Showing papers on "Lens (optics) published in 1980"

Gradient-index optics: a review.

Abstract: The subject of gradient-index optics dates from the 1850s. However, only in the last 10 years has it been possible to design lenses, manufacture materials, measure the properties, and fabricate finished lens elements. The current status of gradient-index optics is reviewed.

Refractive optical systems for irradiance redistribution of collimated radiation: their design and analysis.

Abstract: A set of differential equations is derived which specifies the shape of two aspherical surfaces of a lens system that will convert an incident plane wave with an arbitrary energy profile into collimated radiation with a uniform energy distribution. As an example, a lens system is designed that converts a laser beam with a Gaussian energy profile into an expanded beam with a uniform energy distribution. Off-axis rays are then traced through the lenses in order to analyze the performance of the lens system.

Brillouin scattering, density and elastic properties of the lens and cornea of the eye

Abstract: Brillouin spectra of biological systems may ultimately be related to their intrinsic molecular properties. In some instances the optical properties may be associated with the elastic ones and ultimately with the force constants of the molecules involved1,2. In the present work we have used a triple-pass Fabry–Perot interferometer to measure Brillouin light scattering spectra for refractive tissues of the eye, including cornea, capsule and lens. Combined with corresponding measurements of density, estimates of the real and imaginary parts M′ and M″ of the longitudinal bulk modulus have been made for the first time. Measurements have extended over four classes of vertebrate: Mammalia, Aves, Pisces and Amphibia; only small differences have been found between the various samples of cornea, whereas marked differences occur between the different lenses. Hence this account concentrates largely on the latter. The implications of this work lie not so much at the opthalmological level as at the macromolecular and offer, in conjunction with other scattering techniques, opportunities for probing the lens and its proteins topographically as a function of growth.

Apparatus for collecting, distributing and utilizing solar radiation

Abstract: The apparatus for collecting, distributing and utilizing solar radiation includes a solar collection panel (24) having an array of solar gathering cells (1, 37) which provide radiation to a light collecting unit (3, 4, 39). This light collecting unit (3, 4, 39) provides radiation as a single beam to a lens system (5, 7) which provides a coherent beam to a lightpipe (8). This beam is then directed to use units such as a light to electricity converter (100, 154), heat distributing elements (202, 213, 230, 244, 270) and light distributing elements (322, 336, and 348).

Applications of GRIN-rod lenses in optical fiber communication systems.

Abstract: Graded-refractive-index-rod lenses (GRIN-rod lenses) have a number of features that make them particularly suitable for use in optical devices for manipulating and processing the optical signals in fiber communication systems. Such lenses can be cemented directly to the other elements of a device, thus giving a structure that is compact, solid, stable, and rugged. They also have significantly smaller aberrations than equivalent simple homogeneous lenses, and this results in lower insertion losses. Designs for various GRIN-rod lens devices, including connectors, attenuators, directional couplers, switches, isolators and wavelength-division multiplexers are reviewed. A consistent set of loss estimates is provided for all the device designs considered.

Presbyopic contact lens

Abstract: A contact lens to correct presbyopia provides a distance correction at the center, increasing diopter adds away from the center for close and intermediate viewing and a good physical fit. The lens has a generally spherical anterior surface and a posterior surface with an annular fitting region for good physical fit and an optical region having a central portion providing a distance correction and a paracentral portion providing a gradient of diopter adds for close and intermediate viewing

Intraocular lens and manipulating tool therefor

Abstract: The invention contemplates improved techniques for making lens implants for use in ophthalmological surgery, the lens being a replacement for a cataract-clouded natural lens. The lens of the invention is particularly adapted for posterior-chamber implantation, with position stability derived from the inner wall of the natural-lens sac (from which cataracted material has been removed). A manipulative tool in combination with the lens assembly (1) provides safe stabilizing support during storage and transit prior to the surgeon's access for operative use, and (2) is configurated to facilitate operative placement of compliant retaining feet within the sac, permitting posterior-chamber positioning of the lens prior to tool removal.

