Showing papers on "Lens (optics) published in 1987"

Intelligent information-sharing systems

Abstract: The Information Lens system is a prototype intelligent information-sharing system that is designed to include not only good user interfaces for supporting the problem-solving activity of individuals, but also good organizational interfaces for supporting the problem-solving activities of groups.

Aging of the human lens

Abstract: The optical density of the human lens changes during life. Literature concerning both the spectral density function and the rate of such changes is reviewed. Analysis indicates that two components govern the spectral lens density function, with one increasing gradually during life. The average lens density increases linearly at 400 nm by 0.12 density unit per decade between the ages of 20 and 60 and by 0.40 density unit per decade above age 60. A tabulation of the two components of the average 32-yr old lens is given, as are equations to derive the average spectral lens density functions for observers aged 20–80.

An investigation of student understanding of the real image formed by a converging lens or concave mirror

Abstract: Student understanding of the real images produced by converging lenses and concave mirrors was investigated both before and after instruction in geometrical optics. The primary data were gathered through interviews in which undergraduates taking introductory physics were asked to perform a set of prescribed tasks based on a simple demonstration. The criterion used to assess understanding was the ability to apply appropriate concepts and principles, including ray diagrams, to predict and explain image formation by an actual lens or mirror. Performance on the tasks, especially by students who had not had college instruction in geometrical optics, suggested the presence of certain naive conceptions. Students who had just completed the study of geometrical optics in their physics courses were frequently unable to relate the concepts, principles, and ray‐tracing techniques that had been taught in class to an actual physical system consisting of an object, a lens or a mirror, and a screen. Many students did not seem to understand the function of the lens, mirror, or screen, nor the uniqueness of the relationship among the components of the optical system. Difficulties in drawing and interpreting ray diagrams indicated inadequate understanding of the concept of a light ray and its graphical representation.

Anterior chamber lenses. Part I: Complications and pathology and a review of designs.

Abstract: Clinicopathologic data to assist ophthalmologists in choosing a safe and efficacious anterior chamber intraocular lens (IOL) are rapidly becoming available. Two important factors that have led to an increased success rate with some anterior chamber IOL styles are (1) attention to lens design and (2) attention to modern manufacturing and lens finishing techniques. We now know much more about how to achieve appropriate lens flexibility, which decreases the need for perfect sizing. Increased attention has been given to the anterior-posterior vaulting characteristics of IOLs. This has reduced the incidence of various complications such as the intermittent touch syndrome and the uveal chafing syndrome. We recognize several design flaws in some lens styles. For example, there is now a considerable decrease in the number of small-diameter, round-looped anterior chamber IOLs being implanted, particularly those with a closed-loop configuration. Several problems have been and continue to be caused by some poorly manufactured anterior chamber lenses with sharp optic and haptic edges. Technology to assure smooth lens finishing and polishing is available and readily accessible to all manufacturers. Defective lenses should soon be a thing of the past.

Spectacle-mounted ocular display apparatus

Abstract: Spectacle-mounted display apparatus in which a reflective surface of a partially-transparent eyeglass lens is employed as the primary optical element. A concave spherical relay reflector is positioned inside the lens/eye cavity. The display ocular is an asymmetrical multi-axial virtual image magnifier which receives the object light on its relay reflector and thereby reflects the object light from the partially reflective surface of the spectacle lens to the wearer's eye to form a virtual image at infinity. In various embodiments of the invention, the ocular display apparatus is employed as a personal display of film, LEDs, fiber optics, CRT or electronic images generated for delivering data to a wearer as a virtual image at infinity.

Multielement stable resonators containing a variable lens

Abstract: A unified formulation for the analysis of linear stable resonators containing a lens of variable focal length, which represents the rod of a solid-state laser, and other intracavity optical systems is presented. The stability, the mode spot sizes, the dynamical stability, and the misalignment sensitivity are investigated, and general properties that are valid for any resonator are derived. Some important practical consequences for resonator design are discussed.

