Showing papers on "Lens (optics) published in 1992"

Single lens stereo with a plenoptic camera

Abstract: Ordinary cameras gather light across the area of their lens aperture, and the light striking a given subregion of the aperture is structured somewhat differently than the light striking an adjacent subregion. By analyzing this optical structure, one can infer the depths of the objects in the scene, i.e. one can achieve single lens stereo. The authors describe a camera for performing this analysis. It incorporates a single main lens along with a lenticular array placed at the sensor plane. The resulting plenoptic camera provides information about how the scene would look when viewed from a continuum of possible viewpoints bounded by the main lens aperture. Deriving depth information is simpler than in a binocular stereo system because the correspondence problem is minimized. The camera extracts information about both horizontal and vertical parallax, which improves the reliability of the depth estimates. >

Optical scanning head

Abstract: The optical scanning head includes at least one trio of light emitting diodes arranged so the LEDs emit light at different angles to create a fan of light. An optical module includes a light shield or "dark room" and a lens/filter assembly which provides control of the depth of focus of the scanner. The optical module is located behind the light source, and the detector, made up of a CCD array is mounted behind the optic module for detecting the light intensity in the reflected beam over a field of view across a bar code symbol. The CCD array generates an electrical signal indicative of the detected light intensity. A DC source or battery provides DC voltage to the LEDs and CCDs in response to a clocked signal which provides a gradual or sequential illumination of the LEDs and coordinates the activation of the CCDs in order to minimize power consumption during scans.

High-speed optical coherence domain reflectometry.

Abstract: We describe a high-speed optical coherence domain reflectometer. Scan speeds of 40 mm/s are achieved with a dynamic range of >90 dB and a spatial resolution of 17 μm. Two applications are presented: the noninvasive measurement of anterior eye structure in a rabbit inυiυo and the characterization of reflections and interelement spacing in a multielement lens.

zoom lens system

Abstract: A zoom lens system includes a negative first lens group and a positive second lens group. The negative first lens group includes a negative lens element and a positive lens element. The positive second lens group includes a positive lens element, a negative lens element, and a positive lens element. At least the object-side positive lens element and the negative lens element are cemented together. The zoom lens system of the present invention satisfies the following conditions: 1.5 1 wherein f2G: the focal length of the positive second lens group; mW: the lateral magnification of the positive second lens group at the short focal length extremity; and mT: the lateral magnification of the positive second lens group at the long focal length extremity; fT: the focal length of the entire zoom lens system at the long focal length extremity; and fW: the focal length of the entire zoom lens system at the short focal length extremity.

Double-slot antennas on extended hemispherical dielectric lenses

Abstract: An investigation of the coupling efficiencies to a gaussian-beam of a double-slot antenna on a hyperhemispherical lens is presented. It is shown that both lenses couple equally well to an appropriate gaussian beam (about 80 percent). The radiation patterns of both lenses with a double-slot antenna are computed using the ray-tracing method. The experimental radiation patterns are presented and show close agreement to the theoretically computed patterns.

Using light as a lens for submicron, neutral-atom lithography.

Abstract: We show that light can be used as a lens to focus a collimated neutral atomic beam to submicron dimensions during deposition onto a substrate. We have used an optical standing wave at 589 nm as an array of cylindrical lenses to focus a perpendicular sodium beam into a grating on a substrate, with a periodicity of 294.3\ifmmode\pm\else\textpm\fi{}0.3 nm. This result is the first direct evidence of submicron focusing of atoms by light, and represents a fundamentally new scheme for submicron lithography.

Intelligent electro-optical system and method for automatic glare reduction

Abstract: An electro-optical system and method are disclosed for modulating the intensity of light rays propagating towards an optical element, such as an eye, a lens or aperture stop in a camera station, a camera station in a machine vision system, or other image detection device. The electro-optical system comprises an electro-optical element having a optically transparent surface having electrically addressable pixels. Each pixel has a light transmittance which is controllable by a controller that is operably associated with a computer system. An image acquisition device, such as a camera station, acquires an image of a spatial scene within the field of view of the optical element. The computer system processes the image to determine which pixels are to be addressed and actively driven in order to modulate (i.e. decrease) the intensity of incident light rays propagating through the determined pixels, towards the optical element. Illustrated uses for the present invention include glare and spatial noise reduction in the automotive, navigational, robotic and recreational arts.

