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: 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 hand-held lens meter including first and second optical systems mounted in a substantially Y-shaped hand-holdable body is disclosed. The first optical system includes a target, a lens rest and an objective lens. The target is slidably mounted in a grip portion of the lens meter body while the two optical systems are mounted in the upper legs thereof. The second optical system includes a relay lens, a focusing screen, an eyepiece lens and first and second reflecting surfaces which may be consituted either by first and second mirrors or a pentagonal prism. A prism is provided preferably as the reflecting surface of the first optical system with the prism having an optical path length longer than the outside diameter of the objective lens. The target is slidably moved along the optical axis in response to rotation of a power-measuring dial which is calibrated in terms of the powers of lenses to be measured.

Abstract: An automatic lens meter for measuring a pherical power, a cylinder power, an angle of cylinder axis, and a power of prism of an ophthalmic lens. The automatic lens meter is characterized by the use of a shading device to obtain the coordinates of the points at which respective light rays emitted from respective pin-holes of a multiple-pin-hole disc cross the second focal plane of an objective lens, according to a shading time lag among respective light rays.