Millimeter-Wave Characteristics of Phase-Correcting Fresnel Zone Plates

Abstract: A focusing element called the phase-correcting Fresnel zone plate is described, and its characteristics are given when used in the millimeter-wave region for imaging or frequency filtering in place of a lens. Two versions are discussed, one where alternate concentric annular grooves are cut in a single piece of low-loss dielectric, and a second where two (or more) dielectrics are used in alternate concentric rings. For the latter case, an appropriate choice of parameters produces a design of constant thickness (i.e., a flat disk), named the "planar lens." Design formulas and curves, as well as measured results, are given for both types, and an analytical description is derived for the far-field patterns. Compared with lenses, zone plates are simpler to construct and have lower absorption loss, thickness, and weight.

Lens shutter camera including zoom lens

Abstract: A lens shutter type of camera is disclosed in which a zoom lens is positioned in a lens block (1) which has a sector gear (15) rotatably associated with the lens block and with a rotatable cam ring (14). The cam ring and sector gear are rotatable in a substantially constant axial position. A movable finder optical assembly (8) and a movable strobe assembly (9) are movable in association with movement of the zoom lens. The zoom lens is movable between an extreme telephoto position and an extreme wide angle position, as well a into a fully collapsed lens position beyond the extreme wide angle position and a macro or close-up photographing position beyond the extreme telephoto position. When the camera is in its macro mode, a prism (P1) is inserted into the finder optical assembly to correct for parallax; the strobe assembly is moved to change its illumination angle; and an optical wedge (4e) is pivoted into the path between a light receiver (4) and a light emitter (3e). A single cam plate (53) is provided to move the finder assembly and the strobe assembly. The photographic aperture (22b) can be selectively closed by barrier plates (31a) when the zoom lens is moved into its fully collapsed position. A light intercepting assembly (210) is provided for preventing light from entering the photographic optical assembly via cam grooves (20 and 21). This intercepting assembly includes a flexible code plate (90) which surrounds a peripheral portion of the cam ring (14) and which provides positional information relating to the position of the zoom lens.

Optical information reading apparatus

Abstract: A handheld reader for reading optical information such as a bar code contains a reading sensor. An image of the optical information is imaged by light reflected from the optical information, via a reflecting mirror, a lens and a diaphram member, onto the reading sensor so that the image is converted into an electric signal. A pair of LEDs are disposed on both sides of the image sensor so that the images thereof are imaged near the optical information by light from the LEDs through the diaphram member, the lens and the reflecting mirror. The LEDs and reading sensor are controlled so that the LEDs are disabled from emitting light while the reading sensor performs the reading operation of the optical information. Instead of LEDs, optical fibers can be used.

Theoretical approach to intraocular lens calculation using Gaussian optics.

Abstract: A computer-assisted method of calculating intraocular lens (IOL) power using formulas according to Gaussian optics is described. The method is more exact than current theoretical formulas, especially in calculating corneal power and in dealing with principal planes, and tends to give somewhat higher values for IOL power. One advantage of the theoretical approach is that the eye can be analyzed optically in a conventional manner, not only for the IOL power of emmetropia but also for the power of the biological lens, the total refractive power of the eye, and the magnification of the entire system. The relation to other theoretical formulas is discussed.

Optical beam integration system

Abstract: An improved optical beam integration system for homogenizing a nonuniform radiant energy beam having a nonuniform beam intensity profile characteristic. The optical beam integration system comprises a first crossed lenticular cylindrical lens structure, a second crossed lenticular cylindrical lens structure, and a focusing lens interposed between a radiant energy source and an image or work plane. The nonuniform radiant energy beam from the radiant energy source refracts sequentially through the first and second crossed lenticular cylindrical lens structures and the focusing lens so as to produce a homogenized beam which forms an image in the work plane. The work plane is at a constant distance from the optical beam integration system. Preferably, the optical beam integration system is adjustable for selectively setting the size of the image produced by the homogenized beam in the work plane. The optical beam integration system is also preferably adjustable so that the aspect ratio of the image produced by the homogenized beam in the work plane can be selectively set. As a result, the effectiveness and flexibility of semiconductor processing by means of an ultraviolet excimer laser, for example, are substantially improved.