Modern lens design

Abstract: Chapter 1: Introduction Chapter 2: Automatic Lens Design: Managing the Lens Design Program Chapter 3: Improving a Design Chapter 4: Evaluation: How Good Is This Design? Chapter 5: Lens Design Data Chapter 6: Telescope Objectives Chapter 7: Eyepieces and Magnifiers Chapter 8: Cooke Triplet Anastigmats Chapter 9: Split Triplets Chapter 10: The Tessar, Hellar, and Other Compounded Triplets Chapter 11: Double-Meniscus Anastigmats Chapter 12: The Biotar or Double-Gauss Lens Chapter 13: Telephoto Lenses Chapter 14: Reversed Telephoto (Retrofocus and Fish-Eye) Lenses Chapter 15: Wide-Angle Lenses With Negative Outer Elements Chapter 16: The Petzval Lens: Head-up Display Lenses Chapter 17: Microscope Objectives Chapter 18: Mirror and Catadioptric Systems Chapter 19: Infrared and Ultraviolet Systems Chapter 20: Zoom Lenses Chapter 21: Projection TV Lenses and Macro Lenses Chapter 22: Scanner/f-o, Laser Disk and Collimator Lenses Chapter 23: Tolerance Budgeting Chapter 24: Formulary GLOSSARY REFERENCES INDEX

Apparatus and a method for high numerical aperture microscopic examination of materials

Abstract: Apparatus and a method for performing high resolution optical imaging in the near infrared of internal features of semiconductor wafers uses an optical device made from a material having a high index of refraction and held in very close proximity to the wafer. The optical device may either be a prism or a plano-convex lens. The plano-convex lens may be held in contact with the wafer or separated from the wafer via an air bearing or an optical coupling fluid to allow the sample to be navigated beneath the lens. The lens may be used in a number of optical instruments such as a bright field microscope, a Schlieren microscope, a dark field microscope, a Linnik interferometer, a Raman spectroscope and an absorption spectroscope.

Spatial and temporal transformation of femtosecond laser pulses by lenses and lens systems

Abstract: A Fourier-optical analysis of the transformation of ultrashort light pulses by lenses is given. Inserting the material dispersion up to second order, we find a coupling between the temporal, spectral, and spatial properties of the light pulse. In general, this coupling leads to a drastic increase in pulse duration and width of the spatial intensity distribution in the focal plane of the lens, which can be avoided with the use of achromatic lens doublets. The results are discussed for Gaussian-shaped input pulses.

Contoured duct apparatus and method for insertion of flexible intraocular lens

Abstract: An apparatus and associated method for deforming and inserting a flexible intraocular lens into an eye which permits the size of an ocular incision to be significantly smaller than the diameter of the intraocular lens being implanted, and its embodiments are suitable for use with lenses having radial flange or projecting filament haptics. The apparatus includes a contoured duct with a pair of internal guiding grooves configured to engage peripheral edges of the lens, curling the lens as it is advanced along the longitudinal duct axis from the elongated inlet to the coaxially aligned generally circular outlet of the duct. The guiding grooves are mutually opposed and converge along the length of the duct to essentially the periphery of the duct outlet. A lens is implanted utilizing this apparatus by loading the lens into a receiving chamber adjacent to the lens-curling contoured duct, inserting the outlet or a cannular probe communicating coaxially with said outlet into the ocular incision, and advancing the lens through the duct and then through the outlet into the eye.

