Focus detecting device

Details Focus detecting device Focus detecting device

1974-12-12

1976-02-17

Smith, Alfred E.

Optics: measuring and testing

Lens or reflective image former testing

Focal length measuring

354 25, 356123, G03B 1318

Patent

active

039388948

ABSTRACT:
A photoelectric focus detecting member includes a semiconductor substrate of a first polarity and at least two closely transversely spaced parallel longitudinally extending photosensitive laminae of a polarity opposite to the first polarity to form corresponding photodiodes. Each of the photosensitive laminae is masked to provide regularly spaced light receiving areas alternating with masked areas, the light receiving areas of successive transversely spaced photodiodes being relatively longitudinally offset to present a checkered pattern. The detecting element is positioned in the focal plane of a lens and is either stationary or oscillated. The difference in potential between the diodes or the amplitude of the AC current in a circuit including the photodiodes is a function of the condition of focus of the lens.

REFERENCES:
patent: 3542475 (1970-11-01), Cooper
patent: 3714524 (1973-01-01), Katsuyama
patent: 3833806 (1974-09-01), Sato

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