Abstract: Improved mode-locked optical parametric oscillator apparatus comprises a mode-locked pump laser having a cavity with a predetermined effective length l.sub.p and a parametric oscillator having a nonlinear crystal, such as lithium niobate (LiNbO.sub.3), and singly resonant mirrors spaced apart by an effective distance l.sub.o which is substantially less than l.sub.p, i.e., l.sub.p .apprxeq.nl.sub.o where n.apprxeq.5-50. The interaction of the mode-locked pump output with the nonlinear crystal produces parametric outputs at signal (f.sub.s) and idler (f.sub.i) frequencies, the parametric oscillator mirrors being singly resonant at one of those two frequencies. The parametric oscillator may be disposed either externally of or within the pump cavity and the pump laser optionally may be Q-switched.

Abstract: An improved conductively cooled laser pumping assembly comprises a metallic housing having an elliptically shaped bore in which a pump lamp and laser rod are supported along the respective focal axes of the bore. The laser rod is mounted on the tapered end of a conductively cooled metal body by resilient strap means at opposite ends of the rod and with a relatively low melting temperature solder between the body and the rod to enhance thermal contact with the rod and to accommodate the different thermal expansions of the rod and body, thereby minimizing rod strain. The elliptical bore is coated with a heat absorbing substance and contains a similarly shaped one-piece snugly fitting removable glass liner or shell.

Abstract: A pulsed solid state tunable laser comprises a Q-switched pump laser at kilohertz (kHz) pulse repetition frequencies and a non-centrosymmetric Raman crystal, such as lithium iodate (LiIO.sub.3), through which the pump beam is directed at an angle .theta. to the crystal optical axis. Stimulated Raman scattering (SRS) occurs in the crystal to produce Stokes lines at substantial average output powers, which lines react with the pump signal in the nonlinear crystal at predetermined values of .theta. to generate second harmonics (SHG) and sum frequencies (SFG) of the pump and Stokes lines which constitute visible light outputs. Changing the value of .theta. by rotating the crystal, for example, permits the apparatus to be step-tuned to phasematch the signals and produce visible light outputs at a plurality of wavelengths.

Abstract: A detector for a "Black Box" toll fraud is connected to circuits at the called party's central office and comprises a relay connected in series with the called subscriber's tip (T) lead, a fraudulent call register or indicator, and a normally open time delay switch with a timer actuated by a ringing signal on the ring (R) lead, which switch closes after a predetermined delay interval (ten seconds) to cause energizing of the register. The flow of direct current in the T lead incident to the called party going off-hook energizes the relay and deactivates the switch. The control (C) lead of the central office subscriber circuit is grounded by the off-hook state of the calling party's telephone and is connected to the register by closing of the delay switch, the indication of a fraudulent call being made by the register on removal of ground from the C lead, i.e., when the calling party goes on-hook.

Abstract: A network in a four-wire communication system for verifying the source of a call seeking access to restricted telephone channels through a toll switch prior to granting such access comprises handshake circuits on the operator and subscriber sides, respectively, of the toll switch in both pairs of transmission lines, the operator input to the toll switch being on a dedicated trunk. The handshake circuits comprise two D.C. verification signal sources, the first being connectable to the transmission line pair (T lines) on the subscriber side of the toll switch, and the second being connectable to the receive line pair (TR lines) on the operator side of the toll switch. The first D.C. verification signal is applied to the T lines on completion of the dialing and is detected, in accordance with this invention, on the operator side of the toll switch by a first detector connected to the T lines in the dedicated trunk. The output of this detector causes the second D.C.

Abstract: A starter element for a high power gas transport laser having cathode and anode electrodes connected across a constant current DC power supply comprises a wire-like conductor connected in parallel with the cathode to the negative terminal of the power supply and extending between the cathode and anode parallel to the gas flow transversely of and spaced closely to the middle of the cathode. The free end of the starter element extends approximately 1 cm. beyond the downstream edge of the cathode and, when the output potential of the DC power supply is applied, causes a breakdown of the gas due to the high field strength at the starter end, producing an electrical discharge between that end and the central portion of the cathode. This induces the main electric discharge between the cathode and anode.

Abstract: Apparatus for detecting and measuring the values of radio frequency (RF) signals comprises two intermediate frequency (IF) channels having mixers fed by local oscillators (LO) with output frequencies having a predetermined frequency difference. The LO frequencies are selected to produce IFs from overlapping or coincident RF bands which are higher and lower, respectively, than the LO frequencies. The outputs of the mixers are measured in identical frequency discriminators, respectively, and the outputs of the discriminators are compared by logic circuits which determine the presence of signals in either or both of the channels and the value of the corresponding RF signal. This receiver eliminates the need for an RF preselector for the superheterodyne process and thereby broadens the RF bandwidth receiving capability of the system.

Abstract: A plastic tie member for mounting a transducer cable on a chain link fence comprises a flexible strap having two spaced apertured heads at one end arranged, when the member is tied, to snugly clamp the cable to a fence strand while maintaining them in a physically spaced relation. The effective space between the heads is substantially the same as the circumference of the cable so as to form a pocket, when the member is in the tied position, in which the cable snugly gripped with a predetermined constant force independent of the clamping force on the fence strand. This insures against excessive clamping forces on the cable, prevents damage to cable from burrs and the like on the fence strands, and maintains an efficient vibration-sensitive coupling between cable and fence.

