Abstract: An eye examining apparatus is disclosed which is capable of the accurate detection of any abnormality in the optical system of a patient's eye which might exist at any position of the eye, and also which is capable of providing easy measurement of the degree of refraction of the patient's eye. The apparatus comprises a target projecting system for projecting onto a retina a target image to be measured; focalizing means for detecting the focus of the target to be measured and for focalizing it on the retina; and an optical transfer function measuring system for detecting the contrast of the target image to be measured, which is focalized on the retina, and thereby measuring the optical transfer function of the patient's eye.The apparatus may further comprise means for comparing the measured optical transfer function with that of a normal eye, and the target projecting system may include a means for rotating the target image to be measured around an optical axis.

Abstract: An automatic marking device for a lensmeter comprising: a lens support member; a lens holder having a lens holding member cooperative with the lens supporting member for clamping therebetween the lens movably in a plane substantially perpendicular to a measuring optical axis of the lensmeter; a marking device having a marking unit movably mounted on the lens holder and having at least one marking stylus. The marking unit is carried for rotation about an axis which is parallel to the measuring optical axis. Two hands having inner surfaces are provided and adapted for contacting adjacent edges of the lens such as to clamp the lens therebetween. A hand moving device is provided for moving the hands in the plane in accordance with the result of measurement of the refraction characteristics of the lens.

Abstract: An eye fundus camera having an automated focus control system which includes a mark projecting system for projecting a focus detecting mark to the retina of a patient's eye to produce a mark image and a photoelectric system for detecting the mark image to judge the focus condition. The photoelectric system produces electric signals which are compared with a threshold level signal to produce mark image signals. In order to ensure an accuracy of detection of the mark image, the threshold level can be changed when it is judged as inappropriate.

Abstract: A non-contact type tonometer for measuring intraocular pressure of a human eye. The tonometer includes a fluid ejection nozzle to eject a fluid toward a cornea of an eye to be tested and an alignment control apparatus. The alignment control apparatus comprises a pair of alignment control systems disposed in a manner as to intersect the respective optical axes at one point on the central axis of the fluid ejection nozzle and to be symmetrical about the central axis. The alignment optical systems each include an index projection optical system for projecting an index spot light toward the cornea and an index detection system for forming a virtual image of the index spot light produced by means of corneal specular reflection from the eye on an observation system as an index image through a part of an index projection optical system of the other alignment optical system.

Abstract: An inclination measuring apparatus having a prism and a container having a liquid sealed therein for providing a liquid surface perpendicular to the direction of gravity. A member constructed from thermal conductive material is position under the liquid surface to maintain the liquid surface level in the presence of ambient temperature changes.

Abstract: A fail-safe laser apparatus includes a laser beam radiation source for emitting a laser beam along an optical axis, a main shutter for intercepting or attenuating the laser beam incident thereon in its closed position, and a safety shutter for completely intercepting the laser beam incident thereon in its closed position. The main shutter is moved to its open position in coagulating the diseased part. A first sensor produces a first signal indicative of the intensity of the laser beam emitted along the optical axis between the radiation source and the main shutter. A second sensor produces a second signal indicative of the intensity of the laser beam emitted along the optical axis between the main shutter and the safety shutter. A detection circuit is responsive to the first and second signals for actuating a safety shutter control means to move the safety shutter to its open position in accordance with the first and second signals.

Abstract: An illumination system is provided for a single objective lens-type binocular microscope. The arrangement features a slot cut in a single objective lens. A prism is inserted into this slot. An illuminating light flux is conducted to the prism at an axis different from the axis of observation through the objective lens. The prism conducts this light to the axis of observation so as to illuminate the area to be observed. Thus, the angle between the illuminating light flux and observing light flux can be made extremely small permitting the deep illumination of the area to be observed.

Abstract: A binocular microscope arrangement that can be used for both straight line and angular viewing. The microscope arrangement includes three main units: an objective lens unit, a deflection prism unit, and an ocular tube unit. Mounting Structures are provided at the light-outgoing side of the objective lens unit at boxer sides of the deflection unit and at the light-incoming side of the ocular tube unit can be directly coupled to the objective lens unit, or the deflecting prism unit can be interposed between the ocular lens unit and the objective lens unit.

Abstract: Method for determining a refractive index of an object in which the object is illuminated with a slit pattern of illumination light to form an optical section of the section of the object and the optical section is observed in two directions to determine apparent thickness of the optical section in these directions. Operations are carried out to obtain the refractive index of the object from the apparent thickness of the optical section.

Abstract: A level detector comprising a container holding two fluids. Four capacitors are formed between four electrodes disposed on one side of the container cooperating with an opposing common electrode. Two of the capacitors have a capacitance value influenced by the position of one of the fluids in the container (related to container tilt) but in inverse relationships. A third capacitor is influenced by the dielectric value of the two fluids but in a manner independent of the tilt angle of the container. The fourth capacitor has a capacitance value influenced only by the dielectric constant of one of the two fluids. Based on the four capacitance values, circuitry is provided for generating a signal relating to the angle of the container.

Abstract: An operation microscope system comprising an operation microscope including an observation optical system adapted for observing a portion of a patient wherein an operation is to be made. A mark device is provided on one of the microscope and the patient's portion and a mark position detector is provided on the other.A control circuit is provided and has a memory for memorizing an initial position signal as produced by the detector when an initial focus condition or a visual field is established between the patient's portion and the microscope and an out-of-focus condition or a change in the visual field is detected by a relative displacement between the patient's portion and the microscope based on the initial position signal and an actual position signal as produced by the detector to produce a correcting signal to thereby restore the initial focus condition or the initial visual field.

