single substrate. Each detector device includes a plurality of linearly displaced light responsive elements, each element in the first detector device having a corresponding element in the second detector device in relatively the same position with respect to the detector devices. One of the optical devices moves with respect to its associated detector device to shift the light distribution pattern of the corresponding auxiliary image in the direction of the linear displacement of the light responsive elements. The moving optical device is so coupled to a moving objective lens, which focusses a principal image of the object on a light sensitive film, that when the principal image is in focus, equal amounts of light will fall on corresponding light responsive elements of the first and second detector devices. A signal processing circuit is connected to the light responsive elements to provide an output signal indicative of the relative identity of illumination intensity between corresponding light responsive elements, and therefore also indicative of the degree of focus of the principal image. This output signal is used to place the moving optical device and objective lens at the positions which give the best positional correspondence of the auxiliary image light distribution patterns on the detector devices, and hence the best focus of the principal image on the film.
REFERENCES:
patent: 3450883 (1969-06-01), Thomas
patent: 3493764 (1970-02-01), Craig
patent: 3610934 (1971-10-01), Turner
patent: 3684374 (1972-08-01), Humphrey
patent: 3844658 (1974-10-01), Gela et al.
Fairbairn David R.
Hanson Henry L.
Honeywell Inc.
Nelms David C.
Ungemach Charles J.
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