Showing papers on "Lens (optics) published in 1977"

Apparatus for forming optical lenses

Abstract: Apparatus for and method of forming ophthalmic lenses and/or semi-finished lens blanks including those of the eye contact type. The apparatus includes molds having cooperating first and second members each of which includes a longitudinal axis and a mold surface which is symmetrical with respect to such axis. In one embodiment these mold members or halves also include cooperating surfaces which, in operation and in cooperation with the selected lens material, both align the respective mold axes and axially position the mold surface of the first member with respect to the mold surface of the second member to thereby form the desired lens mold cavity. Further, each of the assembled molds also includes an annular reservoir which surrounds the mold cavity and is defined by surfaces provided on the first and second mold members. This reservoir is connected to the mold cavity via an annular restriction. In one embodiment this restriction is defined by the cooperating aligning surfaces provided on the first and second mold members. In operation, the reservoir holds a volume of lens material which, during the polymer forming reaction, is kept in a flowable state longer than the lens material in the mold cavity. This arrangement permits the transfer of lens material between the reservoir and the mold cavity during curing. Apparatus is also provided for removing selected portions of the cast lens in those instances where removal is either necessary or expedient.

Method for forming optical lenses

Abstract: Apparatus for and method of forming ophthalmic lenses and/or semi-finished lens blanks including those of the eye contact type. The apparatus includes molds having cooperating first and second members each of which includes a longitudinal axis and a mold surface which is symmetrical with respect to such axis. In one embodiment these mold members or halves also include cooperating surfaces which, in operation and in cooperation with the selected lens material, both align the respective mold axes and axially position the mold surface of the first member with respect to the mold surface of the second member to thereby form the desired lens mold cavity. Further, each of the assembled molds also includes an annular reservoir which surrounds the mold cavity and is defined by surfaces provided on the first and second mold members. This reservoir is connected to the mold cavity via an annular restriction. In one embodiment this restriction is defined by the cooperating aligning surfaces provided on the first and second mold members. In operation, the reservoir holds a volume of lens material which, during the polymer forming reaction, is kept in a flowable state longer than the lens material in the mold cavity. This arrangement permits the transfer of lens material between the reservoir and the mold cavity during curing. Apparatus is also provided for removing selected portions of the cast lens in those instances where removal is either necessary or expedient.

Variable focus liquid crystal lens system

Abstract: An optical lens system is disclosed which comprises a body of a nematic liquid crystal material placed in a variable electric or magnetic field. In response to variation of the field strength from zero to an upper limit, the focal length of the lens system changes continuously from a first focal length to a second focal length. The new lens system may be used, e.g., in cameras, telescopes, binoculars, projectors, and eyeglasses.

Knife-edge scanning measurements of subwavelength focused light beams.

Abstract: This note describes a convenient working technique for measuring the minimum size focused spot formed by a lens system. The technique is routinely capable of measurement precision of better than ?lambda. The theory of knife-edge scanning is presented, and the relationship of the measured spot profile to the actual spot profile is shown to be relatively insensitive to the acceptance solid angle of the photodetector. Finally, some typical results of high resolution microscope objectives are presented.

Describing holographic optical elements as lenses

Abstract: Optical systems including holographic optical elements and Fresnel gratings can be designed with ordinary lens optimization computer codes. Holographic elements are represented as lenses with very large indices of refraction and very small curvatures. As the index approaches infinity, the model becomes exact. General design parameters and image quality of holograms on both planar and spherical surfaces are discussed.

Method for molding optical plastic lenses of the standard and bifocal type

Abstract: A bifocal lens is produced on either a previously formed blank lens, or completely in a singular casting between two molds. The bifocular lens is obtained by supporting a bifocal lower mold having a recessed bifocal well area on itsconcave surface and filling the lower mold with a resin material. By positioning an upper mold in vertically spaced relationship to the lower mold, the resin material is displaced to extend between the overlapping surfaces of the molds to form the configuration of the bifocal lens with a bifocular portion on the convex lens surface corresponding to the bifocal well on the lower mold. Curing of the resin material situated between the molds and cooling the resin material and the molds forms the complete lens. Thereafter a separating of the bifocal lens from between the molds leaves the bifocal lens in a position to be completed and installed in a pair of eye glasses. Single vision ophthalmic lenses are similarly produced by means of the aforedescribed method.

