Apparatus for measuring the refractive errors of an eye

Claim 1

Apparatus for use by an examiner in measuring the refractive error of a patient''s eye, said apparatus comprising a target, means for illuminating said target with white light, axially movable lens means aligned with said target and positioned so as to focus upon said target and project a beam of substantially parallel light from said target along a predetermined projection path and into said eye when located at an eye-examination position of said apparatus, said lens means and the lens of the eye being examined jointly serving to form an image of said target at a focal plane within said eye and adjacent the retina thereof and such that the amount of axial movement of said lens means is a function of the refractive power of the eye being examined, light-dispersion means having at least a part thereof disposed in said path between said lens means and said eyeexamination position for so laterally dispersing the component wavelengths of the light forming the image of said target at said focal plane as to be unrecognizable by said patient, and beamsplitting means so positioned and arranged in said projection path between said lens means and said eye-examination position as to receive component wavelengths of dispersed light reflected by said retina back along said projection path and to direct a part thereof along a different path to an observation position, said light-dispersion means being positioned so as to recombine the reflected dispersed light before it reaches said observation position.