Adjustable transparency spectacles

Abstract: Eyewear has variable transparency provided by a lens made of a non-diffusing dichroic liquid crystal cell with nematic-cholesteric phase change. A voltage source supplies an adjustable voltage to the liquid crystal cell; adjustment of the voltage to change the transparency of the lens is effected by a photocell which senses ambient light, or by manual control, or both.

Precision lens mounting

Abstract: A precision lens mounting assembly which includes a plurality of lens cells and a plurality of lenses which correspond to the plurality of lens cells. The lens cells have an annular shape. Flexure means are disposed within the inner diameter of the lens cell which hold the lens in a predetermined spatial relation at a datum temperature to the lens cell. The flexure means return the lenses to this predetermined spatial relation following temperature excursions away from, then back to, the datum temperature. The outer diameter of the lens cells in the assembly are all substantially equal and substantially concentric about the optical axis of the lenses they hold. The upper and lower surfaces of the lens cell each have three or more precision surfaces disposed on a plane. The planes are perpendicular to the optical axis of the lens and have a predetermined spatial relation to the apex of the lens. Selected ones of the lens cells can be rotated, translated or moved axially with respect to the other lens cells in the lens assembly to correct for astigmatism, coma or spherical aberrations, respectively. Adhesive means are provided to hold the plurality of the lens cells together.

Diode laser arrangement forming bright image

Abstract: A plurality of diode lasers is focussed onto a single region by arranging the diodes at equally spaced locations on a first arc. Each diode laser emits light in a slit-like pattern which is characterized by orthogonal axes. In a first group of cylindrical lenses, one associated with each diode laser, each lens has a refractive surface having an axis parallel to one of the emitting axes of the laser and refracts light to a focal region of defined dimensions. Each cylindrical lens is disposed along a second arc having a circular center common with the first arc. A second group of cylindrical lenses, one associated with each laser, is also disposed on a circular arc, concentric with the other arcs, but the second group has a refractive axis perpendicular to the first refractive axis. The second group of cylindrical lenses acts upon the second axis of the source image, focussing it to the common focal region. The first and second cylindrical lens groups may be combined into a toric surface within a single lens. The cylindrical lenses may either be individual lenses, or may be combined into a lenticular array. The lenses may be simple cylindrical refractive lenses, Fresnel lenses, or holographic lenses. A bright image of the source is formed at the common focal region. The diode lasers and cylindrical lenses may be arranged in three dimensions to produce very high optical power densities.

Apparatus for scanning and reading bar codes

Abstract: An improved bar code scanning and reading apparatus which is adapted to be hand-held utilizes anamorphic optics for scanning and reading the code by providing a beam having an oblong cross-section in the nominal plane of the code. The oblong cross-section may be aligned with the bars of the code. The optics does not focus the beam in the longitudinal direction of the cross-section at the nominal plane of the code so that diffraction effects which would otherwise cause rotation of the cross-section of the beam to a position transverse to the bars of the code which would preclude reading of narrow bars, is avoided. The last lens of the anamorphic system may be a cylindrical lens which provides a line focus of a visible marker beam while at the same time providing the oblong cross-section of the beam which scans the code. The light from the vicinity of the code passes through the cylindrical lens and is collected by a toric reflector which projects the incoming light onto a photodetector. Power for operating the source of the scanning beam (a laser diode) is conserved by an opto-electronic system responsive to the movement of the sectors of a rotating beam deflector (a polygon reflector) so as to enable power to be applied to the laser only during the intervals when the beam is disposed within the limits of its scan path.