Semiconductor insulation for optical devices

Abstract: A method and apparatus for enclosing an optically active integrated circuit die mounted on a region of a printed circuit substrate within either a unitary optical plastic lens element and enclosure or a discrete lens element and enclosure formed with mechanical standoff tabs and positioning pins for attaching and securing the unitary or discrete enclosure to the circuit substrate. The mechanical tabs of the enclosure have catches that snap in place into receiving apertures in the substrate so as to position the molded plastic lens over the optically active integrated circuit device at a predetermined distance providing the desired focal length. The molded plastic lens of the optical plastic enclosure protects the optically active integrated circuit from damage and images light thereon or therefrom. In a preferred embodiment, the side walls of the plastic enclosure contact the surface of the substrate and enclose the die and the region that the die is mounted on. The remaining volume enclosed within the molded plastic enclosure and lens element may be filled with a transparent epoxy material to provide a unitary, sealed enclosure with the optically active integrated circuit die with the region on the substrate. Preferably, the optically active device is a photosensitive micro-electronic circuit element, e.g. a photosensor or a charge coupled device (CCD).

Two path liquid crystal light valve color display with light coupling lens array disposed along the red-green light path

Abstract: A full color, liquid crystal display device is disclosed having two optical paths, the first for long (red) and medium (green) wavelength regions of the visible light spectrum, and the second for the short (blue) wavelength region of the visible light spectrum. The two optical paths and their properties are nominally matched to the characteristics of the chromatic and luminance processing channels of the human visual system. The two-path device generates two separate, spatially coherent color images using two liquid crystal light valve image forming sources, without the use of color filters typically found in full color displays. The two images are combined by additive spatial superposition to produce a single, full-spectrum, composite color image. In one embodiment, individual red and green light components from an efficient, patterned backlight of individual red and green light emitters are coupled by a light coupling lens array to respective display pixels in the liquid crystal light valve. In another embodiment, red and green light components form a red and green image by passing through two aligned liquid crystal light valves and two color selecting polarizers. A light coupling lens array couples the light from one liquid crystal light valve to the other. Suitable light coupling lens arrays in both embodiments include a SELFOC lens array, a strip lens array, or a microlens array. The composite image may be either directly viewed or optically projected using a conventional projection lens assembly onto an intermediate viewing surface.

Modeling the power of the aging human eye.

Abstract: A hypothesis is presented that may explain why the aging eye does not become myopic with age. The power of the eye lens is predicted with a modeling approach to determine how the form of the refractive-index gradient within the lens can change to maintain a constant power in spite of age-related curvature increase. Methods used include published age-dependent data on the optical parameters of the eye, a mathematical model of the lens based on elliptical isoindicial contours, and a refractive-index profile that can be expressed as a power series in the distance from the lens center. The kinds of change in profile required to prevent the eye from becoming myopic as its lens grows are shown.

Femtolensing of gamma-ray bursters

Abstract: If gamma-ray bursters are at cosmological distances, they can be used to probe for «femtolenses» extremely small (∼10 −13 -10 −16 M ⊙ ) dark-matter objects. The time delay induced by such a lens would be ∼10 −17 -10 −20 s, approximately equal to the period of a gamma ray. Interference between the two images would induce a characteristic interference pattern as a function of detected frequency. The pattern would be stable on time scales of 1 s, but might slowly drift on time scales of 10 s in response to the relative motion of the lens and source

Risks of Keratitis and Patterns of Use With Disposable Contact Lenses

Abstract: • Disposable soft contact lenses have been marketed as a safer alternative to conventional soft lenses. We undertook a casecontrol study of patients attending the casualty unit of an eye hospital to quantify the relative risk of keratitis in disposable lens wear and to establish associated patterns of use. All eligible contact lens users were identified and asked to complete a questionnaire (n=242). Keratitis, microbial or sterile, was the most common complication in disposable lens users, occurring in 16 of 41 subjects. The relative risks for all lens types were estimated by comparison with rigid lenses (the referent). Both extended- and daily-wear disposable lenses were associated with higher risks of keratitis than other lens types including conventional extended-wear lenses. Poor hygiene, disinfectant system failure, and lens type may all account for these statistically significant trends.