Optical lens for differential correction

Abstract: An optical lens for differential correction comprising two transparent walls defining an enclosed space having therein a quantity of a transparent liquid with a predetermined optical index; the walls are so formed as to provide at the optical center a capillary space into which the liquid is aspirated when the lens is tilted at a predetermined angle for changing the power of the lens.

Chirped gratings in integrated optics

Abstract: Gratings with variable periods (chirped gratings) have been fabricated by recording the interference pattern of a collimated laser beam with a converging beam generated by a cylindrical lens. An analysis is presented for the behavior of the chirped gratings as a function of wavelength, the angle between the illuminating beams, the F number of the lens, and its position. To calculate the power radiated into air, the coupled-mode equations are solved for the case of a waveguide with chirped surface corrugation. Experimentally, chirped gratings have been etched on the surface of an optical waveguide and used to couple light out of the waveguide. It was found that the light was focused outside the waveguide, and the fraction of the power radiated into air compared favorably with the theoretical calculation. The focal point outside the waveguide was found to move by about 1 cm when the wavelength was changed by 500 A-in agreement with theoretical estimates.

Erasable thermo-optic storage display of a transmitted color image

Abstract: The invention provides an optical display device, utilizing a thermo-optical effect to inscribe a transmitted image in a layer of a material exhibiting a smectic state. Recording of the image with a full range of half tones without modulation of the recording beam and quick erasure of the recorded image without reheating of the film can be obtained by directly applying, simultaneously to the whole of the film either the video signal or an erasure voltage of suitable values. By associating this display device to a projection device utilizing a very bright source, the image thus recorded can be projected onto a large screen or a photosensitive substrate. The invention also describes a color images teleprojection and telereproduction device, in which three distinct chrominance images are recorded in a smectic layer as above described and simultaneously illuminated with white light; the three beams thus obtained are filtered for respectively selecting in each of them the spectral band corresponding to the chrominance of the image and superimposed in a single beam by a reflecting system. An objective lens supplied with a diaphragm in its image focal plane receives this single beam and projects the reconstituted colour image onto a screen or a photo-sensitive layer.

Method and apparatus for recognizing code information

Abstract: A light source, a converging lens and a light responsive image sensor are optically coupled to recognize the code information such as bar codes recorded on an object. The light source supplies the code information with illumination light and the image sensor receives the reflected light through the converging lens to convert it into the image signal. The distance between the lens and the image sensor is adjusted automatically in response to the image signal such that clear reflected light is received by the image sensor, whereby correct information recognizing operation is attained.

Device for scanning an object with a light beam

Abstract: Disclosed in this specification is a scanning device which scans an object having a flat reflection surface and an inclined reflection surface with an inclination relative to the flat reflection surface such as, for example, a mask and a wafer to be used in manufacturing IC, LSI, etc., with light beam, and detects only the reflected light from the inclined reflection surface with a light detector. In order to make it possible to detect only the reflected light from the inclined reflection surface with the light detector, a telecentric lens is used as the scanning lens in this scanning device, and the original point of deflection of the above-mentioned light beam coincides with the center of the pupil of this telecentric lens. In addition, a filter is disposed on the pupil surface to intercept light from the flat reflection surface.

Synchronizing signal generator

Abstract: In a device wherein a scanning beam from a light source is deflected by a light deflector, especially a rotatable polygonal mirror or a vibratory mirror and focused by an optical element such as a lens or the like to optically scan a surface to be scanned, thereby effecting writing and display of information, a synchronizing signal generator includes an optical system for taking out part of the scanning beam as a synchronizing beam for providing synchronism of signals in scanning In this device, a diffraction element such as a diffraction grating or the like serving as a beam splitter for splitting the deflected beam to obtain the synchronizing beam is disposed within the deviation range of the deflected beam, and the diffracted beam exiting from the diffraction element is directed to a photodetector so as to provide a synchronizing signal In this device, the use of the diffraction element as the beam splitter permits a wide area of the scanning beam to be split by a relatively thin member

An integrated-optical approach to the Fourier transform

Abstract: A wide-band real-time spectrum analyzer is examined as a viable integrated optical circuit for processing electronic signals. The spectrum analyzer includes a Luneburg beam expansion lens system, a surface elastooptic Bragg spatial modulator, reflectors, a Luneburg Fourier-transform lens, and a waveguide coupled photodetector array, all formed on thermally grown SiO 2 on Si as the substrate. A distributed-feedback (GaAl)As laser with hybrid coupling is included as the carrier for the optical Fourier transform. The developmental status of this integrated-optical spectrum analyzer and its essential design considerations are delineated.

