Abstract: A device for detecting fissionable material such as uranium in low concentrations by interrogating with photoneutrons at energy levels below 500 keV, and typically about 26 keV. Induced fast neutrons having energies above 500 keV by the interrogated fissionable material are detected by a liquid scintillator or recoil proportional counter which is sensitive to the induced fast neutrons. Since the induced fast neutrons are proportional to the concentration of fissionable material, detection of induced fast neutrons indicate concentration of the fissionable material.

Abstract: A device for shifting the frequency of infrared radiation from a CO.sub.2 laser by stimulated Raman scattering in either H.sub.2 or D.sub.2. The device of the preferred embodiment comprises an H.sub.2 Raman laser having dichroic mirrors which are reflective for 16 .mu.m radiation and transmittive for 10 .mu.m, disposed at opposite ends of an interaction cell. The interaction cell contains a diatomic molecular gas, e.g., H.sub.2, D.sub.2, T.sub.2, HD, HT, DT and a capillary waveguide disposed within the cell. A liquid nitrogen jacket is provided around the capillary waveguide for the purpose of cooling. In another embodiment the input CO.sub.2 radiation is circularly polarized using a Fresnel rhomb .lambda./4 plate and applied to an interaction cell of much longer length for single pass operation.

Abstract: A device and method for pumping gaseous lasers by means of a microwave accelerator. The microwave accelerator produces a relativistic electron beam which is applied along the longitudinal axis of the laser through an electron beam window. The incident points of the electron beam on the electron beam window are varied by deflection coils to enhance the cooling characteristics of the foil. A thyratron is used to reliably modulate the microwave accelerator to produce electron beam pulses which excite the laser medium to produce laser pulse repetition frequencies not previously obtainable. An aerodynamic window is also disclosed which eliminates foil heating problems, as well as a magnetic bottle for reducing laser cavity length and pressures while maintaining efficient energy deposition.

Abstract: A multiple laser having one or more gaseous laser stages and one or more free electron stages. Each of the free electron laser stages is sequentially pumped by a microwave linear accelerator. Subsequently, the electron beam is directed through a gaseous laser, in the preferred embodiment, and in an alternative embodiment, through a microwave accelerator to lower the energy level of the electron beam to pump one or more gaseous lasers. The combination laser provides high pulse repetition frequencies, on the order of 1 kHz or greater, high power capability, high efficiency, and tunability in the synchronous production of multiple beams of coherent optical radiation.

Abstract: An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

Abstract: A CF.sub.4 laser for producing near 16 .mu.m radiation utilizing a line tunable CO.sub.2 laser as an optical pumping source. The device uses a cryogenically cooled optically pumped cell containing molecular CF.sub.4 gas. An optical resonant cavity formed around the optically pumped cell induces oscillations of near 16 .mu.m radiation from the .nu..sub.2 +.nu..sub.4 .fwdarw..nu..sub.2 transition in the molecular CF.sub.4 gas.

Abstract: A composite superconductor formed from a high specific heat ceramic such as gadolinium oxide or gadolinium-aluminum oxide and a conventional metal conductor such as copper or aluminum which are insolubly mixed together to provide adiabatic stability in a superconducting mode of operation. The addition of a few percent of insoluble gadolinium-aluminum oxide powder or gadolinium oxide powder to copper, increases the measured specific heat of the composite by one to two orders of magnitude below the 5.degree. K. level while maintaining the high thermal and electrical conductivity of the conventional metal conductor.

Abstract: A swivel attached to a hermetically sealed device dropped from high altits to suspend the device from a parachute and allow free rotation of the device to prevent twisting and entanglement of the parachute during descent.

Abstract: A device and method for nonresonantly Raman shifting broad band uv excimer laser radiation, which enhances preselected Stokes signals by varying the pressure of the Raman scattering medium, the focal interaction length of the incident radiation within the Raman scattering medium and its power density level. Gaseous molecular H.sub.2, D.sub.2, CH.sub.4 (methane), HD and mixes thereof, and liquid N.sub.2 are used as the Raman scattering medium to frequency shift the outputs of high power KrF and ArF lasers. A cable fed discharge with an unstable resonant cavity configuration is utilized to produce the output laser power levels required for operation.

Abstract: A method and apparatus for achieving large susceptibilities and long interaction lengths in the generation of new wavelengths in the infrared spectral region. A process of resonantly enhanced four-wave mixing is employed, utilizing existing laser sources, such as the CO.sub.2 laser, to irradiate a gaseous media. The gaseous media, comprising NH.sub.3, CH.sub.3 F, D.sub.2, HCl, HF, CO, and H.sub.2 or some combination thereof, are of particular interest since they are capable of providing high repetition rate operation at high flux densities where crystal damage problems become a limitation.

