Abstract: The invention contemplates a method and apparatus for automatically performing digital measurement of vertex dioptric powers in the principal planes of toric spectacle lenses. A spectacle lens is transilluminated by a parallel-ray bundle of monochromatic light which, after passage through the spectacle lens, is limited by an annular stop in the immediate vicinity of the vertex of the spectacle lens. A beamsplitter divides the light which passes through the spectacle lens into two individual light beams. As a result, an elliptical figure is projected to two planes, in each of which is located at least one self-scanning diode line.

Abstract: The invention contemplates a refractometer that images a test mark on the retina and is automatic in its determination of both refractive-power and astigmatism parameters, for the eye under examination. An imaging lens serves both (1) to project the test mark to the retina and (2) to convey that image for refocus external to the eye, to a scanner having the ability to digitally establish the eye's focal length. In the process of establishing the eye's focal length, the instrument automatically positions the imaging lens to best serve infinity viewing by the eye, and a prism then rotates the test mark while the scanner photoelectrically tracks the refocused image for the angles at which response is at a maximum, thus establishing astigmatism parameters. The instrument provides selective direct indication or print-out of the automatically determined parametric values.