Showing papers on "Lens (optics) published in 1985"

Compact head-up display

Abstract: A compact head-up display comprising a combiner which combines light energy from an outside view with light energy transmitted within the combiner and diffracted out by means of an upper diffraction grating. The head-up display disclosed further comprises an image source, a collimating lens, and a lower diffraction grating for diffracting the collimated light energy into the combiner.

Variable power lens system.

Abstract: In one form the lens power may be varied (Fig 1) and in another the power may be selectively fixed in a carrier material (Fig 8) There are no moving mechanical parts but instead an optically active molecular material such as liquid crystals In one embodiment, the lens (72) and control means (60, 54, 58) for varying the power of the lens are mounted on a common substrate (70a) (Fig 3) The lens may be a single optical element (Fig 3) or a multi-element device such as a Fresnel lens (Fig 7a) A variable gradient index of refraction is achievable by applying a controlled stimulus field to the lens For example, a geometrically configured matrix of electrical voltages (52), each at a selected addressable location (78c) relative to the optically active material, provides the gradient in one embodiment (Fig 2) A thin film embodiment finds applications in magnifying glasses, cameras, telescopes, microscopes, as well as for intraocular and contact lenses for the human eye

Photolytic technique for producing microlenses in photosensitive glass

Abstract: A process is described whereby 2-D arrays of small diameter spherical lenses are produced in a homogeneous photosensitive glass by a photothermal technique. The mechanism of the lens formation is explained on the basis of the density change of the photonucleated microcrystalline phase developed relative to the unexposed glass. The lens formation is related to such variables as optical exposure, thermal schedule, glass thickness, and lens diameter. Optical characterization of the lenses produced by this technique was carried out by interferometric and MTF measurements. One-to-one conjugate erect imaging lens arrays were fabricated and tested.

Electronic display with lens matrix

Abstract: An electronic display includes a matrix of LEDs mounted to a circuit board and selectively operated to produce a message or image. A reflector matrix mounts to the circuit board and provides light pipes which extend forward from each LED to direct its light and provide protection. Potting compound is disposed in each light pipe and extends beyond the reflector matrix to provide a convex lens. In one embodiment the potting compound extends into a convex lens cover.

Head-up display for automobile

Abstract: A head-up display for use in an automotive or other vehicle having limited space. The optical path from display symbol generator to a collimating lens is folded to fit in a relatively compact housing. Also shown is the use of the automobile windshield as a combiner glass for the display. Corrective lenses, and in particular crossed linear fresnel lenses, are used to correct for the astigmatism introduced by the geometry of the windshield. This provides a combination of optical powers for the display lens and the windshield which has the resultant effect of projecting an image from the image source to the driver's eye. The source is a high light output array of light-emitting diodes. A microprocessor based controller for detecting the status of inputs from the automobile is shown. Data is periodically loaded into a random access memory dedicated to controlling the display. When data is not being loaded, a separate address and timing generator is used to cause data from this memory to be displayed in a free-running mode.

Talbot interferometry for measuring the focal length of a lens.

Abstract: A method for measuring the focal length of lenses using the Talbot effect and the moire technique is described. The test lens is placed in front of a set of two gratings. The first grating illuminated by the light passing through the test lens produces the magnified Talbot image. The moire fringe is generated by superimposing this Talbot image on the second grating. The tilt angle of the moire fringe is a measure of the focal length of the lens. In the experiments, the focal lengths of positive, negative, and power-distributed lenses are measured.

Focus detecting device

Abstract: PURPOSE:To detect a focal shift with high sensitivity by providing two photoelectric detecting means each having a non-photosensitive body part of the almost same shape as a spot optical image, on a part of the photodetecting surface by shifting them from the image forming surface separated by a half mirror. CONSTITUTION:A luminous flux from a light source 1 is made parallel by a lens 2, reflected by a half mirror 3 and made to form an image on a data 5 by a lens 4. Its reflected light is divided into two by a half mirror 8 through the lenses 4, 7, provided onto glass plates 9a, 10a having circular light shielding parts 9b, 10b, and photoelectrically converted 9, 10. Glass plates 9, 10, for instance, are shifted by (d) forward and backward from surfaces FP1, FP2 on which the reflected light is to be focused. Output of the detectors 9, 10 are amplified by a circuit which is not shown in the figure and denoted as A and B, A+B and A-B are derived and a division (A-B)/(A+B) is executed, and the lens 4 is moved forward and backward by driving a motor 12 so that said value becomes minimum. In such a way, the focusing which is precise and has high sensitivity is executed. It is suitable for observing a pattern of a mask or a wafer.