Abstract: A digital numeric VHF omnidirectional range (VOR) bearing indicator for piding a stable digital readout of VOR bearing in the presence of noise and fading signals. The device utilizes a count averaging scheme for calculating VOR bearing over a plurality of cycles. High quality filtering is also achieved by the use of phase lock loops which are used to generate low noise digital signals having a phase which matches reference and variation signals, representing VOR bearing. An exclusive "OR" gate is used to compare the reference and variation signals, after they are divided in frequency, to produce a composite signal which has a duration indicative of VOR bearing. The composite signal is then clocked, counted and averaged over a number of intervals and fed to a digital display device.

Abstract: A direct coupled linear amplifier which employs negative feedback to prov accurate and stable gain to AC as well as DC input signals. It also performs the function of a DC level shifter and can therefore be interfaced with a variety of signal sources. A constant current source added to the summing junction of the negative feedback amplifier enables the adjustment of the DC level of the output and the AC gain of the amplifier, completely independently of one another.

Abstract: The disclosure relates to a pulsed gas laser comprising an optical resonant cavity, a CO.sub.2 lasing medium, structure for containing the CO.sub.2 lasing medium within the optical cavity and a device for causing a population inversion in the lasing medium, with a novel improvement comprising structure for causing a laser pulse comprising a wavelength in the near 14 .mu.m and near 16 .mu.m range. The structure for cooling the CO.sub.2 lasing medium to less than about -40.degree. C as well is a structure for pumping the maximum inversion of CO.sub.2 molecules within the lasing medium by minimizing the population in the 010 level.

Abstract: A complex pulse repetition frequency generator for producing a pulse repeion frequency (PRF) signal having programmable stagger intervals. The device consists of a clock for selecting one of a series of standard clock pulses which are used to increment a counter. A comparator compares the accumlated clock pulses with a stagger data output signal produced by a data memory source. When the outputs are equal, the comparator produces a PRF output pulse. Two data memory bands are provided; a random access memory in which stagger data can be programmed by a series of switches, and a preprogrammed read-only memory. Address counters are used with each memory unit and provide capability for addressing selected memory locations from the data memory sources. A pulse width generator allows the operator to vary the pulse width and utilizes an injection lock oscillator to prevent jitter whenever a standard clock pulse is used which is not an even multiple of a hundred nanoseconds.

Abstract: A system for determining the proper instant of time to launch an object, h as a target or torpedo, from an aircraft to cause the object to impact a water surface at a predetermined nose-down angle, thereby preventing structural damage due to high impact forces. The system utilizes signals produced by instrumentation representative of the aircraft pitch and angular rate of pitch. The desired launch altitude and predetermined impact angle are physically set into the system by means of adjustable voltage sources. These parameters are processed in the system such that the system forms a complete electronic analogy to the physical laws which govern the motion of the free falling object. In operation, the system continuously computes the predicted impact angle based on the instantaneous inputs of the aircraft's altitude, pitch angle and pitch rate. It then compares the predicted impact angle with the predetermined impact angle.

Abstract: Isolation amplifier circuitry for driving inductive as well as resistive ds in an interchangeable circuit design. The device comprises a differential amplifier having both A.C. and D.C. feedback paths when used in both modes of operation with a capability of programmable gain.

Abstract: A device for electronically correcting detected traverse error data from a racking radar antenna and receiver so that the azimuth error signal used to drive the positioning devices for the radar antenna are proportional to the true azimuth angular error. The traverse error signal produced by the radar is adjusted for various elevations by a correction factor which is generated from the detected elevation angle and proportional to the secant of that angle.

Abstract: A device for generating a signal varying in frequency from 1 to 18 GHz at a onstant output power. The device utilizes a tracking automatic level loop and reacquire loop which provide automatic alignment of a YIG multiplier filter with a YIG voltage-controlled oscillator (VCO). Adjustability of output power level control is provided in the tracking automatic level loop with a provision for LED display when the device loses lock.

Abstract: A system for detecting the existence of a projectile within a penetration ne of a target and providing a score indication for each projectile penetrating that zone. The system utilizes a doppler signal generator, a doppler cycle detector and an intercept detector for indicating penetration. A voltage controlled oscillator in the target area provides signal information for transmission by FM telemetry. The unit for scoring the number of intercepts utilizes an FM telemetry receiver for demodulating the signal information. A hit indicator produces a score indication pulse in a manner which is highly resistant to background noise. A score indication device, controlled by the control pulse, counts the score indications and signifies intercepts by an electromechanical counter, audible signals and/or a light display.

Abstract: A system for controlling the movement in azimuth and elevation of a large mber of sun following solar energy collectors from a single central controller. The system utilizes servo signal generators, a modulator and a demodulator for transmitting the servo signals, and stepping motors for controlling remotely located solar collectors. The system allows precise tracking of the sun by a series of solar collectors without the necessity or expense of individualized solar trackers.