The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 17, 1993
Filed:
Sep. 23, 1991
Eiichi Sano, Tokyo, JP;
Kabushiki Kaisha Topcon, Tokyo, JP;
Abstract
The ophthalmic photographic apparatus of the invention comprises a means of detecting abnormalities in the filters used when a fluorescent agent is caused to fluoresce by infra-red light in order to photograph a subject's eye. According to the ophthalmic photographic apparatus of the invention, the abnormality-detecting means detects an abnormality if there is a flaw or deterioration of a filter used to take a photograph when a fluorescent agent is caused to fluoresce by infra-red light. The abnormality-detecting means preferably detects abnormalities of an exciter filter which transmits infra-red light in a specific wavelength range which causes fluorescence of a fluorescent agent in an illuminating optical system having an illuminating light source. More specifically, this abnormality-detecting means comprises a reflecting mirror, disposed on the opposite side of the exciter filter to the illuminating light source, which reflects a part of the illuminating light (here, the term illuminating light will be understood to mean infra-red light in the specific wavelength range and illuminating light in other wavelength ranges) that has passed through the exciter filter; a photodetector disposed in the direction of reflection of the reflecting mirror which detects illuminating light reflected by the mirror; and a discriminating circuit which determines whether or not there is an abnormality in the exciter filter according to the output variation of the photodetector.