Abstract: A plurality of light sources are caused to impinge in predetermined directions onto an optical system to be inspected. The reflected beams from the optical system are received by two or more pairs of photoelectric converting elements and the radius of curvature of the above mentioned optical system is measured on the basis of the phase difference of the output signals between the photoelectric converting elements forming the respective pairs. The reflected beams are first converted into a slit shaped series of beams, the angle of inclination of each of which, to which to the scanning direction, is made in two or more different known angles. An output device emitting the discriminating signal of the angle of inclination of the beams is provided and the discriminating signal and phase difference inputted to an operating circuit to obtain a refractive power.

Abstract: An optical system to be inspected is scanned with slit-shaped illuminating beams. The beams from the optical system are received with two or more pairs of photoelectric converting elements and the refractive power of the above mentioned optical system is measured on the basis of the phase difference of the output signals between the photoelectric converting elements forming the respective pairs. The angle of inclination of the slit-shaped illuminating beams to the scanning direction is made in two or more different known angles. An output device omitting the discriminating signal of the angle of inclination of the illuminating beams is provided and the discriminating signal and phase difference inputted to an operating circuit to obtain a refractive power.

Abstract: A method of measuring the radius of curvature of an object to be examined has a first procedure of projecting two pairs of light spots onto the object from different directions, a second procedure of obtaining by an imaging optical system the reflected images of the two pairs of light spots reflected by the object, and a third procedure of measuring the radius of curvature of the object from the positional relation between the reflected images by the imaging optical system.

Abstract: An automatic lens meter includes a first positive lens system, a second positive lens system having its forward focal plane coincident with the rearward focal plane of the first positive lens system, a pin-hole plate disposed in the forward focal plane of the second positive lens system, the optical axis of the first and second positive lens systems passing through the pin-hole of the pin-hole plate, four spot light source means disposed on the forward focus side of the first positive lens system, the four spot light source means being provided in a plane orthogonal to the optical axis and made conjugate with a predetermined position on the rearward focus side of the second positive lens system by the first and second positive lens systems, a lens to be examined being disposed at said predetermined position, a third positive lens system provided on the side opposite to the second positive lens system with respect to said predetermined position, light-receiving means disposed on the opposite side of the second

Abstract: An apparatus for subjectively measuring the refractive power of an eye includes obliquely disposed beam splitter means, diaphragm means provided on the reflection optical axis of the beam splitter means and having a pair of openings symmetric with the reflection optical axis, collimation mark means provided on the reflection optical axis of the beam splitter means and on the side opposite to the beam splitter means, first imaging lens means provided between the beam splitter means and the diaphragm means, second imaging lens means provided between the diaphragm means and the collimation mark means, rotating means for rotating an image of the openings of the diaphragm means about the reflection optical axis, means for varying the optical distance of the collimation mark means relative to the diaphragm means, first converter means for causing the angle of rotation of the rotating means to correspond to the direction of the astigmatism axis, and second converter means for causing the optical distance between the

Abstract: An apparatus in which an optical system to be examined is periodically scanned by a slit-like illuminating light beam and the light beam from the optical system is received by two pairs of photoelectric converters and the refractive power of the optical system is measured on the basis of the phase difference between the output signals of the photoelectric converters forming each of said pairs includes projection means capable of alternatively scanning the illuminating light beam from two known directions, output means adapted to put out a discrimination signal of the scanning direction of the illuminating light beam, and operational means for receiving the discrimination signal and the phase difference as inputs and obtaining a refractive power.

Abstract: In an eye fundus observation apparatus wherein light-intercepting members for eliminating flare are provided at predetermined positions in an illumination optical path which are substantially conjugate with the cornea and the front surface of the crystalline lens of an eye being examined in a condition in which the apparatus is focused to the fundus of the eye, an observation opening is formed at a position substantially conjugate with a position between the cornea and the front surface of the crystalline lens of the eye whereat the magnification of the reflected image on the rear surface of the crystalline lens is approximately one-to-one magnification in a condition in which the apparatus is focused to the fundus of the eye.

Abstract: An automatic focusing device in a stereoscopic microscope having a pair of left and right stereoscopic observation optical systems disposed rearwardly of a common objective lens includes automatic focusing means for converting an amount of focus deviation into an electrical signal and automatically controlling the stereoscopic microscope to its in-focus position on the basis of the electrical signal, and selector means for selecting the operation and non-operation of the automatic focusing means.

Abstract: Improvements in an eye examining apparatus of the type having eye fixation mark means, eye refractive power measuring means and control means for moving an image of the fixation mark depending upon the output signal from said measuring means are disclosed. Said control means comprises means for detecting the position of the fixation mark image and means for detecting the difference between the level of signal from said position detecting means and the level of output from said measuring means. When the detected difference is within a predetermined range of values, the image of fixation mark is moved by a predetermined distance.

Abstract: An eye-refractometer device has a beam splitter, a projection optical system provided in one light path of the beam splitter for projecting a light beam into the pupil of an eye to be examined and scanning the light beam, a condenser optical system provided in the other light path of the beam splitter for receiving the reflected light from the retina of the eye, the condenser optical system comprising a condenser lens, a diaphragm member and a light-receiving member, and a signal processing system for processing the signal from the light-receiving member. Light beam rotating means for rotating the light beam about the optic axis is provided between the beam splitter and the eye. The light-receiving member is fixedly disposed at a position substantially conjugate with the cornea of the eye with respect to the condenser lens and a plurality of light-receiving elements are provided on the light-receiving surface of the light-receiving member off the optic axis.

