Abstract: The invention facilitates operation of a bar code reader over a wider range of working angle, a wider range of distances from the bar code and a wider range of bar code densities. The invention includes improved optics and sensing elements. To provide a wider depth of field the optics associated with the emitter and or the photodetector have two distinct focal points. In the preferred embodiments, the optics and sensing elements and/or the associated circuitry are arranged to provide two channels of data derived form the scanned bar code. The two channels have differing resolutions. Analysis of the data from the two channels provides a single decoded result. As the working angle and density vary at least one of the resolutions will be appropriate for sensing all or most of the bar coded data.

Abstract: The use of linear axicons or similar optical elements in a bar code scanner produces a scanning spot of a size correlated generally with dimensions of features of the scanned information, wherein the spot size remains substantially constant for varying distances between the scanner and the symbol over a substantial range of distances. Optical elements of this type produce a diffraction pattern comprising a central lobe and a number of rings surrounding the central lobe. An aperture is provided to limit the beam and thus the number of rings in the pattern which actually reach the symbol during scanning. The extent of the limited beam and the phase front tilt angle produced by the optical element are chosen to produce a desired resolution, which relates to the density of symbols the scanner is to read, and to produce a desired working range.

Abstract: In order to improve security for holographic labels which are positioned on a substrate base, a bar code symbol is holographically recorded on the base such as a credit card, a label, or a container for a product. A reading apparatus (e.g., a bar code reader) directs light at the holographic bar code symbol and detects the reflected optical information with a detector such as a CCD array. The reading apparatus can be a stand-alone device or, in the case of a credit card, can be incorporated into a conventional swiper for reading magnetic information on a strip on the card. A non-holographic bar code symbol can also be provided on or near a holographic display element, e.g., a rainbow hologram. The bar code can be positioned adjacent the display, or placed in a window within the display, or etched or embossed on the display. A system is also provided for authenticating a holographic display on an information card such as a credit card.

Abstract: A laser scanning head in which the range of the beam waist is varied independently of any measurement of the actual range of the symbol. The optical member is a condenser lens that is moved by energizing a magnetic coil; the lens is operated independently of the scanning movement of the laser beam, to produce a continuous, progressive variation (e.g., a continuous oscillation) in the range of the beam waist, so that at some point in the variation the spot size on the symbol will be of an appropriate size. The movement of the lens can be synchronized with the beam scan (e.g., so that the same spot size can be maintained for several scans). Spot size can be chosen adaptively, by varying the range of the beam waist until the contrast in the reflected light collected from the symbol exceeds a predetermined level.

Abstract: A scan pattern generator for use in a bar code reader which uses a single drive (one coil and one magnet) to produce movement of a reflective surface so as to produce an oscillating movement of the surface in two directions, thereby forming a raster-type scanning pattern when a light beam is reflected off the surface.

Abstract: The method and apparatus of this invention facilitate operation of a bar code reader over a wider range of working angle and for a wider range of bar code densities. The invention includes improved optics and sensing elements. The optics and sensing elements and/or the associated circuitry are arranged to provide two channels of data derived form the scanned bar code. The two channels have differing resolutions. Analysis of the data from the two channels provides a single decoded result. As the working angle and density vary at least one of the resolutions will be appropriate for sensing all or most of the bar coded data. The data from the channel producing a valid result can be used, or if neither channel produces a valid result by itself, data from each channel can be analyzed and valid portions of the data from both channels combined to produce the single decoded result.

Abstract: A bar code scanner employs an electronic means for causing the light beam to scan a bar code symbol, rather than using a mechanical device to generate the scan. A linear array of light sources, activated one at a time in a regular sequence, may be imaged upon the bar code symbol to simulate a scanned beam. Instead of a single linear array of light sources, a multiple-line array may be employed, producing multiple scan lines. The multiple scan lines may be activated in sequence, or activated simultaneously (time-division or frequency-division multiplexed. The multiple scan lines can provide signal enhancement, noise reduction or fault correction if directed to the same bar code pattern. Multiple scan lines may be generated using a single light source and a beam splitter, with mechanical scanning, as well as by the sequentially-activated light suorces. Multiple simultaneous scan lines may be employed to generate a raster scan at lower mechanical scan frequency.

Abstract: Microscopic, neutrally buoyant particles containing fluorescing compounds used for tracers of large scale turbulent flows. The particles are generated by dissolving acrylics in a solvent and mixing the solution with fluorescing dyes. This mixture is sprayed into a heated chamber where the solvent evaporates, and the solid acrylic with the imbedded dye settles on the bottom of the chamber. The dust is collected, and the particles are separated according to size using a filter. Dye residue on the particles' surface is washed leaving the dye imbedded within the particles. The particles are then used within flow fields.

Abstract: A bar code detector or acquisition arrangement for detecting the presence and location of a bar code pattern in a field of view. The bar code pattern detector is not designed to decode a bar code pattern, but merely to be sensitive to and detect the presence of a bar code pattern or patterns so that a conventional bar code scanner can then be activated to perform a decoding operation thereon. The present invention is based upon the generation of Moire patterns, and includes an electro-optic system for detecting and locating a bar code pattern in which an image of a field of view is projected onto a reference bar code pattern or an image thereof while producing relative rotation between the image of the field of view and the reference bar code pattern or image thereof. An optical detector detects the optical interaction of the image of the field of view with the reference bar code pattern or image thereof, including any Moire patterns generated thereby.