Zoned multi-focal contact lens

Abstract: Bifocal contact lenses are described wherein at least the major viewing area is divided into a plurality of near and distant viewing zones, each near vision zone being adjacent to a distant viewing zone and there being between about 2 and 8 zones of each power in said major viewing area, each zone being capable of operating as a lens independently of the other zones and wherein the relative areas of the zones are such that in use substantially equal amounts of light enter the eye through the near and distant vision zones.

Illumination device using a laser

Abstract: An illumination device forms a secondary light source having N spots by vibrating a laser beam having a wavelength λ emitted from a pulsed laser by a vibration mirror having a swing angle θ 0 , and irradiates an object to be illuminated through a plurality of lens elements arranged at a spacing d. Those elements meet relations of d=m.(λ/θ.sub.0) N.(λ/θ 0 )>M.d where M is the number of lens elements in a predetermined array direction of the plurality of lens elements included in at least a spatial coherent area and m is any integer. Light intensity of the pulsed laser illumination is adjusted such that a total light intensity of the laser beam having pulses satisfying the above relations is equal to a light intensity required for the object to be illuminated.

Liquid crystal shutter array having microlenses corresponding to the pixel electrodes

Abstract: A liquid crystal shutter array requiring no separate focusing lens system Microlenses for focusing the light incident upon a matrix of pixel electrodes are formed in a transparent substrate of the shutter assembly A refractive index of light of each of the microlenses is set in a manner such that the incident angle θ of the light incident on the liquid crystal of the shutter through the microlenses satisfies; ##EQU1## where P, a, and d respectively represent the size of each of the photomasks, the length of a portion wherein each of the photomasks and corresponding ones of the pixel electrodes overlap, and the thickness of the transparent substrate on the light output side

Intraocular lens with converging and diverging optical portions

Abstract: An intraocular lens for patients having macular degeneration. The intraocular lens comprises a first portion including a diverging lens, and a second portion including a converging lens. The converging lens provides the patient with substantially the same vision he or she had prior to implantation of the intraocular lens, i.e., the decreased visual acuity normally associated with macular degeneration, while providing unmagnified and unrestricted peripheral vision. The diverging lens, when combined with converging lens means located outside the eye (e.g. a spectacle lens), provides a magnified retinal image of a given object with increased visual acuity but a restricted visual field. Thus, the intraocular lens of the invention provides the patient with the choice of unmagnified but peripherally unrestricted vision or magnified but peripherally restricted vision.

Ion Beam Lithography

Abstract: Apparatus and method for projection ion beam lithography are described which allow formation of low distortion, large field, reduced images of a mask pattern at a wafer plane using an optical column of practical size. The column shown is comprised of an accelerating Einzel lens followed by a gap lens, with numerous cooperating features. By coordinated selection of the parameters of the optical column, lens distortion and chromatic blurring are simultaneously minimized. Real time measurement of the position of the image field with respect to the existing pattern on the wafer is employed before and during the time of exposure of the new field and means are provided to match the new field to the existing pattern even when the latter has been distorted by processing. A metrology system enables convenient calibration and adjustment of the apparatus.

Rectangular-apertured micro-Fresnel lens arrays fabricated by electron-beam lithography

Abstract: Rectangular-apertured micro-Fresnel lens arrays are proposed. These lens arrays have been fabricated by an electron-beam writing system specially developed for the fabrication of microoptical devices. It is experimentally demonstrated that the lens arrays showed uniform focusing characteristics, and that each lens exhibited a diffraction-limited focusing characteristic with efficiency of 74%.

Optical microscope tomography. I. Support constraint

Abstract: A new principle of tomographic optical microscope imaging has been developed that uses a computerized reconstruction algorithm and a transmission optical microscope. A conventional transmission microscope with a rotationally oblique illumination system provides projections of a thick specimen in various directions within the numerical aperture of the objective lens. The images obtained are combined to reconstruct a three-dimensional distribution of the sample by inverting the imaging system in a computer. The three-dimensional optical transfer function of this projection system is analyzed, and it is found that this system is strictly angularly band limited. For improving the spatial resolution we utilize a priori knowledge of the spatial extent of the object as the support constraint. Experimental results are presented to demonstrate the tomographic imaging capability of this principle.