CRT magnifying lens attachment and glare reduction system

Abstract: A CRT magnifying lens attachment and glare reduction system for use with a computer display screen. The attachment supports the magnifying lens and glare reduction system adjacent the display screen. The magnifying lens and glare reduction system includes at least on fresnel lens positioned adjacent an optical element, the optical element reduces glare and enhances the image produced by the screen.

Pulsed laser damage to optical fibers.

Abstract: This paper describes some observations of pulsed laser damage to optical fibers with emphasis on a damage mode characterized as a linear fracture along the outer core of a fiber. Damage threshold data are presented which illustrate the effects of the focusing lens, end-surface preparation, and type of fiber. An explanation based on fiber-beam misalignment is given and is illustrated by a simple experiment and ray trace.

Delivery system for high-energy pulsed ultraviolet laser light

Abstract: The density of the energy that is conducted within a fiber-optic waveguide (12) is increased by means of an energy coupler (30, Figures 3 and 4) at the input end of the optical fiber (12). This energy coupler comprises a fused or ground lens (46) at the input end of a silica-based fiber (12). A second lens (47), preferably a plano-convex lens, focusses a large collimated laser beam to a point source (48). The lens (46) at the end of the fiber (12) is located at a distance greater than the focal length of the second lens (47), so as to receive light from the point source (48) and couple it into the fiber (12).

Ophthalmic glass/plastic laminated lens having photochromic characteristics and method of assembly thereof

Abstract: A composite glass/plastic ophthalmic lens is disclosed. The lens consists of a thin layer of glass, preferably photochromic, adhered to the front of a plastic layer, by a highly elastic adhesive. The rear surface of the glass has a different radius than the front surface of the plastic so that the space between the lenses forms a tapered gap which is filled by the elastic adhesive. The edge thickness of the elastic adhesive is sufficient to insure that the increase in diameter of the plastic layer with respect to the diameter of the glass layer due to differences in the thermal expansion characteristic of the glass and the plastic will not damage the composite lens even over a temperature range greater than 300° F. The glass layer is shaped to have a power which compensates for differences in the index of refraction of the glass, adhesive and plastic layer, and which compensates for the optical powers produced by the tapered adhesive layer, so that the composite lens can be finished to prescription as though it were an all-plastic lens.

Fish eye lens system

Abstract: A high performance medium speed fish eye lens system is provided, capable of compensating all aberrations except the distortion at an aperture ratio of at least 1:4.2. The lens system consists of a first lens group (G1) of negative refractive power including two negative lenses curved towards the object, a middle positive lens component (G2) curved towards the object, which lens component can be composed of a cemented doublet, and a last lens group (G3) of positive refractive power consisting of a cemented doublet or a cemented doublet and an additional positive single lens both curved towards the image.

Variable-Focus Liquid-Crystal Fresnel Lens

Abstract: Liquid-crystal lens-cells shaped like a plano-convex Fresnel lens with homogeneous alignment are prepared. Their focal length can be varied from the value fe for an extraordinary ray to nearly fo for an ordinary ray by applying an electric field across the cell. The response and recovery times within several seconds are attained in the liquid-crystal lenses. More transparent (\gtrsim80%) variable-focus liquid-crystal lenses are achieved in the double-layered structure of two identical liquid-crystal Fresnel lenses with a mutually orthogonal optic axis.

Optical information reader

Abstract: PURPOSE:To eliminate the use of an optical system which converts the form of luminous flux to reduce the weight of a reader and at the same time to facilitate positioning of a photodetector, by obtaining a focusing error signal from the variation of reflection factor at a level close to a critical angle after combining a diffraction grating with a parallel plate. CONSTITUTION:When parallel beams 17 are made incident vertically on the 1st boundary surface 13 of a parallel plate 13, the beams 17 transmit through the 2nd boundary surface 13b of the plate 13 and are made incident on a diffraction grating 15 to be diffracted there. The diffracted beam 18 is made incident again on the surface 13b and travels straight to reach a point P. The constant of the grating 15 is decided so that the incident angle at the point P is equal to the critical angle of total reflection. Therefore the beam 18 is totally reflected at the point P and made incident on a photodetector 11. The beam 18 is totally reflected if the angle theta is larger than the critical angle thetaS; while the beam 18 transmits partially through the surface 13a if the angle theta is smaller. When a disk 7 gets close to an objective lens 6, the light made incident on the grating 15 is turned into the dispersed luminous fluxes. Then the luminous flux has a semicircular form and is made incident only on a photodetector 11b. While the incident light of the grating 15 is focused when the disk 7 goes further away from the lens 6. Then the luminous flux has a semicircular form and is made incident only on a photodetector 11a.

