Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Patent
1998-03-02
2000-06-27
Manuel, George
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
351211, A61B 314
Patent
active
060798289
ABSTRACT:
An ophthalmic measurement apparatus for observing or measuring an eye to be examined by positioning the apparatus so as to have a predetermined positional relationship with the eye, the ophthalmic measurement apparatus comprising an alignment target projecting device for projecting an alignment target onto a cornea of the eye, an alignment device provided with a photographing optical system for photographing an image of the projected alignment target by photoelectric imaging elements to perform an alignment based on condition of the alignment target image photographed by the photoelectric imaging elements, a measurement target projecting device for projecting a target for measurement onto the cornea of the eye, a measurement device for measuring a corneal shape of the eye based on an image of the projected target for measurement photographed by the photoelectric imaging elements, a focal depth varying device for making a focal depth of the image photographed by the photoelectric imaging elements variable and a changeover device for switching the focal depth, which is made to be variable by the focal depth varying device, upon the alignment and upon the measurement.
REFERENCES:
patent: 4917458 (1990-04-01), Matsumura
patent: 5000181 (1991-03-01), Katsuragi
patent: 5432596 (1995-07-01), Hayashi
patent: 5463430 (1995-10-01), Isogai et al.
patent: 5500697 (1996-03-01), Fujieda
patent: 5585872 (1996-12-01), Kohayakawa
Manuel George
Nidek Co. Ltd.
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