Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1995-06-21
1997-07-29
Allen, Stephone
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250204, 396111, G01J 120, G03B 1336
Patent
active
056524242
ABSTRACT:
A focus state detection device includes a field mask aperture having a shape created from the overlapping portions of two areas. The first area is formed by the outermost perimeter of the cross-section of light rays passing through the field mask plane toward each of the arrays of photoelectric conversion devices from each of point of the conjugal images of the arrays of photoelectric conversion devices at the primary imaging plane. The second area is formed by line segments that are the projection onto the field mask plane of the boundary lines at the surface of each re-imaging lens on the side toward the arrays of photoelectric conversion devices. The use of this shape causes light to be directed within the boundary lines of the outer perimeter of each of the re-imaging lenses. Through the use of this shape, the creation of stray light and internal reflection in the focus state detection optical system are suppressed, and stable focus state detection precision is enabled.
REFERENCES:
patent: 4857718 (1989-08-01), Karasaki et al.
patent: 4859842 (1989-08-01), Suda et al.
patent: 5530513 (1996-06-01), Ohsawa
Allen Stephone
Nikon Corporation
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