Testing aspheric surfaces with computer-generated holograms: analysis of adjustment and shape errors.

Abstract: Various interferometric methods can be used for testing aspheric surfaces with high accuracy. Using a partially compensating lens in a Twyman-Green arrangement together with a computer-generated hologram instead of a null corrector gives great flexibility. For quantitative analysis a high-resolution automatic fringe analysis is necessary. The interferometric arrangement and the setup for the interferogram data acquisition are described along with different algorithms for calculating the wave front data. Tilt and decentering of the aspheric surface and the synthetic hologram as well as the actual aspherical parameters can be derived from the calculated wave front using Zernike polynomials to communicate with a ray tracing program. For small adjustment and shape errors the linearity will hold, leading to fast correction and numerical compensation of their effects on the surface error. The method is verified by several examples. Experimental results agree with the proposed model.

Apparatus and method for optical guidance system for automatic guided vehicle

Abstract: An optical guidance system for remotely controlled, self-propelled vehicles in which a single light source is used as an aiming point by the vehicle. The light source is detected by a camera lens and the vehicle is maneuvered according to the position of the light within the field of view of the lens. A computer is provided to determine the cartesian coordinates of the light source and calculate the position of the vehicle relative to the light source. The light source also transmits optically coded information for controlling the vehicle relative to the position of other vehicles, the condition of the vehicle path or other related information.

Methods and apparatus relating to photovoltaic semiconductor devices

Abstract: A solar concentrator-photovoltaic module having a matrix of miniaturized photovoltaic cells is formed by using a laser beam to form the miniaturized photovoltaic cell sites in situ. A laminated sheet is formed by a light-transmissive lens sheet having a matrix of lenses, and a substrate including a conductor layer formed onto the bottom side of the lens sheet. The laminated sheet is then irradiated using laser beams directed normal to and through each lens of the lens sheet, to perforate the substrate including the conductor layer forming cell sites. Cells can be formed in situ by applying an amorphous or multi-crystalline semi-conductor material to the cell sites from the bottom of the laminated sheet. The laminated sheet is then irradiated further with laser beams directed through each of the lenses, to thereby convert the amorphous material to a properly doped and fully crystalline photovoltaic junction. The bottom of the laminated sheet is then coated with final lower conductive and sealing layers to protect the laminated sheet from environmental effects.

Liquid crystal lens having a variable focal length

Abstract: A liquid crystal lens having variable focal length includes a cell in which a liquid crystal (6) is confined. The magnitude of a voltage applied across the liquid crystal may be changed to control the focal length of the lens. The cell is defined by transparent plates (1, 2), at least part of which is formed of a photochromic material or a material which acts as a barrier to harmful rays. In this manner, the amount of transmitted light can be controlled reversibly in accordance with the amount of incident light so that harmful rays, such as ultraviolet rays, infrared rays or dazzling rays can be filtered out. The filter may comprise an acrylic resin with neodymium, or a separate liquid-crystal cell.

Unipotential electrostatic lenses: Paraxial properties and aberrations of focal length and focal point

Abstract: An experimental study of electrostatic electron lenses as a function of geometrical and electrical parameters is described. The lenses are of the symmetrical three‐electrode unipotential type. The parameters are the thickness of the center electrode and the interelectrode spacing, both relative to the center electrode aperture diameter, and the ratio of lens voltage to cathode voltage. The lens properties are characterized in terms of the focal length and focal distance, and the spherical and chromatic aberrations of these quantities. In general, the principal surfaces of a lens are not plane, and the aberrations of focal length and focal distance are not the same. Expressions are derived relating the focal length and focal distance aberrations to the spherical and chromatic imaging aberration coefficients Cs and Cc, and the magnification aberrations. The advantages of formulating the lens properties in terms of focal length and focal distance and their aberrations, and the usefulness of the data presente...

Display including a prismatic lens system or a prismatic reflective system

Abstract: A display comprising means for selectively scattering or transmitting light in response to a prescribed input and a prismatic lens means located on a non-viewing side of said scattering or transmitting means for focusing light onto a light absorbing surface to enhance the contrast of the display. Alternatively, a prismatic reflector means may be utilized to direct light toward a light absorbing surface.

In vivo assessment of lens transmission for blue-green light by autofluorescence measurement.

