Abstract: A front projection composite photography system using a pair of perpendicular reflex screens combines two projected background scenes with a staged scene in a single camera shot for a versatile range of special effects. Complementary mattes are used outside the projectors and camera for either soft or hard edged merging into overall projected background scenes. A camera-projector housing cabinet includes all elements compactly except for stage reflex screens which are externally located in a small studio room. A lens permits use of a small secondary reflex screen used with a larger primary screen behind a movable stage setup. The camera, two projectors and respective associated three half mirrored transparent beam splitters provide registration adjustments for registration of all composite picture portions for immediate observation through the camera viewfinder so the film will be properly aligned and so that a complex composite picture may be produced with a single camera take.

Abstract: A family of logic circuits using nonhysteretic superconducting quantum interference devices (SQUIDs) connected together to perform various functions using a common operating principle. Each circuit has an output line, first and second power supply lines having first and second voltage states, and input lines that can have one of the two voltage states. A pull-up circuit, having at least one SQUID, is connected between the output line and the first power supply line, and the input lines are coupled to the pull-up circuit in such a manner as to pull the output line to the first voltage state only if the input lines conform with a selected combination of voltage states. A pull-down circuit, also having at least one SQUID, is connected between the output line and the second power supply line, to pull the output line to the second voltage state only when input lines do not conform with the selected combination of voltage states.

Abstract: An underwater pool light that is flush-mounted, versatile, safe, economical, easy to maintain, temperature controlled and liquid cooled, and provides the ability to direct the light in a specified direction.

Abstract: An array of semiconductor laser diodes having parallel waveguide elements, of which each adjacent pair is coupled together by an X-shaped waveguide junction having a connecting waveguide in which lateral modes are formed as a result of merging of the pair of waveguide elements. The waveguide elements diverge again from the connecting waveguide at an angle great enough to ensure that there are high scattering and radiation losses near the point of divergence of the waveguide elements, for the fundamental mode in the connecting waveguide. If an adjacent pair of waveguide elements operate in phase, this excites the fundamental mode in the connecting waveguide, which is effectively suppressed by the losses that occur near the point of divergence from the connecting waveguide. The structure thereby discriminates against connecting waveguide in an in-phase mode, resulting in operation in the 180.degree.

Abstract: A system for automatically compensating for changes in permanent magnetism in a vehicle in which a flux-gate compass is installed. Calibration is initially performed by rotating the vehicle through a full circle and determining from the flux-gate outputs the degree of distortion suffered by an ideally circular performance characteristic. Subsequent flux-gate readings are compensated in accordance with parameters generated during calibration. Parameters relating to offset or displacement of the characteristic are automatically and continually updated to compensate for changes in permanent magnetism of the vehicle, such as might be caused by loading or unloading the vehicle.

Abstract: A demodulation frequency plan for use in a global positioning system (GPS) receiver, having three demodulation stages for L1 and L2 signal channels, in which identical local oscillator frequencies are used in the L1 and L2 channels at each demodulation stage, to minimize phase error differences between the two channels. The third stage provides an output at an intermediate frequency high enough to carry the full information bandwidth, thereby simplifying digital sampling of the signal, which is also performed in the third stage. Sampling is performed at a high enough rate to facilitate subsequent conversion to baseband. Moreover, the sampling rate is a binary multiple of the intermediate frequency, and this binary relationship further simplifies conversion to baseband.

Abstract: A semiconductor diode laser device, and a related method for its fabrication, the laser being of the type from which light is emitted in a direction perpendicular to planar layers forming the device. The laser includes an active layer and cladding layers formed on a supporting substrate, and a highly reflective semiconductor stack reflector formed on one of the cladding layers. The semiconductor stack reflector may be placed in contact with a heat sink and performs the multiple functions of electrical current conduction, heat removal and light reflection. A current confinement layer is formed laterally surrounding the semiconductor stack reflector, to provide one element of a back-biased junction that confines the current to the reflector region. A dielectric stack reflector is formed in a well in the substrate, and provides for light emission from the device.

