Optics: measuring and testing – Lens or reflective image former testing – Focal length measuring
Patent
1994-05-16
1996-11-12
Pham, Hoa Q.
Optics: measuring and testing
Lens or reflective image former testing
Focal length measuring
2502012, 396 89, G01B 900
Patent
active
055745555
ABSTRACT:
A lens inspection device has an objective lens composed by front and rear lenses, a two-dimensional image sensor and an image forming lens for forming a point image of light passing through the objective lens. A lens to be inspected is disposed between a light source and an object focal point of the objective lens. The light source projects a light beam through the lens to be inspected parallel to the optical axis of the objective lens, and the front lens of the objective lens is moved along the optical axis so as to shift the object focal point of the objective lens stepwise into a plurality of positions within a predetermined range including a normal focal point of the lens to be inspected. Brightness data of a point image formed on the two-dimensional image sensor is detected for each shifted position of the objective lens, and is used for judgment as to whether an actual focal point of the lens to be inspected is within a proper range. The location of the point of maximum brightness is also detected, so as to determine whether the inspected lens is misaligned as mounted in a camera or in a lens-fitted photographic film unit.
REFERENCES:
patent: 3493764 (1970-02-01), Craig
patent: 3782829 (1974-01-01), Herriott
patent: 4282548 (1981-08-01), Plummer
patent: 4435079 (1984-03-01), Hennick
patent: 5003165 (1991-03-01), Sarfati et al.
patent: 5017005 (1991-05-01), Shindo
Tagi Masahiro
Yamaguchi Yukihiko
Fuji Photo Film Co. , Ltd.
Pham Hoa Q.
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