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 sources. Multiple simultaneous scan lines may be employed to generate a raster scan at lower mechanical scan frequency.

Abstract: A holographic grating element is provided which enables tracing different scan lines. The element is divided into a plurality of sectors. A first grating pattern is provided which diffracts a beam in one direction, and a second grating pattern is next to the first and diffracts the scan beam in the reverse direction. Sectors can be produced with different sector sizes to enable scanning at different rates in the reverse direction, or in successive scans in the same direction. Angle relationships are described to produce diffraction patterns for a desired relationship between disc rotation and the angle of the scan line.

Abstract: An optical system for use in a scanning system for reading symbols. The scanning system includes a head for containing the optical system. The optical system comprises a light source for generating a beam of light. A scanner is provided for directing the beam of light towards the symbol and scanning the beam of light across the symbol. Further, in accordance with the present invention, a dead zone-reducing optical system is provided in the head for lengthening the optical path length between the light source and the scanner to reduce the length of the dead zone exterior of the head. A collector collects light reflected from the symbol and directs it to a detector. The collector includes at least two sectors each having different focal lengths. The detector detects the variable intensity of the returning portion of the reflected laser light over a field of view, and generates an electrical signal indicative of the detected variable light intensity.

Abstract: Combining scan fragments of a bar code symbol. Each fragment is represented by a series of values, with each value representing the width of an element in the fragment. The alignment at which the fragments are combined is determined by shifting the alignment of the fragments over a range of positions, and determining for each position an index of the overall degree of similarity between the aligned values of the two fragments at that position. The fragments are combined at an alignment that produces a relatively larger index value (e.g., that maximizes the index). The index of overall similarity may be a correlation factor representing the degree of correlation, at each tested alignment, between the series of values representing each fragment. The index of overall similarity may alternately be the number of consecutive matching elements. At each position, the values in each series are compared and the number of consecutive values that match within a preselected tolerance is determined.

Abstract: In order to improve security for holographic labels which are positioned on a substrate base, a bar code symbol with regions of different light reflective properties is holographically recorded on the base. The base may be, for example an information card, such as a credit card, a label, or a container for a product. The bar code symbol can be recorded so that it is visible to the eye in white light (e.g., as a rainbow hologram) or so that it requires an appropriate reference beam for reconstruction. 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.

Abstract: In an optical scanner, a component for producing a beam scanning motion is mounted on a first flexible strip or planar spring. One or more additional flexible strips, adjacent the first flexible strip, provide additional support to prevent droop by the first flexible strip under the weight of the scanning component. The additional flexible strips also frictionally damp the low frequency motion of the first flexible strip to prevent interference with scanning due to vibration induced from movement of the scanner by an operator. In two-dimensional scanners, where the component moves in two orthogonal directions at two different speeds, the additional strip type frictional damping is applied to the planar spring which provides the necessary flexible support for motion in the slow speed scanning direction.

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: Scanner optics, usable for example in a bar code reader, generate a multitude of Gaussian beams derived from a common light source to produce a beam with extended working range. In the preferred embodiment, a 360 degree fan of Gaussian beams is generated by passing a laser beam through at least one diffractive element, e.g., computer generated holographic (CGH) plate, computed to perform the transformation of the illuminating beam into the desired output beam. The beam thus produced, having a small diameter over a large longitudinal distance, is useful for long range scanning.

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 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: 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: 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: Optical analog data processing systems are described for handling both bipolar and complex data. Multi-cell spatial light modulators are employed in which a plurality of modulation areas are used in conjunction with space and time mutliplexed configurations to process bipolar and complex data elements. Multi-cell light detector arrays are used to convert modulated light into signals representing the processed data. The processing systems are capable of real time processing of synthetic aperture radar data.

Abstract: A high frequency spectral analysis system and method operates by modulating an optical beam with a high frequency signal to be analyzed, and sampling the beam simultaneously at periodically spaced locations along its length. The sampled portions are then focused to a spectral mapping. In the preferred embodiment a beam is directed in a zigzag pattern through a plate, one surface of which is totally reflective and the opposite surface of which is partially reflective. Periodic parallel samples are obtained from the minor portions of the beam which are transmitted out of the plate through the partially reflective surface. The totally reflective surface is preferably formed as a series of cylindrical surfaces which focus the beam to small spots at the partially reflective surface, thereby permitting a higher spatial density of samples without overlapping. The plate thickness is selected so that the beam is sampled at the Nyquist rate for the highest frequency contained in the signal of interest.

Abstract: Optical data processing systems are described for processing four NxN matrices A, B, C, D to calculate the expression CA.sup.-1 B+D. Multi-cell spatial light modulators are employed in conjunction with control circuits to perform matrix inversion, multiplication and addition.

Abstract: An improved optical rotary joint is achieved by transmitting information in the form of an optical signal from a part of the de-spun portion outside the rotational axis to create on the spun portion, or vice versa, 360.degree. about the rotational axis, a continuous communication path having a configuration described by a series of overlapping elliptical areas. The detection area on the spun portion is less than that of the detection path thereby providing continuous optical communication with the transmitted optical signal.

Abstract: Associative holography memory apparatus is disclosed which employs a hologram, two phase conjugate mirrors, and a two-wave mixing contra-directional coherent image amplifier. The mirrors and amplifier are arranged to form a conjugate resonator whereby the output image from the apparatus tends to converge to that stored image most closely associated with an input image. Alternate embodiments are described which employ a multiple storage and erasure hologram, and which employ only a single phase conjugate mirror.

Abstract: Associative holography memory apparatus is disclosed which employs a hologram and two phase conjugate mirrors. The mirrors are arranged to form a conjugate resonator whereby the output image from the apparatus tends to converge to that stored image most closely associated with an input image. Alternate embodiments are described which employ a multiple storage and erasure hologram, and which employ only a single phase conjugate mirror.

Abstract: A technique for subtracting images in real time utilizing a single liquid crystal light valve (LCLV) is described. The two images are projected on the LCLV through a common grating in a well-determined geometry. The interrogating light beam is optically filtered, so that only different features in the two images are revealed.

Abstract: Apparatus for performing a division of a dividend intensity array by a divisor intensity array on a pixel-by-pixel basis, to yield a quotient intensity array, wherein optical feedback principles are utilized in conjunction with two spatial radiation modulators, so that analog division is achieved. Specifically, a fraction of the output array of a first spatial radiation modulator is provided as the readout array to a second spatial radiation modulator, whose input is the divisor intensity array. The output array of the second image converter is then added to the dividend array and provided as the input to the first spatial radiation modulator, whereupon the output of the first spatial radiation modulator is the pixel-by-pixel quotient array resulting from division of the dividend array by the divisor array.