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Abstract

An auto-refractometer according to this invention comprises a light beam source for producing a measuring ray wherein beams from a pair of invisible infrared ray emission diodes are alternately flickered, and real images of the beams are converged on respective sides of ridges at the output side of a V-shape coincidence prism at positions close to the ray axis thereby reducing the horizontal distance between the beams. A measuring optical system includes a transmitting collimater which projects said measuring ray passing through a vertical slit to permit focusing of a slit image on the retina. A receiving collimator collects beams reflected from the cornea and the retina, and by a semi-transparent mirror, and directs them via a reflection mirror to an interference bar which interferes with the beam from the cornea. A split prism divides the beam received from the retina, and a pair of elements photo-electrically convert the divided beam into electrical outputs. An electrical circuit includes a movable mechanism integrally associated with a lens system to focusing the image reflected from the retina on said split prism. The circuit produces high-speed flickering of the infrared ray emission diodes and responds to differential outputs from the photo-electric elements to cause said movable mechanism to move by an amount corresponding to the refractory diopter of the eye.

Other References

• Allen et al., "An Infra-Red...Mechanism," Amer. J. Opt. & Such Amer. Acad. Opt., vol. 37, pp. 403-407, 1960
• Roth, "Automatic...Eye," Review of Sci. Inst., vol. 36, No. 11, pp. 1636-1639, Nov. 1965
• Warshawsky, "High...Accomodation," JOSA, vol. 54, No. 3, Mar. 1964, pp. 375-379
• Campbell et al., "High...Optometer," JOSA, vol. 49, No. 3, Mar. 1959, pp. 268-272