Variable power finder

Abstract: A variable power finder having an objective lens of positive refracting power comprising a first lens unit of positive refracting power movable along an optical axis and a second lens unit releasably attached to the first lens unit in axial alignment, wherein a real image to be observed is formed by the objective lens.

Variable focal length camera

Abstract: The present invention provides a bifocal camera capable of changing focal length of a photographic lens system and having lens drive means operable by a motor to switch the photographic lens system between a first focal length state wherein a main lens component is located at a rear position and a second focal length state wherein the main lens component is located at a front position and an auxiliary lens component is located at an operative position. This camera comprises a device for automatically stopping the motor when shifting of the main lens component is interrupted by force, and a device for restricting the shifting of the main lens component between the front position and the rear position. The auxiliary lens component is moved and a lens barrier is opened and closed in interlocked relationship with the shifting of the main lens component.

Coupler for ultrasonic transducer probe

Abstract: A coupler for use between an ultrasonic transducer probe and a sample to be examined thereby to keep the ultrasonic transducer probe and the sample spaced a prescribed distance from each other includes an acoustic lens in an area through which a ultrasonic signal is to pass from the ultrasonic transducer probe. The acoustic lens allows the focusing point of the lens of the ultrasonic transducer probe to be shifted to a desired position. Since the ultrasonic transducer probe and the sample are spaced from each other by the coupler, the image of an observed region of the sample can be positioned in a wide field of view on a screen.

Transmission and reception module for a bidirectional communication network

Abstract: A transmission and reception module for a bidirectional optical communication network characterized by a housing containing a laser diode, a first spherical lens for focussing the output of the laser diode on a first beam path, a second spherical lens arranged on the first beam path for focussing the light from the first lens at a focal point at which an end face of an optical fiber is positioned, a beam splitter which is at least partially transmissive to light of a first wavelength from the laser diode and partially reflective of light of a second wavelength being emitted from the fiber into a second beam path on which a detector is positioned. To improve the positioning, the first lens and the laser diode are mounted on a carrier member in a fixed relationship which enables assembling the device with less problems with maladjustment.

Objective for an endoscope

Abstract: An objective for an endoscope comprising, in the order from the object side, a first lens unit I having negative refractive power, a second lens unit II having positive refractive power, a third lens unit III having positive refractive power, an aperture stop S arranged between the front end of the second lens unit and rear end of the third lens unit and a fourth lens group IV comprising a lens component which has a concave surface on the object side, the four unit objective for an endoscope being arranged so that the overall length is short, outer diameter of the objective is small, angle of view is wide, intensity of light in the marginal portion is high, and distortion is corrected favourably.

High image resolution image pickup system with color dispersion means

Abstract: An image pickup system with an illuminating device capable of sequentially irradiating three kinds of color lights different from each other onto an object, an objective lens system forming images of the object with the color lights, a solid-state image sensor receiving the images of the object, a signal processing device producing individual color images of the object based on electric signals supplied from the solid-state image sensor, and a color dispersion device or a color separation device disposed in an optical path of light incident on the solid-state image sensor from the object. The color dispersion device includes the combination of variously shaped prisms and a diffraction grating, and the color separation device includes a structure compounded of dichroic mirrors, whereby the images with respective color lights are incident at positions shifted each other on the solid-state image sensor. The compound of signals indicative of individual color images makes it possible to bring about the object image with high resolution.

Plasma Focusing for High-Energy Beams

Abstract: We analyze the self-focusing effect of a relativistic electron or positron beam traversing through a thin slab of plasma in a linearized fluid theory, and show that the effect is very strong The idea of employing this effect for a plasma lens suggested by Chen is then reviewed The self-focusing force can be made uniform over the length of the beam by injecting an appropriate precursor Computer simulations on both thin and thick plasma lenses are presented, which show reasonable agreement with theoretical predictions