Abstract: A simple quantitative and reproducible method for evaluating lens transmission (λ = 490 and 530 nm) is described. It is based on the measurement of autofluorescence in the anterior and the posterior p

Fiber optic connector

Abstract: An optical fiber lens-connector assembly includes a plastic lens body joined to a tubular connector of a low thermal expansion glass. The connector includes a glass fiber guide formed of the same material (e.g., a borosilicate glass) having a substantially similar expansion coefficient. The assembly provides greater temperature stability when cycled over a wide temperature range. Fused silica quartz can also be employed as the connector material.

Pigment colored contact lenses and method for making same

Abstract: Colored contact lenses are produced by providing a contact lens constructed of polymer and coating at least a portion of the lens with coloring substance and binding polymer. The lens and binding polymers are bonded to each other by the reaction of functional groups selected from at least one of --COOH, --OH, and --NH--R, wherein R is hydrogen or alkyl, with functional groups selected from at least one of --NCO and epoxy.

Three dimensional imaging device

Abstract: An imaging device employs a known bidimensional, position sensitive light detector of the CCD type A converging lens system images points on a target surface onto the detector to generate data on the X and Y coordinates of each point The invention is characterized by a mask located in the aperture plane of the lens system This mask either has a pair of spaced apart, separate, circular apertures or an annular aperture symmetrical about the optical axis In the first instance, the result is to form spaced-apart dots on the detector for each point of the target surface, the distance between these dots being a measure of the Z coordinate of the respective point When using the annular aperture, rings are formed on the detector, the ring diameter representing the Z data The arrangement provides a compact and robust device for obtaining three dimensional data on a target surface

Posterior-chamber intraocular prosthetic lens

Abstract: A posterior-chamber intraocular prosthetic lens includes an optical lens (1) and two diametrically opposite supporting elements (2), each of the supporting elements (2) being shaped as a curvilinear body one of its lateral surfaces being convex and facing with its convex portion (3) in a direction opposite to the lens principal plane, while the other lateral surface of the body is cancave and faces with its concave portion (4) toward the lens (1) principal plane; the ends of the supporting elements (2) are rounded off and face each other, while the supporting elements (2) are spatially turned away from each other with respect to the principal plane of the optical lens.

Aspherical lenses produced by a fast high-precision replication process using UV-curable coatings

Abstract: Diffraction-limited aspherical lenses for audiodisc systems have been produced in a high-precision lens replication process using UV-polymerizable coatings. The requirements and merits of this process are described. The optical performance of the lenses is determined by the accuracy of the replication process and the physical properties of the photopolymerized coating. The optical and mechanical behavior of the replication coating is examined in detail over a broad temperature range.

Optical system for endoscope

Abstract: An optical system is disclosed for an endoscope having a generally tubular distal end in which an objective lens assembly and an image sensor in the form of a solid-state video camera are internally housed so that an image formed by the lens assembly is focussed upon the input or pickup surface of the video camera. The video camera is disposed along or in proximity to the center axis of the distal end of the endoscope and in some instances is oblique with respect to the center axis. The video camera may be positioned in this way due to the provision of a reflecting surface which is angularly disposed in opposing relationship with an input surface of the video camera, and deflection means disposed in front of the lens assembly and within the objective lens assembly, or between the lens assembly and the reflecting surface so that an image formed by the lens assembly can be focussed on the input surface of the video camera.

Realization of First Order Optical Systems Using Thin Lenses

Abstract: A first order optical system is investigated in full generality within the context of wave optics. The problem is reduced to a study of the ray transfer matrices. The simplest such systems correspond to axially symmetric propagation. Realization of such systems by centrally located lenses separated by finite distances is studied. It is shown that, contrary to the commonly held view, the set of first order systems that can be realized using axially symmetric thin lenses exhausts the entire SL(2, R) group; at most three lenses are needed to realize any element of this group. In particular, the inverse of free propagation can be so realized. Among anisotropic systems it is again shown that every element of the lens group Sp(4, R) can be realized using a finite number of thin lenses.

Semiconductor wafer scanning system

Abstract: A semiconductor wafer scanning system includes a confocal optical imaging system with a laser beam being focused on a small spot on the wafer surface to be scanned. The optics include an objective lens located closest to the wafer with means being provided to vary the spacing of the lens from the wafer over small distances to thus change the focal plane of the system. The wafer may be independently driven in two orthogonal directions in a plane generally perpendicular to the imaging system to bring selected portions thereof into view of the optics. During scanning, the wafer is rapidly vibrated in one of the directions while it is slowly moved in the other direction with a series of digital output signals being provided by the light reflected back from the laser spot on the moving wafer to provide precise information for constructing a three dimensional representation of the surface pattern of the wafer.