Abstract: A field test apparatus and method is disclosed in which gradual movement of the head supporting chin cup is used to maintain a centered relation between the eye being tested and the trial lens frame holding the required prescription for optimum vision of the patient. During the test, alternating illumination is provided in the infrared between a central corneal reflection and an iris illuminating source which imparts a high contrast bright circular iris image surrounding a central dark pupil. Content addressable memories are used to delineate areas of contrast change for rapid and abbreviated microprocessor analysis of conventional RAM images. Both the corneal reflection image--which is a brightly illuminated spot on an otherwise dark background--and the pupillary image--which is a dark pupil surrounded by a brightly illuminated high contrast image of the iris are approximately located at their boundaries using content addressable memory.

Abstract: In a color field test where the field background is of a first color--preferably yellow--and the illuminating spot is of a second and different color--preferably blue, a translucent occluder is utilized for the eye. The translucent occluder is chosen to permit entry of light having the color of the background--here yellow--while filtering out substantially all light of the spot color--here blue. There results the ability to conduct a field test in color where retinal rivalry interference with the test is held to a minimum.

Abstract: A high frequency focused transducer may be formed by fabricating a piezoelectric or ferroelectric wafer of a thickness less than about 100 microns and bonding a malleable sheet to the wafer with a thin layer of adhesive. Thereafter, the composite may be pressed into a spherical mold to form a curved transducer without fracturing the wafer. In another embodiment, a conductive adhesive layer may be applied to the wafer to a thickness sufficient to hold the wafer in a curved state, when set. After the adhesive is set, the composite may be pressed into the mold while the adhesive is held at an elevated temperature whereat it is elastic. Thereafter the composite is cooled so that the adhesive layer is stabilized and the curved transducer is removed from the well.

Abstract: A computer indicated lens movement direction protocol is utilized in combination with a lensmeter to designate required movement of lenses with respect to a lensmeter to insure sequential measurement of progressive addition lenses. Lens measurement occurs at four sample points closely spaced on the lens surface. The system uses power variations (PV.sub.1 and PV.sub.2) at each of the spaced apart lens sampling points to indicate when sampling of the lens occurs in a region of constant spherical power, when sampling of the lens occurs in a region of changing spherical power, and finally when sampling again occurs in a region of constant and increased spherical power. When sampling of the lens occurs in a region of changing power, lens movement is guided along a path of constantly changing sphere utilizing changes in astigmatism measured in the 45.degree.-135.degree. directions (C.sub.X).

Abstract: In an eye field tester, a vidicon camera observes the eye being tested and relays the resultant low light level image to the periphery of a digital display. The digital display contains both an image of the eye on the periphery and the plot of the visual field of the eye under test in the center. The vidicon observing the position of the eye has its horizontal and vertical sync pulses software generated to presettable counters. These counters generate corresponding delayed horizontal sync and vertical sync pulses for the vidicon. As a result of the delayed sync pulses, the central eye image of the vidicon is offset to the periphery of the digital screen (typically to the upper left-hand portion thereof). The offset image is gated into character spaces on the digital screen utilizing software generated character attribute.

Abstract: An optical system for forming an image of the retina of the human eye. The system includes a rotating drum having transmission/receiving slit pairs formed thereon. The rotation of the drum scans an illumination region and viewing beam across the retina. Embodiments for forming stereo images, for synchronizing the formation of the image of the retina with the sweep of a vidicon tube, for automatically focusing the system, for providing flare control, for providing displaced slit functions, and for providing multiple functions are included.

Abstract: A wide angle lens system of at least two, and preferably four, similar powered symmetrical component lenses is disclosed; these lenses are from object to image, at least two paired concavo-convex lenses, and preferably two lenses of a concavo-convex or convexo-convex type. The first and last lenses are displaced and rotated usually by rotation about the object (taken as a defining aperture of the optical system, such as a portion of the cornea) or its conjugate, in a first direction to use lens portions between the lens center and one edge; the intermediate lens (preferably the second and third lenses) are displaced and rotated (again usually by rotation about the image conjugate formed by the first lens) in an opposite direction to use the lens portions between the other lens edge and center.

Abstract: An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface.

Abstract: A light pen of the type having a photoreceptor for sensing the signal from a CRT computer display and outputting to computer logic the location of the photosensing light pen is disclosed. The improvement herein is the incorporation of an accelerometer on the light pen actuated by tapping the pen gently on the screen. The accelerometer has the preferred form of a microphone acoustically deadened as by the placement of silicone rubber over the acoustical channel. The rubber acts as an accelerometer mass outputting a high frequency signal upon tapping of the light pen on the glass covering a CRT screen. A monostable amplifier opens a signal gate to conventional computer measuring logic for that duration necessary to assure one complete raster sweep of the screen. A light receptor at the screen end of the light pen outputs through a video amplifier and fast comparator to measure the precise moment of video raster passage.

