Abstract: There is disclosed an electro-optical system for real time projection of very high brightness, full color pictorial images from television or other program sources onto a large display screen from a set of three reflection type AC driven field effect mode birefringent liquid crystal light valves each of which modulates a primary color component video image onto a collimated beam of polarized light of a given primary color by modulating the polarization state thereof. In order to achieve very high brightness without overheating the system it is necessary that none of the optical elements forming the projection beam optical system absorb light in carrying out their function. Hence all projection beam optical processes are non-absorptive to first order. The light valves are devices that receive and reflect projection light from an independent high power light source while modulating onto the reflected light video images derived from a low level light source such as a cathode ray tube.

Abstract: There is disclosed a system capable of subtracting in real time the intensities of two incoherently illuminated scenes and providing the sign of the subtracted information. The system utilizes two birefringent devices such as liquid crystal light valves, onto which the two images to be subtracted are projected. One valve is analyzed in between crossed polarizers, or equivalent, while the other one is in between parallel polarizers or equivalent. Both polarizer arrangements, for example, may be implemented with a polarizing beam splitter and a quarter wave plate. The common output image plane, onto which both images are superposed, displays an intensity proportional to the difference between the two inputs. This intensity "rides" on a constant background intensity thus displaying the difference signal as well as its polarity. The read-in and read-out beams could be coherent as well as incoherent, the latter being more desirable due to its speckle-free image.

Abstract: There is disclosed a liquid crystal display device which utilizes an elliptical mirror to present a magnified image of a light trap across the surface of a liquid crystal display element which is positioned with respect to the mirror and the light trap so as to simultaneously receive both ambient and auxiliary illumination on the surface of the display element from the mirror at angles where liquid crystal scattering is most effective. The auxiliary light source may be positioned adjacent to the light trap. The display element is positioned such that the viewing angle for the observer is below the horizontal line from the observer to the plane of the display element.

Abstract: There is disclosed an optical fiber connector for use in glass fiber waveguide transmission systems to provide either a permanent splice or a fiber guide connection which can be disengaged. The connector comprises a sheet of elastically deformable material such as a plastic having opposed major plane surfaces. At least one hole is formed in the material which hole has the same shape and dimension as the fiber portions which are to be inserted into opposite ends of the hole and aligned and joined therein. The hole extending through the sheet of material is parallel to one of its major plane surfaces and is positioned to be nearer to this one surface than to the other surface of the material so that when the material is bent along the axial direction of the hole the hole deforms or elongates to permit removal or insertion of fiber ends to be aligned and held securely therein when the deformation is released and the material goes back to its original shape.

Abstract: There is disclosed a reflective type liquid crystal light valve means for converting a visible wavelength dynamic image to an infrared wavelength dynamic image. The device employs an infrared reflecting and visible transmitting indium-tin-oxide film which is external to the liquid crystal layer and active films and which also serves as a conductive electrode for the device. In operation, a visible image is transmitted through a visible transmitting faceplate and through this ITO film to a photosensor to modify its impedance. An infrared projection beam is transmitted through a second infrared transmissive faceplate, through the liquid crystal means and the photosensor to the IR reflective dichroic film and thence back through the rest of the liquid crystal cell for projection.

Abstract: There is disclosed an anisotropically conductive interface comprising a plurality of cermet and dielectric layers for use in electro-optical devices to separate a substrate driver from an electro-optical display medium to prevent display light from affecting the driver. The substrate may be a photosensor, a charge coupled device or other matrix addressing circuitry arrangement. In general the substrate is one which can provide spatially modulated voltage and/or current patterns. The display medium may be a liquid crystal, an electro-chromic, an electro-luminescent material or the like. The interface provides direct current conductivity through the interface, insulative maintenance of the spatial modulation of the signal across the interface, light reflectivity, and high attenuation of transmitted light.

Abstract: There is disclosed a quadrant detector which is characterized by an optical reflector immersed in a high refractive index material to increase the field of view of the detector. The immersed reflector divides the incoming radiation and directs varying portions of this radiation to four separate immersed detectors. The device thereby achieves an increased field of view for proportional operation of a quadrant detector. The high index material reduces the spread of the incoming rays and the ray bundles can then be collected by a much smaller detector than would be required by a conventional quadrant detector with the same field of view. Sensitivity is increased and the need for gimbals is often eliminated.

Abstract: There is disclosed a circularly polarized light source including a circular light polarizer using cholesteric liquid crystal material in an arrangement such that substantially 100% of the unpolarized light input may be utilized in a circularly polarized output in either a narrow band or wide band configuration. The circular polarizer itself comprises one or a plurality of liquid crystal cells having liquid crystal material of a predetermined ratio by weight of cholesteric to nematic liquid crystal type in each cell. The ratio of the types of materials determines a central wavelength to which each cell is tuned in its polarizing action. If a single cell is used, light of a predetermined bandwidth around its central wavelength is polarized.

Abstract: There is disclosed a fiber optic coupler for use in single strand fiber systems comprising a device to allow optical access to a single fiber by means of a second fiber which has been attached to it by fusing the glass cladding of the two fibers as by application of heat by a laser. The resulting access coupler provides for coupling both into and out of a single strand of fiber optic waveguide. That is to say, an input optical signal to one single fiber strand can be read out at more than one point on the single fiber or more than one input can be read out at a single point. The coupler is sufficiently low loss to make control systems utilizing single fiber lines rather than bundles a realistic possibility.