Producing soft contact lenses

Abstract: A soft contact lens is provided by: pouring an excess amount of an original solution for producing a soft contact lens into a concave mold; placing a convex mold on said concave mold and overflowing the excess of said original solution to thereby uniformly fill said original solution in a space between said concave mold and said convex mold; gelling said original solution between the two molds to form therebetween a lens having a tensile strength of at least about 0.1 kgf/cm 2 ; immersing said lens and said two molds in a liquid to peel said lens from said molds; and extracting the thus-peeled lens via an extraction treatment with water. The "original solution" contains: a component A selected from the group consisting of monomers and hydrophillic polymers wherein the monomers yield hydrophillic component when polymerized; a compound B selected from the group consisting of monomers and hydrophobic polymers wherein the monomers yield hydrophobic component when polymerized; and a solvent C the weight ratio of A:B being from about 85:15 to about 55:45 and solvent C being about 5 to 95% by weight.

Application of gradient-index fiber arrays to copying machines

Abstract: A gradient-index fiber array arranged in a plurality of rows, which forms an erect image with unit magnification, is employed as a novel optical system for use in a copying machine. In this paper, the optical characteristics of the fiber array are discussed. In particular, an equation indicating the quantity of light for slit-exposure scanning is introduced. The f/No. of the N-row array is defined in a form equivalent to the f/No. of a conventional lens.

Automatic flushing system

Abstract: An automatic flushing system having an electrically-operated flush valve, a sensor for determining the presence of a person and a control circuit responsive to the sensor for initiating the operation of the flush valve. The sensor emits pulses from within a defined viewing area. A lens system is arranged to collect reflected light only from the defined viewing area. Light reflected from walls, tile or other shiny surfaces does not activate the control circuit. The sensor is mounted below and behind the flush valve actuating means so as to be partially hidden from view and thus discourage tampering with the sensor.

Apparatus for inspecting defects in a periodic pattern

Abstract: An apparatus for inspecting a defect in a periodic pattern on an object is provided with a laser device for projecting a laser beam toward the object. A mechanism further included in the defect inspecting apparatus rotates the object in a plane orthogonal to an optical path of the laser beam while moving in the same plane. A spatial band-pass filter is located at the backward focal plane of a lens for Fourier-transforming the laser beam including the information of the periodic pattern and a defect, the laser beam coming from the object. The band-pass filter has a spot-like area for blocking the zeroth order diffraction light transmitted through the periodic pattern a peripheral light blocking area for blocking the first and higher order diffracted light beams, and a ring-like light transmission area permitting the light beam component including the information of a defect to pass therethrough, the light transmission area being located between the spot-like area and the peripheral area. A photo-electric converter for picking up the light beam component including the defect information transmitted through the filter is located on an image forming plane where an image of the object is formed by a lens.

Sterile hypopyon following intraocular lens surgery.

Abstract: • Energy-dispersive x-ray analysis (EDXA) was used to study nine intraocular lenses from one manufacturer. Residual polishing compound was found on two of three dry-sterilized lenses from a "hot lot" associated with a high incidence of sterile hypopyon. Similar material was not present on normal lenses. This polishing compound was apparently fused to the lens surface, preventing its removal by ultrasonic cleaning. In addition, three wet-sterilized lenses were found to be covered with small crystals containing barium. These crystals apparently resulted from leaching of the glass storage vial by the caustic storage fluid. It is suggested that some cases of sterile hypopyon following intraocular lens surgery may be caused by residual polishing compound present on the lens surface.

Illumination optical system for an endoscope

Abstract: An illumination optical system for an endoscope in which, by arranging a cylindrical reflection member between a light guide and a lens system, a distribution curve of luminous intensity is improved with the effective utilization of illumination light and yet the formation of the image of the light guide end face on the object surface is obviated, thereby enabling attainment of a uniform illumination over the object surface.

