Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Patent
1991-09-23
1993-08-17
Bovernick, Rodney B.
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
351206, 351233, 354 62, A61B 310
Patent
active
052373509
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.
REFERENCES:
patent: 4799783 (1989-01-01), Takahashi et al.
patent: 5118179 (1992-06-01), Sano et al.
patent: 5152295 (1992-10-01), Kobayashi et al.
Bovernick Rodney B.
Dang Hung Xuan
Kabushiki Kaisha Topcon
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