Abstract: There is disclosed a silver doped silicon single crystal charge storage photodiode substrate suitable for use in an alternating current driven liquid crystal light valve. The gain capability of the charge storage photodiode makes it possible to construct a single crystal substrate ac light valve very similar in structure to that presently being used with a cadmium sulphide photodiode, but having improved operating characteristics and benefitting from a more fully developed manufacturing technology for silicon devices. One specific embodiment of such a single crystal substrate is a silicon substrate doped with a slow recombination center element such as silver.

Abstract: There is disclosed a high performance reflective mode liquid crystal light valve suitable for general image processing and projection and particularly suited for application to real-time coherent optical data processing. A preferred example of the device uses a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state.

Abstract: There is disclosed a high performance coherent optical data processing system using a reflective mode liquid crystal light valve which is particularly suited for application to real-time coherent optical data processing. A preferred example of the system uses a reflective light valve comprising a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state.

Abstract: There is disclosed a pulse processing method and apparatus for compressing or changing the time scale of signal information represented by the modulation of a pulse of carrier energy which method and apparatus utilizes a crystal through which both a pulse of radio frequency acoustic energy and a pulse of polarized optical energy are simultaneously and colinearly transmitted to scatter energy in the optical pulse from one polarization state into the orthogonal polarization state. The crystal output is thus comprised of two optical pulses. One is the pulse having the original state of polarization and the other is the pulse resulting from the energy scattered to the orthogonal polarization state. The optical energy of rotated polarization is modulated in a fashion reproducing the modulation of the ultrasonic wave by which it is scattered. Furthermore, a short optical pulse can pass through the ultrasonic wave in a time short compared to the duration or length of the ultrasonic wave in the crystalline device.

Abstract: There is disclosed a bias circuit for a photo-avalanche diode in equipment such as a laser receiver which circuit utilizes the breakdown characteristics of the actual detector diode itself to regulate the applied detector diode bias voltage. This is achieved by providing means to charge a capacitor up to the breakdown voltage in response to a first timing pulse, and second means to offset the capacitor voltage to a lower level by the fixed amount of a positive reference voltage, responsively to a second timing pulse which renders a transistor conductive.

Abstract: There is disclosed a synchronous traveling wave electro-optic modulator for ultra-wideband infrared laser communications systems which provides optical waveguiding of the laser beam through an interaction distance which is large relative to the diffraction limit of the laser beam and which affords essentially perfect radio frequency and optical velocity synchronism at a relatively high electrical impedance level by appropriate choice of the design parameters of the device. The device comprises an array of very slender rectangular rods of electro-optic material such as cadmium telluride laid end to end in juxtaposition to form a light pipe for an infrared laser beam. The length to cross-section ratio of the light pipe is many times greater than that which is determined by the diffraction limit and consequently the voltage and power required to achieve a given depth of modulation is substantially reduced.

Abstract: There is disclosed a method and apparatus for radio frequency signal spectrum analysis wherein an acoustic wave having frequency components representative of those which exist in the radio frequency signal to be analyzed is derived from the signal and transmitted through an optically anisotropic crystal simultaneously and colinearly with a beam of polarized wide-band white light. The acoustic wave produces changes in the index of refraction of the crystalline material which result in diffraction of the plane of polarization of those frequency components of the light beam which bear a unique predetermined relationship to the frequency components present in the acoustic wave. The output of the crystal is then passed through a polarization analyzer to transmit only those frequency components which have been polarization diffracted.

Abstract: In a light actuated device such as an alternating current driven light valve or other display device requiring the photocapacitance of a light responsive layer in a photodiode to be modulated in response to changes in incident or writing light, sensitivity is an important factor, especially when a cathode ray tube phosphor image is the source of such light. This sensitivity can be improved by more than an order of magnitude by using a graded defect center (as defined hereinbelow) concentration, graded band gap layer in said diode which can produce a graded optical absorption coefficient between two regions of the layer so that most of the incident light is absorbed in the region near the semiconductor rectifying junction of the diode to store charge near this junction by this or any similar action.

Abstract: There is disclosed coercivity control and signal generating and detection means comprising a two-dimensional lattice array of dots of magnetically susceptible material in intimate physical contact with the major plane surface of a uniaxially anisotropic ferromagnetic crystal platelet which has its major plane surface cut perpendicularly to the easy axis of magnetization of the crystal so as to be capable of sustaining movable cylindrical magnetic domains therein. Such crystals are used in digital signal translating and memory devices. In the conductor access type of device disclosed herein such domains are moved between predetermined locations in the crystal by electrical drive signals in magnetic field generating conductor loops.

Abstract: There is disclosed a circuit for removing the DC or background representing charge component of a signal to be passed through a charge coupled device shift register without degrading the information carried by the AC component of the signal. Such a circuit may, for example, be used to remove the constant background illumination component of the input from a semiconductor imaging device to increase the contrast ratio of the image signal. The circuit comprises two electrode defined potential wells or buckets formed in a semiconductor substrate with a control gate between them and a transfer gate which controls the flow of the charges in the first bucket to a P-N junction. Like the well defining electrodes, the control gate and transfer gate are electrodes separated from the semiconductor substrate by an insulation layer.

Abstract: An electrical field sustained conductivity device is fabricated by successively disposing over a layer of cadmium sulfide a film of metal particles and a composite layer of metal particles in an insulating medium. When a potential is applied across the cadmium sulfide layer, an image may be stored therein by momentarily exposing the layer to electrons or light conveying that image. Such exposure introduces conductivity changes in the cadmium sulfide layer by virtue of the layers deposited on it and the conductivity changes are retained so long as the applied potential is maintained.