Abstract: A catadioptric optical imaging system comprises a dioptric assembly (20) and a catoptric assembly (21), which are positioned with respect to each other to form an imaging system of long focal length. The dioptric assembly (20) comprises two confocal paraboloidal mirrors (22, 23) arranged to form a telescope of the Mersenne type. The catoptric assembly (21) comprises lens elements arranged in two groups, viz., a field group (25) and a relay group (26), which are coaxially disposed with respect to the dioptric assembly (20). Only two different optical materials, viz., calcium fluoride crystal and Hoya LAC7 glass, are used in making the lens elements of the dioptric assembly (20). The dioptric assembly (20) is color-corrected at five wavelengths and has only negligible secondary and higher-order spectra in a wavelength band extending from the ultraviolet region to the near infrared region of the optical spectrum.

Abstract: An ophthalmological diagnosis method and an apparatus for carrying out the method are disclosed. According to the method a region of the eye, e.g. the fundus, is illuminated with a laser beam of prescribed diameter to produce a laser speckle pattern formed by light scattered by blood cells within the tissue of the eye, movement of the laser speckle pattern is detected as fluctuation in the light intensity of the speckles at an observation point and a speckle signal corresponding to the detected movement is produced, the power spectrum distribution of the speckle signal is obtained, the power spectrum distribution configuration is evaluated from the results of a calculation of the mean frequency thereof and the blood flow state in the tissue is determined from the results of the evaluation.

Abstract: The device comprises a sleeve element locatable on a portion of each eyeglasses leg coaxially therewith, and a half-tubular element provided with a plate-like end for connection to the end of the strap, said half-tubular element having an inside profile that conforms with the outside profile of said sleeve whereover it is engageable by snap action.

Abstract: A control system for use with a conventional photocoagulation device for controlling the exposure parameters of irradiation of biological tissue, such as the fundus of an eye. The photocoagulation device includes a source of radiation, a means for initiating and terminating the source of radiation, and sensing means for measuring the extent of coagulation of the biological tissue. Exposure parameters of the device include exposure time and the wavelength spot size and power of the irradiating beam. The control system cooperates with the device for determining and regulating the exposure parameters in accordance with the unique mathematical relationship between the extent and progression of coagulation during a photocoagulation operation, thereby to terminate the photocoagulation operation should unsatisfactory results be anticipated.

Abstract: Eyeglasses for intermittent use which can be flat folded and flipped up when not in use, include a cross-bar which extends the width of the eyeglasses. A lens plate is rotatably mounted to the cross bar. Right and left temples extend substantially perpendicularly from opposite ends of the cross bar and are rotatable relative to the lens plate. The temples are composed of a lower temple piece and a temple piece extension. The lower temple pieces extend substantially perpendicularly from opposite ends of the cross-bar. The temple piece extension is rotatably connected to the lower temple piece by for example, a pivot. A nose bridge is located in the middle of the cross bar and is rotatably mounted to the cross bar independent of the rotation lens plate.

Abstract: Device for measuring eye movements. At least two radiation sources are located in front of the eyes and at least two radiation detectors are adapted to detect the radiation reflected from the eye, whereby the detectors are located in connection with the radiation sources. In accordance with the invention the radiation sources (3,4) and the detectors (5,6) are disposed in pairs so that one pair is arranged on each side of at least one symmetry plane through the centered eye. The at least two pairs are disposed on a diaphragm (1) which is located at a certain distance from the eye (8) and which is provided with an aperture (2) straight opposite to the eye having a certain form and size thereby to permit the eye to look through the aperture within a certain space angle. A shielding member (7) is disposed aroused the diaphragm and the eye in order to prevent disturbing light from impinging into the eye beyond the light falling through the aperture.

Abstract: A fast telephoto lens has a longer focal length of 300 to 400 mm, and an F-number of about 2.0 to 2.8, which does not utilize a floating mechanism, has a small deviation in aberration when the lens is focused on an object, and has a simple construction for shifting only one lens group. The fast telephoto lens is of internal focusing type and comprises positive, negative and positive lens groups from the object side, and only the negative (second) lens group is shifted to obtain an in-focus state.

Abstract: A zoom lens comprises, in succession from the object side to the image side, a positive first lens group movable for focusing, a negative second lens group movable for zooming, a positive third lens group movable for zooming, a negative fourth lens group movable for zooming and moved with the second lens group, and a stationary fifth lens group. When .beta..sub.i is the lateral magnification of the ith lens group as counted from the object side, the lateral magnification of each of the lens groups satisfies at a point in zooming.beta..sub.2 <0, .beta..sub.4 <0, .beta..sub.2 .beta..sub.4 =1, .beta..sub.3 =-1and satisfies at the point-1.3<.beta..sub.2 <-1.025.

Abstract: Sunglasses have a unitary transparent pane extending in a curved plane and over the wearer's nose bridge. The sunglasses frame and nose-piece construction permits their ease of removal and replacement, as well as pane replacement; and provision is made for stem pull-away; frame padding; and elastomeric pads to engage the sides of the wearer's nose.