Abstract: An automated technique for the design of microwave and similar circuits using a knowledge based computer system containing a library of fixed-topology circuits and an associated store of knowledge concerning the performance and limitations of these circuits over a variety of operating conditions. The method of the invention permits a relatively unskilled user to specify a circuit by performance parameters only, and to obtain as an end product a coded output that will drive a conventional mask fabrication system used to produce the circuit. Important features of the invention include its use of a unified data structure in which both physical and electrical characteristics of every circuit element are stored together in the rationally consistent manner to facilitate circuit layout, and its use of a circuit compaction procedure that makes use of the unified data structure and minimizes the circuit area without adversely affecting electrical circuit performance.

Abstract: Apparatus, and a related method for its operation, for producing a high-power optical beam from a free-electron laser, at a high overall efficiency. Electrons are accelerated in an electron acceleration system producing bunches of electrons having a narrow energy spread but relatively long time spread. A bunch compression technique converts each bunch to one having a narrow time spread and relatively wide energy spread, suitable for injection into the gain region of a free-electron laser. After exit from the gain region, each electron bunch is further processed to restore it to the same energy-phase distribution as electrons produced by the acceleration system. The restored bunches of electrons are decelerated in the acceleration system, to conserve energy and increase the overall efficiency of the system.

Abstract: A deformation sensing device, and related method, for measuring overall deformation of a structural member subject to deformation by an actuator. The device includes a first sensor located in a region of influence of the actuator and a second sensor located outside but near to the region of influence of the actuator. The device takes a weighted average of output signals from the two sensors, using weighting factors that, in one embodiment, are applied either electronically and are selected either as proportional to the lengths of the member regions under the influence of the actuator and not under the influence of the actuator, or are selected to provide a desired transfer function between input to the actuator and output from the sensing device. In other embodiments, weighting of the output signals is obtained by using different surface areas for the sensors or by appropriately positioning two shear-mode sensors in relation to the region of influence of the actuator.

Abstract: A hydrotherapy jet assembly that produces rotating and pulsating streams of water and provides for user adjustable flow control, and user adjustable control of the speed of rotation independently of the flow control. The assembly includes a nozzle rotor supported for rotation in a generally cylindrical body, and a rotor retainer cage having a thrust plate that applies an axial retaining force to the rotor. The rotor has two internal passages that discharge water in directions that may be selected to produce a turning moment applied to the rotor. Fins may be incorporated into the rotor to produce or contribute to rotation. In all of the disclosed forms of the rotor, radial thrust components resulting from discharge of water through the two rotor passages cancel each other. The rotor is thereby balanced in directions transverse to its axis or rotation. Axial thrust components resulting from the discharge of water from the nozzle rotor are substantially balanced by the force of water entering the rotor.

Abstract: A large-area electron source which can operate continuously, stably, and indefinitely in a poor vacuum environment. The source includes a glow discharge cathode, appropriately positioned with respect to a target anode, and a fine-mesh grid spaced from the cathode by a distance less than the mean free path length of electrons leaving the cathode, the grid being electrically biased to control the electron beam current over a wide range with only small grid voltage changes. An accelerating voltage applied to the cathode can be varied continuously from as low as a few hundred volts to 30 KeV or greater and the source will continue to operate satisfactorily. Further, the grid is made of a fine mesh wire of sufficiently small dimensions as to not be resolvable in the target plane. A further refinement of the device utilizes scanning coils to achieve additional uniformity of the incident beam at the target plane.

Abstract: Apparatus and a corresponding method, for removing the effect of phase aberrations introduced into an incident light wave by a large optical element, such as a large concave mirror. Rather than building additional precision into the mirror, phase correction is effected by first collimating and phase conjugating the incident beam after reflection from the mirror, then expanding the beam again to fill the mirror. After its second reflection from the large mirror, the light beam is practically free of phase errors, since the phase conjugated beam is subject to substantially the same phase aberrating conditions as the incident beam. The apparatus may be used to produce an aberration-free image of a distant object, or to produce an aberration-free collimated light beam from a diffraction-limited laser source.