Abstract: Several embodiments are disclosed of bar code readers in which one or more piezoelectric bimorph elements are utilized as a drive element in the optical system thereof. In different embodiments, the piezoelectric bimorph element is utilized in the scanning function of the bar code reader optical system, or in a variable focus zooming function of the optical system. The bar code readers are provided with improved decoding reliability, speed and orientation freedom, with regular or high density, one or two dimensional bar codes, by using multiple beam symbol crossings, created by using one or more piezoelectric bimorph elements. In different disclosed embodiments, one or more cantilever mounted piezoelectric bimorph elements support a scanning mirror, or a focusing lens, or a laser diode, or a laser diode and limiting aperture, for movement at the free ends of the bimorph elements to produce a scanning of the bar code reader optical system.

Abstract: High speed scanning arrangements in scanners for reading bar code symbols by oscillating a scanner component mounted on an arm of an asymmetrical U-shaped spring in single or multi-axis scan patterns.

Abstract: Two-dimensional information such as a written signature can be captured and subsequently reconstructed by using an electro-optical scanner. A multi-row preamble code and a multi-row postamble code flank the signature, and each code has a row identifier for identifying which row is being scanned by a scan line emitted by the scanner, as well as start/stop data for identifying when each scan line traverses the boundaries of a space containing the signature.

Abstract: Microscopic, neutrally buoyant particles containing fluorescing compounds used for tracers of large scale turbulent flows. The particles are generated by dissolving acrylics in a solvent and mixing the solution with fluorescing dyes. This mixture is sprayed into a heated chamber where the solvent evaporates, and the solid acrylic with the imbedded dye settles on the bottom of the chamber. The dust is collected, and the particles are separated according to size using a filter. Dye residue on the particles' surface is washed leaving the dye imbedded within the particles. The particles are then used within flow fields.

Abstract: A bar code scanner is disclosed employing a laser source and scan mirror for generating a light beam for scanning a bar code symbol or the like. The working range for distance between the scanner and the symbol is extended by placing an optical element in the path between the laser source and the scan mirror. This optical element may be a figure of rotation such as an axicon. A slit may be positioned downstream of the axicon to block the characteristic concentric rings produced in the beam in areas perpendicular to the scan line.

Abstract: Tunable far infrared radiation is produced from two-dimensional plasmons in a heterostructure, which provides large inversion-layer electron densities at the heterointerface, without the need for a metallic grating to couple out the radiation. Instead, a light interference pattern is produced on the planar surface of the heterostructure using two coherent laser beams of a wavelength selected to be strongly absorbed by the heterostructure in order to penetrate through the inversion layer. The wavelength of the far infrared radiation coupled out can then be readily tuned by varying the angle between the coherent beams, or varying the wavelength of the two interfering coherent beams, thus varying the periodicity of the photoconductivity grating to vary the wavelength of the far infrared radiation being coupled out.

Abstract: A PIN GaAlAs diode structure is provided with parameters for index guiding of light in a single mode. The index of refraction of the central layer I (which in practice may be lightly doped .pi. or .nu.) is greater than the p- and n-layers to create a slab waveguide in the transverse direction. Stripe contacts define separate waveguide channels that are separated electrically and optically by implanting protons or etching grooves between the stripe contacts in the upper layer. Separate reverse biasing voltages may be applied to the stripe contacts for modulation of the light in proportions to the voltage, either with absorption modulation, if the light wavelength is within about 500.ANG. of the bandgap of the .pi.-material, or phase-delay modulation, if the wavelength is separated from the bandgap of the .pi.-material by at least 900.ANG..

Abstract: An array of nonuniform semiconductor diode lasers with supermode control for achieving a single-lobed farfield pattern is described. This is accomplished by spatially segregating the fundamental supermode from the other supermodes, tailoring the spatial gain profile as as to favor the fundamental supermode, and sufficiently increasing the intechannel coupling so as to bring about single-lobed farfield operation. In a preferred embodiment, this is achieved in a shallowly proton implanted, tailored gain, chirped laser array in which the widths of the lasers are varied linearly across the array.

Abstract: There is disclosed a marine calculator of the slide rule type whereby the running distance to a destination station over a dogleg or zig zag course may be readily determined from knowledge of the rhumb line course distance and the departure angle of the dogleg or zig zag course.

Abstract: An integrated laser structure for paired stripe semiconductor lasers is provided with separate current control of each stripe laser. With optical coupling between the lasers, one of the lasers is operated below threshold and serves the longitudinal mode selection and tunability of the other laser, thereby to obtain a single longitudinal mode operation. Without coupling, the paired-laser structure operates as a source of two independent wavelengths.

Abstract: An arrangement for damping the resonance in a laser diode includes an additional layer (25) which together with the conventional laser diode form a structure (35) of a bipolar transistor. Therein, the additional layer serves as the collector, the cladding layer (12) next to it as the base, and the active region (11) and the other cladding layer (13) as the emitter. A capacitor (30) is connected across the base and the collector. It is chosen so that at any frequency above a certain selected frequency (f.sub.c) which is far below the resonance frequency (f.sub.res) the capacitor impedance is very low, effectively shorting the base to the collector.