Abstract: An electronic flash including a discharge flash tube controlled by a first switch and a commutation capacitor for controlling the first switch. There is provided a second switch for governing the operation of the commutation switch. A charging circuit is provided for charging the commutation capacitor and includes a resistor connecting the commutation capacitor with an electric power source. The resistor has a resistance value which is small enough to allow a current not smaller than a current at which the second switch is turned off.

Abstract: An encoder including a code carrying medium movable with respect to a photoelectrical sensor in one direction, the code carrying medium having a first track formed with a plurality of first blocks arranged along the aforementioned direction of movement of the code carrying medium, each of the first blocks carrying address information of the particular block recorded in a direction crossing the direction of movement of the code carrying medium, and a second track parallel with the first track and formed with a plurality of second blocks arranged along the direction of movement, each of the second blocks carrying reference position information representing a reference position of the particular one of the second blocks and a plurality of coded bar patterns arranged with a first predetermined pitch in series along the direction of movement of the code carrying medium.

Abstract: An apparatus for measuring the optical characteristics of an optical system includes a light source, collimator means for collimating a beam of light from the light source, a mask means, a means for holding the optical system to be tested between the collimator means and the mask means, a detector, a calculator, and first beam splitting means. The mask means includes at least one mask provided in each optical path following the first beamsplitter means, each having a linear band group consisting of at least two parallel linear bands, with each mask disposed to provide a different orientation for the linear bands.

Abstract: A stereo-microscope is disclosed. It comprises a common objective lens system, a first and second imaging lens systems having optical paths parallel to that of the objective lens system producing intermediate images of an object, a first and second optical path deflecting devices arranged behind the respective imaging lens systems for deflecting the respective ejection bundle of rays outwardly relative to the optical path of the objective lens system, and a first and second ocular systems arranged behind the respective optical path deflecting devices for observing the respective intermediate images. It is characterized in that a stereo angle .omega. which is to be decided depending on the base length between the first and second imaging lens systems and an observation angle .theta. which is defined between the observation optical paths of the first and second ocular systems are arranged to be equal. Another stereo-microscope is also disclosed.

Abstract: A specular microscope in which the image of a slit aperture of an illumination optical system is formed at an endothelial cell layer of an eye to be examined and including a light intercepting plate having a main aperture and additional apertures adjacent said main aperture so that an image of the endothelial cell layer is formed at said main aperture and a reflection light reflected by a corneal surface of the eye is transmitted through said additional apertures of said light intercepting plate.

Abstract: An eye refractometer comprising a measuring target projection optical system for projecting a measuring target image to the eye fundus of a patient's eye by means of a pair of beams of light from a measuring target; a rotating device for rotating the pair of beams of light around the optical axis; a measuring target image-forming optical system for forming a target image of the beams of light projected through the measuring target image projected to the eye fundus; a detection device for two-dimensionally detecting the position of the target image formed by the image-forming optical system on a plane perpendicular to the optical axis; and an operating circuit for obtaining a refractive power of the eye along a radial line passing through the centers of the pair of beams of light by means of the signal from the detection device.

Abstract: An improved telescope is disclosed in which an adjusting member for adjusting the reticule can be fitted on an optical axis thereof. The improved telescope has a reticule disposed at an ocular side in a lens-barrel and including a cross line for collimation; a reticule holding member including a front surface parallel to the reticule surface and a rear surface having at its periphery an inclined portion inclining with respect to the cross line surface and disposed within the lens-barrel for holding the reticule; a reticule holding member fitting portion disposed within the lens-barrel and receiving the reticule holding member by abutting against its front surface of the reticule holding member; and an adjusting member abutted against the inclined portion of the rear surface of the reticule holding member from the ocular side toward the optical axis direction to move the reticule holding member in order to adjust the cross line to the optical axis.

Abstract: A curvature measuring apparatus is provided for measuring the radii of curvature of a curved surface, particularly a human cornea or a contact lens. The apparatus comprises an illuminating optical system which illuminates the surface to be measured. The optical system includes a light source for forming a pattern of radiating beams of at least two groups, with each group being comprised of at least two parallel straight lines in a virtual plane. The straight lines in one group are different in directions of arrangement from the straight lines in the other group, and each group includes at least one line whose characteristics are substantially different from the other lines in the group to serve as a reference line. A collimator lens orients principal rays of illuminating beams of light emitted from the light source through a pin hole arranged on an optical axis, to be parallel to the optical axis so as to illuminate the surface to be measured by the illuminating beams of light.

Abstract: An ophthalmic photographing apparatus for determining the exposure condition of ophthalmic photographs, includes an illuminating optical system for illuminating a subject to be photographed, a photographing optical system for photographing the subject, an exposure control system comprising light detecting means for detecting intensities of light reflected at a plurality of zones of the subject, boundary level setting means for dividing a region between the highest and lowest values of the light intensities detected by the detecting means into a plurality of sub-regions and determining a boundary value between each two adjacent sub-regions, exposure condition setting means for setting a selected one of the sub-regions, comparator means for comparing output of the detecting means with the boundary value related to the selected sub-region to thereby select the outputs included in the selected sub-region, and exposure control means for controlling exposure in accordance with the selected outputs of the detecting