Fiber coupling using graded-index rod lenses

Abstract: The graded-index rod lens (GRIN lens) is useful in coupling between multimode optical fibers. Applications include connectors, switches, multiplexers, and branch couplers. In these devices, one GRIN lens collimates light from an input fiber, and a second lens collects the light and focuses it on an output fiber. This paper presents analyses of power losses in these devices resulting from lateral and angular misalignments and from the spacing between the lenses. It is found that the GRIN lens coupling system is very sensitive to angular alignment but is more tolerant of lateral errors and lens spacing.

Automatic focusing camera

Abstract: PURPOSE: To accurately transmit a defocusing amount to a lens barrel device of an automatic focusing camera. CONSTITUTION: Light from a photographic lens is stored by an image sensor (I). The conversion coefficient of a central storage time t1 is received from the lens barrel device (T1), the defocusing amount is obtained based on a light quantity signal from the image sensor, and the defocusing amount is converted into a lens moving amount DP1 once by the conversion coefficient of the central storage time t1(C1). And, the conversion coefficient obtained at a time t3 just before the transmission of the defocusing amount is received from the lens barrel device (T3), the lens moving amount is corrected to a value at a time t4 just before the transmission of the defocusing amount, and then, the corrected lens moving amount DPT is converted into the defocusing amount by using the conversion coefficient obtained at the time t3 just before the transmission of the defocusing amount, and then, defocusing amount is transmitted to the lens barrel device (T4).

An easier method to obtain the sphere, cylinder, and axis from an off-axis dioptric power matrix.

Abstract: Dr. W. F. Long pointed out that calculations of decentration in spherocylindrical lenses, as well as calculations of combinations of obliquely crossed spherocylindrical lenses, are considerably simplified by the use of matrix methods. In the obliquely crossed lens problem, Long used eigenvalue techniques to obtain the sphere, cylinder, and axis of the equivalent lens. This paper presents an alternative to the eigenvalue method. This alternative method uses the invariance of the trace and determinant of the dioptric power matrix. This alternative is conceptually easier to understand than the eigenvalue method and perhaps will encourage more people to use the matrix methods.

Engraving printing cylinders

Abstract: Apparatus for engraving a rotating cylinder by means of a laser, in which the laser beam is focused onto a small area of the cylinder surface by a lens, including means for defining a path for the flow of compressed air across the path of the laser beam, and a suction device communicating with the region between the lens and the cylinder for extracting air from this region, the flow of air serving to remove debris from the area being engraved and to prevent it from reaching the lens.

Progressively varying focal power opthalmic lens

Abstract: A progressively variable focal power ophthalmic lens. The lens has a unique geometry which allows the correction of distortion of horizontal and vertical lines to be retained below detectable levels in the temporal peripheral zone of the lens after the lens is rotated to accommodate the left or right eye. In addition, the geometry further allows the minimization of the astigmatic aberration in the area of the peripheral zone adjacent to the distance portion and the elimination of the astigmatic aberration in the lower part of the temporal peripheral zone.

Synthetic formation of defect-free images - by superimposed blurring images of defect on reconstituted multiple perspective images

Abstract: A method and arrangement for tomographic synthetic image formation involve passing light through the object (6) from several positions to form perspective images (11) on a recording medium (10). The images are smapled by placing a lens at the source positions so as to superimpose them on a light sensitive layer, thus recording the visual image. The arrangement is designed to produce a natural locking image without defects. The perspective image is partially overlayed by a blurred image derived from the perspective image and of an intensity corresp. to that of the defect present in the image. The blurred image may be conducted by superimposing several visual images lying in front of and/or behind the layer image. This may involve moving the recording medium, lens and/or light sensitive film along the optical system axis.

Process and device for laser-beam melting and flame cutting

Abstract: In a laser beam cutting device the focussing of the laser beam (1) and the adjustment of the focal spot (4) in respect of its vertical position is made swing free, and is achieved without subsequent correction of the workpiece coordinates, with the focussing lens (2) guided strictly parallel and coaxial with the optical axis. By active cooling of the surface of the workpiece in the immediate area of the focal spot (4), the critical heating-up zone is reduced and the accuracy and surface finish of the cut edge is improved.