Abstract: An intrusion-alarmed optical communication system in which two separate modal groups are launched into a single graded index transmission fiber. The system includes two light sources and a lens to focus the light sources into the transmission fiber. A spatial filter is used to selectively limit the angles of incidence of the light on the fiber, and operates in conjunction with the lens to launch light from one source at appropriate angles and points of excitation to excite higher-order modes in the fiber, and to launch light from the other source at appropriate angles and points of excitation to excite lower-order modes in the fiber.

Abstract: Apparatus, and a corresponding method, for phase-modulating an optical carrier signal. An input data signal is passed through a derivative filter to obtain a time-differentiated data signal, for application directly to a laser diode, which functions inherently as a frequency modulator. The carrier signal is frequency-modulated by the time derivative of the input signal, and this is equivalent to being phase-modulated by the input signal.

Abstract: A semiconductor laser array with features providing good beam quality at high powers, first by employing a laterally unguided diffraction region in which light from a set of waveguides is re-imaged in accordance with the Talbot effect and two arrays of waveguides may be used to provide a spatial filtering effect to select a desired array mode. This provides a laser array with increased power per unit solid angle, and with additional advantages of ability to scale the device up to larger arrays, ability to control the electrical excitation of the device for better optimization, and improved modal discrimination. A second aspect of the invention is the use of a resonance condition in an antiguide array, to produce a uniform near-field intensity pattern and improved coupling and device coherence.

Abstract: A two-dimensionally scannable antenna system for transmission or receiving a microwave beam over a wide angular region, using multiple parallel plate lenses for focusing and to provide, in conjunction with a like number of phase shifters, scanning of the beam in one transverse direction, such as in azimuth. The multiple parallel plate lenses provide output signals for processing by a single diode grid lens, which provides for deflection of the beam about the other transverse axis, to scan the beam in elevation. The diode grid lens includes parallel conductive plates with a thickness tapered from a minimum value near the input and output of the diode grid lens, to a maximum value over most of the length of the diode grid lens. This increased thickness of the plates reduces the required number of switchable diodes in the diode grid lens. The device of the invention has fewer components, lower power consumption and corresponding lower cost than similar configurations available prior to the present invention.

Abstract: Method and apparatus for use in a global positioning system (GPS), to obtain the benefit of L2 carrier signals and precise-code (P-code) signals transmitted from satellites in encrypted form. Received, encrypted P-code signals are correlated with a locally generated P-code sequence and the resulting signal is bandpass filtered and squared, to separate one satellite signal from the others, to recover the carrier signal and make accurate measurement of its phase and pseudorange, even though the received P-code sequence is encrypted. Because the squaring step is performed over a narrower bandwidth than the original P-code, there is less degradation in the signal-to-noise ratio of the received signal, as compared with squaring over the entire P-code bandwidth. Therefore, performance is more reliable under weak signal conditions or when there are interference signals present, and the improvement in signal quality means that cycle ambiguity of the carrier signals can be resolved more rapidly.

Abstract: Apparatus, and a method for its use, for linearly phase-modulating a microwave signal with only minimal accompanying amplitude modulation. An incoming signal is divided into two components, one of which is shifted by ninety degrees from the other, plus or minus a small offset phase angle selected to minimize amplitude variations in an output signal. The component with the offset phase angle is amplitude modulated, then recombined with the other component to provide the desired phase-modulated output signal. When the offset phase angle and the nominal amplitude of the amplitude-modulated component are appropriately selected, phase modulation of the output signal is substantially linearly related to the amplitude modulation of the offset input signal, and amplitude modulation of the output signal is minimized.

Abstract: A multiple-redundant computer system having multiple computational devices operating in synchronism, multiple voter circuits to provide voted memory reading operations for the devices, and multiple fault detection logic for the detection of failures of the computational devices. Fault status words generated by the fault detection logic are also subject to a voted read by the multiple computational devices, thereby permitting detection of errors in the fault detection logic itself, as well as in the computational devices. The module structure of the invention also permits removal and replacement of circuit modules, each including a computational device and fault detection logic, without disconnecting power from the entire system.