Abstract: An ophthalmological instrument capable of continuously changing the size of an observed image is disclosed. The instrument comprises an image forming optical system for forming a first observed image, a magnification changing optical system for forming a second observed image from said first image and continuously changing the size of said second image and a correction member for correcting the optical length. To continuously change the size of said second image for observation, the magnification changing optical system includes a positive lens group and a negative lens group which are movable relative to each other in the direction of the optical axis. In order to keep constant the positions of the anterior and posterior focal points of the magnification changing optical system, that is, a composite system of the two lens groups, the optical length correction member is movable in association with the movements of the positive and negative lens groups.

Abstract: A position adjusting device attached to an ophthalmologic measuring instrument to accurately position an eye to be examined with respect to the ophthalmologic measuring instrument comprises projection means for projecting a predetermined projection pattern upon the eye to be examined, an objective lens group for observing therethrough the reflected image of the projection pattern by the cornea of said eye, a field stop provided at the image forming position of the objective lens group, a light-intercepting member provided near the objective lens group and having two openings outside of the optic axis of the objective lens group, a reflecting member obliquely disposed on the optic axis of the objective lens group rearwardly of and near the light-intercepting member, a position adjusting standard chart, and a projection lens for projecting the image of the standard chart onto the position of the field stop through the reflecting member.

Abstract: An eye-refractometer device includes a light receiving member having a pair of photoelectric elements for detection of astigmatic axis and a pair of photoelectric elements for detection of diopter of an eye provided on the light receiving surface of said member off the optical axis of a condenser lens. Said pair of astigmatic axis detection photoelectric elements are positioned on a straight line normal to the scanning direction of the beam projected through said projection optical system. Said pair of diopter detection photoelectric elements are positioned on a line extending in said scanning direction. The eye-refractometer device has a highly improved accuracy of measurement of diopter.

Abstract: In a fundus observation and photographing optical system having an objective lens for forming a primary image of the fundus of an eye to be examined, an apertured mirror disposed rearwardly of the objective lens and obliquely with respect to the optic axis of the lens and having an opening on the optic axis, an illuminating optical system for supplying illuminating light to the eye via the apertured mirror and through the objective lens, and an image forming relay lens for forming a secondary image from said primary image, the objective lens has, in succession from the side of the eye, a first group comprising a biconvex lens having its more sharply convex surface facing the apertured mirror, and a second group comprising a doublet of a biconvex lens and a biconcave lens and having its concave surface facing the apertured mirror.

Abstract: A projection type lens meter comprises a projection lens system consisting of a positive lens group and a negative lens group mutually separated by a large air gap, wherein the projecting light beam having passed through said two lens groups is made to pass through said air gap between said lens groups.

Abstract: An eyeground inspecting contact lens adapted to be disposed in contact with the cornea of an eye to be inspected, in order that an illuminating light may be directed to the fundus of the eye so as effectively to illuminate the same for the observation of the eyeground, comprises a plurality of glass bodies having the incidence surface thereof inclined with respect to the optical axis. The refractive indices of the glass bodies, the inclined angle of the incidence surface with respect to the optical axis and the inclined angle of the boundary surface of each of the glass bodies with respect to the optical axis are selected such that, of the illuminating light flux, the light beam coincident with the optical axis prior to incidence on the first glass body is made parallel to but spaced from the optical axis after being passed through the glass bodies, and then impinges on the eyeground.

Abstract: A lens meter includes a target, a collimator lens system for forming an image of the target, a member having a reflecting surface facing the collimator lens system, and an indicating plate disposed at the focal point of the collimator lens system, and at a side opposite to the reflecting member relative to collimator lens system. The reflecting member is placed on the optical axis of the collimator lens system at a side opposite to the target relative to the collimator lens system. The reflecting member is movable along the optical axis and the target is placed at the focal point of the collimator lens system. The lens meter may further include a beam splitter for dividing the optical axes into two optical axes. In this case, the target is placed on one of the divided axes and the indicating member is placedon the other divided axis. Further improvement may be attained by providing in a suitable arrangement two polarizing plates and a quarter-wave plate.

Abstract: A curvature measuring optical system in an ophthalmometer comprises a first and a second lens group and rotary prisms disposed between the two lens groups. The first lens group has the focal point thereof lying at the location of the virtual image of an index projected on the cornea of an eye to be examined. The second lens group focuses on the focal plane thereof a light beam made parallel by the first lens group. The rotary prisms separate the image into two images and are rotatable in the opposite directions from each other.

Abstract: A lens meter for measuring the focal length of a sample lens with the sample lens disposed in a collimated light beam comprises a target, a first lens for forming an image of the target, light beam splitter means in the light beam on the image forming side of the first lens for splitting the light beam to form a second target image, a second lens having its focal points on the first and second target images through the light beam splitter means, target orthogonalizing means provided between the first and second lenses for making the first and second target images orthogonal to each other, a third lens for focusing the orthogonal target images collimated by the second lens, and target viewing means disposed at the focal point of the third lens.