Focus detection device

Abstract: PURPOSE:To realize simple constitution and reduce the size of a camera body by using a holographic optical element as a means which guides luminous flux to photodetecting elements when focus detection is performed by using the phase difference between the light intensity distributions of two pieces of luminous flux passed through the same optical system. CONSTITUTION:The luminous flux exiting from a photographic lens 1 is made incident on the holographic optical element 17 and split into transmitted light of 0th order and diffracted light and although the transmitted light of 0th order is imaged on an image pickup surface 5, the diffracted light forms images I5 and I6 on the photodetecting elements 11. When the image formation plane of the luminous flux exiting from the lens 1 is on the object side about the image pickup surface 5, the position where the light is made incident is closer to the optical axis of the lens 1 than in focusing. When the image pickup surface 5 is on the body side about the image formation plane, the position is far. Namely, the interval between both the images I5 and I6 is detected by arithmetic processing from the brightness distributions on the elements 11 to detect the focusing state of the lens 1 including a front-focus and a rear-focus quantity.

Distance measuring method and a distance measuring apparatus

Abstract: Method and apparatus for obtaining distance data from an object to a lens by obtaining an image of the object by an image input unit for forming an image of the object through the lens on an image receiving plane. Two observed images Is and Is' with different blurs from the image input unit are obtained by making a position of the lens and/or a position of the image receiving plane with regard to the object different by a minute distance Δz. A filtering process is then performed by applying a filter to the two input observed images Is and Is', thereby providing two output images Fs and Fs'. The distance a up to the object is calculated by using the two output images Fs and Fs' obtained by the filtering process based on the relation between the two output images Fs and Fs' and radius s of the blur and the distance a from the lens to the object.

Corneal inlay lenses

Abstract: A low or high refractive index corneal inlay optical lens adapted to be inserted singly or multiply between the layers of a cornea to correct refractive errors in eyesight, wherein the implanted lens is a solid transparent uncoated lens having no apertures therethrough, of a diameter less than that of the optic zone of the eye under normal light or bright light conditions, such that the movement of fluids, nutrients and gases throughout the corneal layers is unimpeded, and wherein the composition of the lens or lenses relative to that of the surrounding stromal tissue are such that multiple refractive indices may be created and multiple focal corrections are possible.

Stereo video endoscope objective lens system

Abstract: A stereoscopic objective lens system for video endoscopes and borescopes includes a full diameter collimator lens system (110, 112) and a pair of half-diameter stereo lens systems (114, 116, 118, 120). The lens systems can be formed of doublet lenses (312) or a combination of singlet (310, 313) and doublet lenses (312, 314, 318), or of gradient index lenses (210, 214, 216) or of a mixture of such lenses. The full-diameter lens system collimates object points, imaging object points to infinity to present equal-angle pairs from symmetrically disposed object points to the small stereo pair. This equal-angle property enables accurate object/image mapping onto the final stereo image pair, such that all parts of each left/right image can be mapped to within a fraction of a video pixel to each other.

One-piece bifocal intraocular lens construction

Abstract: A rigid bifocal intraocular lens (60) for use as an artificial lens implant is disclosed. In one embodiment, the intraocular lens has a rigid lens body (61) having a chord (61a) and first and second lens portions (62) and (63). The first lens portion (61) has a focal length and the second lens portion (63) has a focal length different from the focal length of the first lens portion (62). The first lens portion (62) is positioned on one side of the chord (61a) and the second lens portion (63) is positioned on the other side of the chord (61a). The first and second lens portions (62 and 63) form an integral, one-piece optical lens body (61) with the first and second lens portions being non-movable with respect to one another. In another embodiment the rigid lens body has a first central circular lens portion and a second outer annular lens portion. In a preferred form of this embodiment the inner, circular lens has a diameter of a between about 1.8 millimeters and about 2.0 millimeters, with the outer annular lens portion having a diameter of between about 6 millimeters and 7 millimeters. A preferred corrective power for the lenses used in the above-referenced embodiments is between about +15 and about +25 diopters for a distance-viewing lens portion, and a corrective power for a near-viewing portion of between about +3 and +4 diopters greater than the corrective power of the distance-viewing portion. Preferably, the lens portions are formed from molding in a manner avoiding introduction of any substantial refractive index gradient in the lens material.

