Abstract: A method and apparatus for measuring eye refraction errors in which a plurality of infrared patterns are projected onto an eye to be measured. The reflected light is directed onto corresponding light sensitive detectors the outputs of which are coupled through bandpass filters, an automatic gain control circuit and an A/D converter to a microprocessor. The microprocessor analyses the digitized outputs calculating refraction powers in accordance with a disclosed nonlinear regression technique. The refraction errors of the eye, along with a reliability coefficient, are calculated in accordance with the thusly determined refraction powers.

Abstract: A scale board carries a scale having a predetermined pitch and a light source projects this scale onto an array of sensors having a pitch which is substantially but not exactly equal to the pitch of the scale. By comparing successive pairs of sensor outputs, the angular position of the scale board can be determined to a resolution much smaller than the scale pitch.

Abstract: An opthalmological instrument including a blinking detecting device for positively detecting when an eye is blinking to thereby eliminate errors in optical measurements due to variations in the signal light produced by the blinking. An optical system receives light beams reflected from a portion of an eye under examination to form an image of the front portion of the eye in an image plane. An image pickup element is disposed at the image plane and produces an output video signal in response thereto. A detecting circuit which receives the video signal determines whether or not the image pickup element exceeds a predetermined threshold value. If the threshold value is not exceeded, an indication is produced that blinking has occurred.

Abstract: A device for measuring the refractive error of an eye in which refractive powers in a plurality of longitudinal directions are simultaneously measured with a high S-N ratio with a high accuracy. A movable chart is provided in a predetermined direction in a plane perpendicular to an optical axis of an optical system which projects the image of the chart onto the retina of the eye being examined. Measuring means measures the refractive error of the eye in accordance with the state of the optical system at the position thereof at which the image projected onto the retina is in focus. The chart has plural striped patterns which are oriented at different angles from one another.

Abstract: A focal plane detecting device is disclosed which uses an optical fiber system located within a rotating motor shaft or the like to scan an image plane and to deliver the scanned light to a stationary means, such as a photoconductor for developing a contrast signal. The optical system includes at least one optical fiber having its light incident end a fixed distance away from the axis of rotation of the shaft, but facing in the axial direction so as to scan a circular-like pattern of the plane wherein the light incident surface exists. The optical fiber extends through the shaft and exits in such a manner as to direct light therefrom upon a light detector at least part of the time that the shaft is rotating. Preferably the optical system includes a pair of optical fibers each having light incident ends symmetrically about the axis of rotation of the shaft and separated by a distance of .DELTA.Z along the axis of rotation.