Device for use with a cornea shape measuring apparatus

Details Device for use with a cornea shape measuring apparatus Device for use with a cornea shape measuring apparatus

1989-11-01

1991-03-12

Bovernick, Rodney B.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Objective type

351211, A61B 310

Patent

active

049990098

ABSTRACT:
The corneal reflection virtual image of an index mark for cornea shape measurement is displaced by a variation in the working distance, but a light beam regulating device for extracting the corneal reflection light whose principal light ray is a light ray corresponding to the direction of displacement thereof is provided at a particular position in a cornea shape measuring optical system to thereby eliminate any measurement error based on the variation in the working distance. When a different region of the cornea is to be measured with the index mark displaced in the direction of the optic axis, a predetermined principal light ray conforming to the position of the index mark in the direction of the optic axis is caused to enter the light beam regulating device.

REFERENCES:
patent: 4660946 (1987-04-01), Nakamura et al.
patent: 4660947 (1987-04-01), Amoils
patent: 4764006 (1988-08-01), Hamano et al.

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