Treatment of Ocular Surface Disorders and Dry Eyes with High Gas-Permeable Scleral Lenses

Abstract: Extreme corneal surface disorders and dry-eye conditions cannot be adequately treated with corneal contact lenses. For these cases a scleral lens with a diameter of between 21 and 25 mm could be prescribed. In this study, high oxygen-permeable scleral contact lenses were fitted onto 50 eyes, of which 32 had a deviant corneal topography and 18 had dry-eye syndrome. A significant improvement of visual acuity and good lens tolerance were found. The large lens successfully created a moist atmosphere in front of the cornea with dry-eye circumstances. No signs of oxygen shortage were recorded. In three dry eyes (16.7%) immediate failure in fitting was found, due to lens binding. The new scleral lens provides a physiological condition of the cornea, which allows a revival in the application of such lenses.

Electronic endoscope apparatus

Abstract: PURPOSE:To obtain an electronic endoscope which can prevent a patient from feeling a pain when a photographing head portion is inserted in a coelom of a patient by providing a photographing head portion having a solid state image pickup element and an enclosure for sealing a signal processing means, at least a part of which is formed by a light transmitting member, and an image monitor portion separated from the photographing head portion. CONSTITUTION:A photographing head portion 11 is constructed so that an objective lens 3, a solid state image pickup element 1, an image processing circuit element 7, a transmitting integrated circuit element 6, a light emitting element 4, and a battery 8 are stored in a capsule-like package 10. It is suitable to form the capsule-like package 10 by glass or plastics because it is hard to be dirty in a coelom and it is easy to photograph an image of an observed body. A 1.6X10 picture element CCD chip which is a charged coupling element is used as the solid state image pickup element 1. The objective lens 3 and an optical lens 3' are fitted to a glass plate. The former is for illumination and the latter is for photographing. The photographing head 11 is inserted in the coelom, an image signal is received by a receiver disposed outside the body, and the image is displayed on an image monitor 16 to observe the interior of the coelom.

Ccd solid state imager

Abstract: A flattened layer (6) formed between a micro-condenser lens (7) and an Al light-shielding layer (5) is formed as a bilayer and this bilayer is formed by sequentially laminating a first layer (6a) and a second layer (6b) having a refractive index (N₂) lower than a refractive index (N₁) of the first layer (6a). Therefore, of the incident light converged by the micro-condenser lens (7), a light component shielded by the shoulder portion of the Al light-shielding layer (5) is reduced and a sensitivity increasing effect, which is an effect inherent in the condenser lens, can be demonstrated sufficiently, which can make the CCD solid state imager compact in size and which can improve the image quality.

Optical device having a microlens and a process for making microlenses

Abstract: An optical device having a lens substrate and a microlens portion formed thereon, wherein the microlens has its lens portion formed on the part of the optical device that has substantially the same coefficient of expansion as that of the lens substrate.

Visual display system and exposure control apparatus

Abstract: A visual display system in which light from a light source is modulated by a space light modulator having a plurality of controllable elements arranged in a line and the modulated light is scanned by an optical scanning device to display an image. An exposure control apparatus having a lens, a photoelectric conversion device, and a space light modulator, wherein the space light modulator is operated to vary the amount of light to be supplied to the photoelectric conversion device, thereby controlling the exposure for the image focused by the lens.

Guiding and focusing neutron beams using capillary optics

Abstract: A METHOD for focusing X-rays by means of internal reflection inside hollow glass capillaries1–3has also been shown to be capable of guiding a neutron beam4 and now a neutron lens using this principle has been demonstrated5,6Here we study the properties of multiple capillary fibre bundles by measuring the transmission efficiency as a function of bending radius. The fibres used are shown to bend a neutron beam through 20° in a distance of 130 mm, with a transmission of 50%. A simple device made of a few fibres is used to demonstrate the focusing of cold neutrons (wavelength 0.2–0.9 mm) down to a 1-mm2spot size. These investigations will form the basis for the design of a neutron lens for use in materials research, or a beam bender capable of dividing and directing a neutron beam towards several experimental stations.