Coupler comprising a light source and lens

Abstract: For many optical communications systems, a semiconductor laser must be situated at an exact position and at an exact distance from a first optical element (for example a lens) of the optical system coupled to the laser. This is achieved according to the invention by arranging the laser in a bushing-shaped cover on which a flange is formed. A holder with a lens is secured on this flange by way of a plastic metal solder layer. The lens can be placed at the correct position and at the correct distance from the laser by sliding and by pressing on the holder. The solder layer is then plastically deformed while the space in which the laser is accommodated remains hermetically sealed.

Device for focus and alignment control in optical recording and/or playback apparatus

Abstract: A device for controlling focus and alignment of a light beam, e.g. in apparatus for optical recording and playback with high density data storage media such as optical discs, includes a plurality of independently addressable piezoelectric bender elements which control the position of lens means of such apparatus. The bender elements can be selectively addressed with electric fields to effect focus and/or tracking alignment adjustments of the active light beam.

Lighting systems for surgical operations

Abstract: This invention relates to lighting systems for use during surgical operations or examinations. The device comprises a bundle of optical fibres having an intake area into which the light from an ellipsoidal mirror having a lamp therein can be beamed. A concave lens area located in an area facing away from the optical fibre bundle is co-axially situated forwardly adjacent the light intake area of the fibre bundle. The concave area may be formed by grinding out portion of a transparent plate and the light from the mirror may be concentrated by an aspheric lens between the mirror lamp and the lens area.

Clinical method for measurement of light backscattering from the in vivo human lens.

Abstract: A simple clinical method for measurement of light backscatter from defined regions of the lens in vivo is described. Light scattering was quantitated in 168 lenses of 85 "normal" subjects spanning 8 decades of life. The results indicate that light scatter from the anterior capsule does not change with age. The light scatter from the anterior cortex is quite significant even in young lenses and gradually increases with age. The backscatter in the nuclear region is minimal in young eyes, increasing gradually up to the age of 40, after which it exhibits a sharp increase.

Optical reproducing head

Abstract: An optical reproducing head for reproducing an information signal recorded on an optical record medium includes a semiconductor laser for generating a laser beam, a first off-axis hologram lens irradiated with the laser beam from the semiconductor laser to produce a beam of parallel rays of light that has an optical axis which is off-set with respect to the optical axis of the laser beam, a second off-axis hologram lens irradiated with the beam of parallel rays of light from the first off-axis hologram lens to generate a focused beam which has an optical axis which is off-set with respect to the optical axis of the beam of parallel rays of light and has an optical axis perpendicular to the optical record medium, and a photo-detector detecting the intensity of a non-diffracted wave beam from the first off-axis hologram lens means, the non-diffracted wave beam being at least part of the focused beam which has been reflected from the optical record medium and has been diffracted by the second off-axis hologram lens. The output of the photodetector is used to produce a focus error signal and a tracking error signal for controlling the focus servo and tracking servo operations.

Two-dimensional scanning device having compensation for scanned image strain

Abstract: A two-dimensional scanning device provided with a first deflector for deflecting a collimated beam, a second deflector for deflecting the incident beam in a direction orthogonal to the deflection direction of the first deflector, a scanning lens disposed between the first deflector and the second deflector, a scanning surface for imaging the scanning beam from said scanning lens through the second deflector, and a device for moving the scanning lens in the direction of its optic axis in synchronism with the rotation of the second deflector to thereby obtain a strain-free two dimensional scanning figure on the scanning surface

Gradient-Index Optics: A Review

Abstract: The subject of gradient-index optics dates from the 1850s. However, only in the last 10 years has it been possible to design lenses, manufacture materials, measure the properties, and fabricate lens elements. The current status of gradient-index optics is reviewed.