Photometering apparatus having a split light receiving device

Details Photometering apparatus having a split light receiving device Photometering apparatus having a split light receiving device

1994-05-27

1996-03-05

Pham, Hoa Q.

Optics: measuring and testing

Photometers

Photoelectric

356225, G01J 142

Patent

active

054972299

ABSTRACT:
A photometering apparatus for measuring the brightness of an object to be photographed, includes a condenser lens having at least one aspheric lens surface for condensing a bundle of rays reflected from the object. A diaphragm is provided at a predetermined distance behind the condenser lens with respect to the object, and a split type light receiving device is provided behind the diaphragm to receive light which passes through the diaphragm. These elements satisfy the condition represented by the formula 0.3.ltoreq.L.sub.ASP /T.sub.L .ltoreq.0.7, wherein "T" represents the distance between the surface of the condenser lens nearer to the object to be photographed and the light receiving device, and wherein "L.sub.ASP " represents the reduced distance between the aspheric surface of the condenser lens and the diaphragm. The term "L.sub.ASP " is defined by the relationship L.sub.ASP =(d.sub.L /N)+d.sub.s, wherein "d.sub.L " represents the thickness of the lens, "d.sub.s " the distance between the diaphragm and the surface of the lens nearer to the image, and "N" the refractive index of the lens at the e-line.

REFERENCES:
patent: 1990361 (1935-02-01), Bailey, Jr.
patent: 3134021 (1964-05-01), Ploke
patent: 3272104 (1966-09-01), Lytton
patent: 3478663 (1969-11-01), Tsuruoka et al.
patent: 3902792 (1975-09-01), Plummer
patent: 4005444 (1977-01-01), Uchiyama et al.
patent: 4437746 (1984-03-01), Ikemori
patent: 4542961 (1985-09-01), Sato
patent: 4676607 (1987-06-01), Wakamiya
patent: 5021818 (1991-06-01), Satoh et al.
patent: 5114225 (1992-05-01), Ogawa
patent: 5289225 (1994-02-01), Hirai

Affiliated with

Also associated with

Rating

Photometering apparatus having a split light receiving device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Photometering apparatus having a split light receiving device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photometering apparatus having a split light receiving device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1416222