Abstract: A method and apparatus are disclosed for controlling the refractive state of the eye. The image of a visual target is continuously positioned close to, but offset from, the retinal plane of the eye to be controlled. The offset is in such a direction from the retina that as the eye attempts to focus on the image, the refractive state of the eye will change toward the desired goal. To increase the effectiveness of the method and apparatus, the position of the image is continually varied along the optical axis.

Abstract: Apparatus for measuring the refractive properties of a sphero-cylindrical lens system of the type utilizing an incident light beam scanned in at a predetermined radius about the central axis of the lens system to provide a refracted beam. A generally opaque mask having an annular transparent portion is positioned in the path of the refracted beam, to eliminate errors caused by deviations in radial height from the scanning radius of the refracted beam as it exits the lens system due to refraction within the interior of the optical system. A position-sensitive photodetector generates a signal indicative of the instantaneous position in a given plane due to refraction of the portions of the light beam passing through the mask. The photodetector output signal is then processed to provide an indication of the refractive properties. Various embodiments of the mask are also disclosed. Also permutations of the above including pinhole aperture, input light and other detection means is discussed.

Abstract: Apparatus for measuring the refractive properties of an optical system of the type utilizing a light beam scanned in a circle or predetermined radius about the central axis of the optical system to provide a refracted beam. A generally opaque mask having specially configured annular transparent portions positioned in the path of the refracted beam to eliminate errors caused by deviations in radial height from the scanning radius of the refracted beam as it exits the optical system due to refraction within the interior of the optical system. A position-sensitive photodetector generates a signal indicative of the instantaneous position in a given plane due to refraction of the portion of the light beam passing through the mask. The photodetector output signal is then processed to provide an indication of the refractive properties.

Abstract: Apparatus and method is disclosed for measuring refractive properties such as spherical power, cylindrical power, cylindrical axis, etc., which are potentially present in a sphero-cylindrical optical system. Relative movement is effected between an incident light beam and the optical system under test so as to cause the incident beam to effectively move about a pre-defined first locus in the plane of the optical system thereby producing a refracted light beam which moves correspondingly about a second locus in a subsequent plane parallel to the plane of the optical system.