Optical fiber connector utilizing opposed lenses

Abstract: This invention provides an arrangement for optical coupling, including interconnecting optical fibers, coupling a source to the fiber and coupling a fiber to a detector. The connector may comprise an objective lens and an immersion lens provided by opposed cavities in a transparent medium, each containing an index of refraction material, with the optical fibers to be connected inserted into the opposed cavities. Cavities also are used in source-to-fiber and fiber-to-detector coupling, being defined by surfaces of revolution and providing an aligning and positioning means. By appropriate selection of the indices of refraction of the index of refraction material and the transparent medium, the light from the emitting device is refracted and transmitted to the receiving device, resulting in low-loss light transmission. Means may be provided for changing the emittance angle so as to cause the light to be within the acceptance angle of the receiving device. In one embodiment at least one intermediate lens is positioned between the objective and immersion lenses.

Near uv light and cataracts

Abstract: . Sunlight and many types of artificial lighting contain near-UV light (300–400 nm). These wavelengths can enter the eye and are maximally absorbed in the lens due to its chemical composition. The lenses of certain animals develop cataracts from exposure to this light, and changes similar to those that occur in human lenses with certain types of cataracts and with aging are inducible in isolated human lenses. These changes seem to be associated with chemical alterations in the essential amino acid tryptophan either as a part of proteins or in free form. Such changes in tryptophan would result in lens cell toxicity, in increased pigmentation of the lens, and in large aggregates of proteins. The latter two changes would result in losses in the ability of the lens to transmit visible light needed for vision, and the abnormal state called cataract would result. Much more work is needed to prove that near-UV light can accelerate cataractous changes in the lenses of living humans. Studies at the basic chemical level are needed, but population studies would be most essential for the final proof. Many preventive measures could become available, including the use of special types of spectacles and dietary additives.

Eyeglass frames with removable, interchangeable lenses, rims and temple pieces

Abstract: Eyeglass frames are disclosed in which the right and left lens rims are split to facilitate insertion and removal of lenses. A pair of flanges on each rim adjacent the split mate to form a composite lug which is received between upper and lower arms on the associated temple pieces whereby the rims are held in the closed position. Pivot pin means are provided to secure the temple pieces to the lugs on the lens rims. The lug and pivot pin arrangement is generally useful for securing removable temple pieces to lens rims.

Comparison of optical-waveguide lens technologies

Abstract: Various materials, lens structures, and processes are examined relative to the lens requirements of an RF spectrum-analyzer implemented through the use of an integrated-optics format. Factors which distinguish optical-waveguide lenses and reflectors from conventional imaging lens systems are enumerated. It is concluded that a thin-film Luneburg lens is the most viable planar approach based upon the use of oxides and, when high refractive-index materials must be employed, the spherical depressed geodesic becomes a feasible alternate.

Lens-mirror combinations with maximal concentration

Abstract: By the addition of suitable reflectors the concentration of a lens can be increased to the thermodynamic limit, which is equivalent to an f-number of one half. Such lens-mirror combinations are useful whenever concentration rather than image formation is important, for example, in radiation detectors and solar energy collectors. The design of lens-mirror combinations with maximal concentration is described. To the approximation that the lens has sharp focal points at off-axis incidence, the solution for the reflector is readily found to be compound hyperbolic. With proper choice of the f-number of the lens the hyperbolic reflector reduces to a V-trough or cone, an arrangement which offers considerable advantages for fabrication. The 2-D case (line focus lens) suffers from aberrations due to focal length variation with nonplanar incidence. The optical performance of 2-D lens-mirror combinations at nonplanar incidence is analyzed and evaluated for its suitability in solar energy applications. A prototype Fresn l lens plus V-trough has been built, and test data are presented.

Single-mode wavelength division optical multiplexer

Abstract: A wavelength division optical multiplexer for combining single mode beams involves a lens formed in a thin-film waveguide and a reflection diffraction grating outside the waveguide.