Abstract: In an eye field tester, a vidicon camera observes the eye being tested and relays the resultant low light level image to the periphery of a digital display. The digital display contains both an image of the eye on the periphery and the plot of the visual field of the eye under test in the center. The vidicon observing the position of the eye has its horizontal and vertical sync pulses software generated to presettable counters. These counters generate corresponding delayed horizontal sync and vertical sync pulses for the vidicon. As a result of the delayed sync pulses, the central eye image of the vidicon is offset to the periphery of the digital screen (typically to the upper left-hand portion thereof). The offset image is gated into character spaces on the digital screen utilizing software generated character attribute.

Abstract: An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface.

Abstract: An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface.

Abstract: An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface.

Abstract: A field tester wherein a patient's tested eye is located at the center of an interior hemisphere defining a projection surface and wherein a light spot is projected onto said surface from an eccentric location is disclosed. Optics in common with the projector assure that the off-center projected light is of constant intensity and diameter as selected for each test sequence according to test criteria. Specifically, a filament light source is projected to a collimating lens. The light source is re-imaged to a system lens stop. There is a movable aperture between the collimating lens and the first lens of telescopic optics for projecting the image of the aperture onto the projection surface of the sphere. By using a coordinate transform to predict the distance from the point of light source projection to the projection surface of the sphere, the movable aperture is registered to a conjugate distance with respect to the telescope optics.

Abstract: An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface.

Abstract: A keratometer is disclosed in which at least some of the light entrance and exit paths have both peripheral entrance and exit paths. Eye positional information and sphere, cylinder and axis information for each sampled area (preferably in the order of 3) are obtained by analysis of the reflected and returned light. Sample of a multiplicity of areas on the eye occurs simultaneously without eye panning and generates a topographical measurement of the eye useful for contact lens fitting eliminating most of the incidence of refit on patients in placement of prescribed contact lenses. In one embodiment, a moving boundary locus sweeps an area of light emission from a plurality of coded, spaced apart point light sources. The area of light swept is imaged from the source to the cornea.

Abstract: An analysis of the corneal shape through the combination of several keratometer measurements is disclosed. The eye is preferably scanned to a nasal angular position, a central angular position and a temporal angular position. The central position is straight ahead along the patient's line of sight. The temporal and nasal positions are in the broad range of up to 5.degree. to 22.degree.; the intermediate range of 10 to 15.degree.; and the narrow range of 12.degree. to 14.degree. on either side. Measurements in sphere, cylinder and axes are taken. Astigmatism is in the more preferable format of 0.degree.-90.degree. astigmatism and 45.degree.-135.degree. astigmatism. When each individual point is measured with its respective estimate for sphere and cylinder components, these measurements are fitted to an idealized parameter. Then the three sets of curvature measurements taken at the specified locations are reduced to a set of adjusted, idealized curvatures all fitted to an elliptical model.

Abstract: A reflection rejecting spherical optical train is disclosed. At least two optical elements each having cylindrical components are disposed along an optical axis. The elements are each crossed one with respect to another so that the total and combined optical output comprises an overall spherical lens. Each of the lens elements having a cylindrical component is tilted with respect to planes normal to the optic axis. Light passing along the optical axis which is reflected at the defined optical interfaces is rejected by the reflection at angles which do not include a return along the optic axis; reflection rejection occurs. Preference is given to a lens train of three or more lens elements having cylindrical components, with the near point of each tilted lens element being located at equal angular intervals about the optic axis.

Abstract: A keratometer is disclosed for remotely measuring corneal curvature in at least sphere, cylinder, and axis. Assuming the eye is precisely positioned from measurement, light sources are overlapped and imaged to a virtual image position behind the human cornea. The sources of light - preferably three in number (although more than three can be used) - each have their own discrete paths from the source to the eye and then to their own discrete detector. Between the light source and the eye, each light path is interrupted by a moving boundary locus having a transparent portion, an opaque portion, and a boundary therebetween. The moving boundary locus is in turn imaged by reflection from the cornea being measured to a real image position superimposed to and upon a light detector. The detector for each eye path is aligned to and toward the virtual image produced by the light source in the precisely positioned eye.

Abstract: A process and apparatus for the calibration of an optical instrument. An optical instrument--such as a lens meter or ophthalmometer--is provided with a light source, a light detector, and an optical train of assembled optical elements therebetween. A suspect optical element to be measured is placed within the optical train at a measuring interval to deflect light passing along the optical train. An occulting moving boundary locus having at least two boundaries of differing shape, and a dedicated computer may be used to measure beam deflection. The dedicated computer also makes use of stored computer constants to transform raw measurements into the desired optical properties of the suspect optical element. The optical train of the instrument has its assembled optical elements randomly placed to production tolerances; precision registration of the optical elements to traditional close optical tolerances is omitted.