Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Folding
Patent
1977-06-02
1979-07-31
Sacher, Paul A.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Folding
350234, 351 13, 351 16, 354 62, A61B 314
Patent
active
041628276
ABSTRACT:
An ophthalmoscopic camera with an achromatic objective arranged on a common optical axis of an image forming lens in front of a photographic film and adapted to project a ring-shaped bundle of illuminating light rays onto the cornea of an eye to be photographed as the illuminating light rays come from a light source through a relay lens after reflection from an apertured mirror positioned between the objective and the image forming lens at an angle with the optical axis thereof. For an increase in the angle of view, the objective is constructed in the form of a biconvex triplet consisting of a forwardly convex negative meniscus lens, an equiconvex lens and a rearwardly convex negative meniscus lens with its four refracting surfaces so configured and so separated that a beam of image forming rays passing through a central aperture of the illuminating mirror to the film can be made free from disturbing light reflections from these four lens surfaces by use of a single black spot positioned at a point between the light source and the mirror in coaxial relation thereto.
REFERENCES:
patent: 1293086 (1919-02-01), Graf
patent: 3536379 (1970-10-01), Knetsch
patent: 3914032 (1975-10-01), Takano et al.
Canon Kabushiki Kaisha
Sacher Paul A.
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