Holographic memory with fringe stabilizing compensation for recording medium motion

Abstract: The holographic recording system comprises a pair of aligned first and second Fourier transforming lenses, a holographic beam splitter having a series of random phase illumination holograms at a front focal plane of the first lens and arranged to move in a given direction to successively receive a light beam for deffracting it into a zero-order diffracted beam and a first-order diffracted array of sampled, phase shifted beams, and a mask having a first and second apertures disposed at the Fourier transform plane of the first lens. A page composer having electrooptical transducers is positioned in the second aperture to receive the first-order diffracted array of beams to spatially optically modulate the incident beams in accordance with one of successive groups of binary signals. The zero-order diffracted beam is allowed to pass through the first aperture and the first-order diffracted array of spatially modulated beams are focused by the second lens to produce interference fringes between the wavefronts of zero- and first-order beams on a Fourier transform plane of the second lens on which a recording medium is positioned. The holographic beam splitter and the recording medium are conjugate to each other relative to the lens system and moved in opposite directions at equal speeds in synchronism with the occurrence of each group of binary signals, a series of two-dimensional holograms of the binary information is recorded.

Metrical Fundamentals of Underwater Lens System

Abstract: Presentation of the metrical fundamentals of underwater lens system that are associated with the recording phase and are applicable for an object space of water and an image space of air. The metrical fundamentals are presented for cardinal points; dome window ; air lens; lens system as combination of dome window and air lens; water refractive index as a function of wavelength, temperature, salinity, and pressure; water depth and pressure relationship ; and water refractive indexes versus lens system parameters, nodal image distances, and back focal distances in the form of tables for the C201 ELCAN lens.

Eyeglass lens with indicia and method of making same

Abstract: Eyeglass lenses ordinarily of the plastic, or hard resin, type which are tinted by means of a deep penetrating dye which becomes part of the molecular structure of the lens, are masked prior to being dipped into the dye solution to produce along a margin displaced from the optical center of the lens indicia such as the name of the wearer, or some other figure or symbol.

Electromagnetic field near the focus of wide-angular lens and mirror systems

Abstract: The time-averaged electric energy density near the focus of a parabolic mirror of wide-angular aperture is calculated and compared with that of an aplanatic lens system. The distributions exhibit great differences, the mirror showing a greater departure from circular symmetry, a more complicated structure and increased sidelobes. The vectorial integral representation of Wolf is derived from the Stratton-Chu formula.

Geodesic lenses in single‐mode LiNbO3 waveguides

Abstract: A waveguide geodesic lens formed in a single‐mode Ti‐diffused LiNbO3 waveguide is reported. The paraxial focal length of the geodesic lens fabricated was 1.1 cm. In addition, a novel technique for ultrasonic impact grinding of profiles of arbitrary shape was developed. The paper describes the first single‐mode geodesic lens fabricated in a LiNbO3 substrate.

Modular rod lens assembly and method of making the same

Abstract: A rod lens assembly having a flexible outer tube and a plurality of lens modules disposed in end-to-end relation therein. Each module comprises a rod lens secured within a protective cylindrical sleeve which extends axially beyond the end faces of the lens and which is provided near its ends with a pair of outwardly-projecting annular ribs. The ribs engage the inner surface of the flexible tube to support the modules in axial alignment with each other and to permit limited flexure of the outer tube without the transmission of bending or flexing forces to the modules themselves. The axial-projecting end portions of the sleeves serve as integral spacers which provide precise spacing between the opposing end faces of successive lenses when the tube is in its normal unflexed condition and which provide pivot points for the articulation of adjacent modules when the outer tube is flexed.

Rod lens assembly and method of making the same

Abstract: A rod lens assembly for endoscopes and the like which includes an inner tube or barrel disposed in spaced or floating relation within a protective outer tube, the outer tube preferably including an inner layer of light-transmitting fibers and the inner tube containing a plurality of axially-spaced image-transmitting rod lenses. The wall portions of the barrel extending between the ends of adjacent lenses are provided with openings to allow precise positioning of the lenses during assembly and to provide zones of preferential flexure of the barrel when the entire assembly is flexed in normal use. In one embodiment, the cylindrical lenses are fixed in place by clamping forces exerted by the normally non-cylindrical walls of the barrel. The method for making such an assembly, including the steps of inserting, adjusting, securing, and cleaning the lenses, is also disclosed.

Inhomogeneous optical waveguide lens analysis

Abstract: Gradient-index ray-tracing techniques are used to evaluate performance of inhomogeneous optical waveguide lenses. Using the thin-film waveguide parameters including the lens thickness profile, the phase error and diffraction pattern are derived. The procedure is applied to a classical Luneburg index profile for which exact results are known. The results indicate that better than diffraction-limited accuracy can be achieved with reasonable computer running times. A second example demonstrates the procedure on lens profiles approximating generalized Luneburg lenses (image surface is outside the lens).