Abstract: The invention relates to a method for determining the refraction of the human eye. The retinal image of an object is imaged via a lens system into an object space and into an image plane which is conjugated with respect to the retina. The spacing of the conjugated plane is analyzed to determine the refraction of the human eye. This analysis is carried out by means of a measuring object which is moved along a plane which is defined by rays of the beam of rays which pass through image points of the retinal image of a target object, such that the beam of rays is divided into two complementing partial beams containing an unevenly divided amount of light energy. The unevenly divided light energy is used to determine the distance of said conjugated plane.

Abstract: An apparatus for performing measurements on the eye of a subject includes a headrest for supporting the head of the subject in a fixed position, and a frame holding a light source directing illumination at the eye. The frame is adapted for pivotal motion about a central axis of the eye. Imaging means provides an image of the first and fourth Purkinje images of the light, and means are provided for measuring the amount of rotation of the frame. The frame may be initially aligned so that a fixation target lies in the plane defined by the central axis and the light source, and then rotated until the first and fourth Purkinje images determine a straight line parallel to the central axis, whereby the plane is aligned with the optical axis of the eye. The net rotation of the frame then gives a direct reading of the angular difference between the line to the target and the optical axis of the eye. Preferably the apparatus includes an infrared light source.

Abstract: A rear conversion lens system to be used for varying the focal length being inserted to the space between an objective for a single-lens reflex camera and film surface, the rear conversion lens system comprising a first lens component arranged as a positive lens, a second lens component arranged as a negative lens, a third lens component arranged as a positive meniscus lens, a fourth lens component arranged as a biconcave lens, and a fifth lens component arranged as a positive cemented doublet, the rear conversion lens system being arranged that the magnification is higher than 1.6 and aberrations are corrected favorably.

Abstract: In the disclosed zoom lens, a positive front lens unit and a negative rear lens unit are moved forwardly axially in differential relation to vary the overall focal length from a minimum to a maximum value, while a positive middle lens unit is kept stationary during the variation of the focal length. A diaphragm determining the F-number is positioned at a fixed point between the front and rear lens units.

Abstract: An exercise device for improving poor visual acuity is disclosed in which a subject must identify randomly chosen figures of minimal visual stimulus projected in a darkened chamber. Earphones are provided to aid in the isolation of the subject and provide audio feedback. The device provides effective treatment for certain eye conditions involving poor acuity and is particularly effective in treating the eye condition known as amblyopia.

Abstract: The eyeglasses include a first and second transparent member affixed to an intermediate nose portion wherein the desired plane of the transparent member-nose portion combination can be readily altered by moving the transparent members. First and second suspension lines are affixed to the first and second transparent members and threadedly engage first and second earpieces.

Abstract: The invention contemplates instrumentation to aid in performing refraction-corrective surgery on the cornea, (1) by determining the topography of the anterior surface of the cornea, the determination being in the form of digitized data entered into computer storage, (2) by determining the local thickness of the cornea along multiple axes, the determination being also in the form of digitized data entered into computer storage, and (3) by providing a CAD/CAM display of both categories of data, correlated as appropriate for the surgeon's selective display of a corneal region, aspect or section, as the surgeon may deem pertinent to a prospective operation.

Abstract: An improved structure for providing a decorative pattern over the surface of sunglasses, the structure combining a positive decorative pattern on a first layer, a reflective layer, and a third layer incorporating a negative decorative pattern. The decorative pattern is readily apparent to an observer, but the negative pattern cancels the image for the wearer who then sees only a uniform color or hue that does not interfere with his vision or cause an unpleasant distraction.

Abstract: Visual aid especially for weak-sighted persons and comprising a sleeve into which at least one lens is fittable having the desired optical properties. The sleeve is intended to be fitted into an opening in a spectacle glass and be fixed in an optional position for individual adjustment of the distance between the person's cornea and the lens surface.

Abstract: Ophthalmoscopic instrument having working position detector. An object lens has an optical axis and is adapted to be positioned to confront a patient's eye at a working distance. The patient's cornea has a center of curvature. An observing optical system focuses a light beam reflected from the eye and passing through an objective lens on an image plane. A detecting system detects that the eye is properly positioned with respect to the objective lens. The detecting system includes at least two apertures allowing light beams from a single target mark to pass therethrough. A target mark projection system projects the beams passed through the respective apertures in directions crossing each other on the optical axis of the objective lens so that a target mark image is formed at the center of curvature of the cornea when the eye is properly positioned with respect to the objective lens.

Abstract: A slit lamp comprising a slit light projection optical system having a slit aperture for projecting a slit pattern light along a slit plane to a crystalline lens of a patient's eye and a microscope for observing a section of the crystalline lens which is illuminated by the slit pattern light. The microscope comprises an crystalline lens section recording optical system including a recording device having an image plane for recording the section of the crystalline lens of the patient's eye illuminated by the slit pattern light, and a retroillumination image recording optical system for guiding a retroillumination image of the crystalline lens to the recording device of the crystalline lens section recording optical system for recording the section of the crystalline lens.