Abstract: The method of reducing arcing in a high power gas transport laser consists of introducing molecular oxygen into the carbon dioxide mixture in which the glow discharge takes place. The oxygen may be in pure form or may be mixed with nitrogen as in air and is admitted to the recirculating gas mixture in predetermined quantities during operation of the laser. The effect of this addition of oxygen to the circulating gas mixture is to prevent the formation of oxide coatings on the copper electrode surfaces, and specifically on the cathode, thereby eliminating this cause of arcing in the laser.

Abstract: A pulser circuit produces pulses of broadband radio frequency (RF) electromagnetic wave energy that are coupled through a hybrid to a transmit-receive antenna which is contiguous with the ground. If a transmitted pulse is incident on a conductive wire in the ground, a ringing is set up in it. The wire retransmits the electromagnetic wave signal with the energy concentrated at the ringing frequency. Signals received by the antenna are coupled through the hybrid and selectively passed by a gate circuit to a processor. Signals passed by the gate are combined with a local oscillator signal in a mixer to produce an intermediate frequency (IF) signal that is displayed on an oscilloscope. A concentration of energy at a particular frequency on the oscilloscope display is an indication that a wire is in the ground below the antenna. The operation of the pulser and the gate are controlled by timing pulses from a clock circuit.

Abstract: An acousto-optic bulk wave Bragg cell having a transparent piezoelectric body and a single-layer interdigital transducer (IDT) signal input array on one surface of the body is adapted to be connected to a microwave (> 1 GHZ) energizing source for launching primarily bulk shear acoustic waves in the body transversely of the plane of the input surface. This Bragg cell is a signal transducer which converts the microwave input signal into an optical wavefront having spatial modulation directly proportional to the input signal and is utilized to diffraction modulate a laser beam directed through the cell transversely of the direction of acoustic wave propagation.

Abstract: An automatic alternator for a priority circuit comprises one or more flip-flop circuits connected to the channels of the priority circuit by a plurality of AND gate means which are responsive to outputs of the flip-flop circuits and of the priority circuit channels to alternate the servicing of successive simultaneous signals at two or more requesting ports. The flip-flop circuit input is connected to the requesting ports through an AND gate and changes its operating state in response to the presence of two simultaneous signals at the requesting ports and to a cyclically occurring clock input to the flip-flop circuit. When the operating state of the flip-flop circuit is changed to the alternating mode, the signal at the requesting port served by the priority circuit channel during the preceding cycle is blocked from that channel and another request signal appearing simultaneously at the remaining port or ports is applied to the other channel or channels.

Abstract: This invention relates to a system and method for determining velocity, direction, position, profile and confidence information of a target such as an intruder from alarms generated by the intruder passing by an array of spaced sensors. The system comprises a processor, the primary element of which is a velocity-position matrix comprising a plurality of information storage cells in the form of counters. The cells are arranged in a plurality of adjacent rows and adjacent columns corresponding to target velocity and position, respectively. Each sensor alarm is entered as a count into cells in those columns which correspond to sensor deployment and the count in each cell is shifted to the adjacent cell in the same row by auxiliary equipment at different rates for the different rows to provide a velocity determination capability. Counts are subtracted from the cells in the columns corresponding to sensor locations when no alarm is given by the particular sensor.

Abstract: Arc detection and control apparatus for a high power high voltage gas laser with a constant current power supply comprises a circuit responsive to changes in voltage across the laser electrodes for disconnecting the power supply when the voltage change exceeds a predetermined limit. The circuit monitors a small proportional value of the interelectrode voltage through an optical coupler and has a multiplier circuit for converting detected voltage changes and the differential thereof into pulses with a constant amplitude for fixed percentage changes of the electrode voltage and into pulses with increasing amplitudes for proportionally greater electrode voltage changes. This circuit normalizes and filters the resultant pulses and permits them to be compared to a reference voltage in a comparator circuit. When the pulse amplitude exceeds the value of the reference voltage a control apparatus is actuated which disconnects the power supply from the laser electrodes.

Abstract: This invention concerns a circuit which decreases the time required for certain phase-locked loops to pull in, that is, the time for the frequency of the oscillator which the loop controls to go from some initial error to some specified smaller error. The circuit is utilized with a loop employing an integrating element in the loop filter in conjunction with a logic circuit for indicating out-of-lock condition plus the sign of the frequency error and utilizes a source of direct current (DC) which is connected to the loop filter so as to increase the rate of change of the correction signal to the controlled oscillator and thereby speed-up tuning of the oscillator to the desired frequency.

Abstract: An apparatus for initiating electrical discharge in a gas transport laser having two or more sets of electrodes comprises a pulse generator connected to both sets of electrodes. The pulse generator comprises an alternating current (AC) source connected to the primary windings of two transformers having secondaries connected to the sets, respectively of electrodes. By energizing the transformers after the application of a direct current (DC) voltage across the electrodes of each set, a discharge across the sets of electrodes occurs simultaneously for a balanced starting of the lasing action.The invention also comprehends the method of starting a laser having a plurality of sets of electrodes consisting of the steps of applying a DC potential across each set of electrodes and transmitting at least one voltage pulse simultaneously to one of the electrodes of each set to produce simultaneously an electrical discharge between all sets of electrodes.

Abstract: A seismic and pressure wave sensor adapted to be buried in the earth to detect disturbances comprises a deformable tube containing an incompressible liquid in which a force-responsive transducer is immersed. The output of the transducer is an alternating signal having spectral components corresponding to both seismic (10-100 Hz) and pressure (< 1 Hz) type earth vibrations produced by human footsteps remote from and near to the buried sensor. In order to provide perimeter protection, an even-numbered plurality of such sensors are arranged in a row along a single curved or straight line and are electrically connected in parallel with the polarities of successive transducers reversed. A single processor connected to the outputs of such plurality of sensors has frequency-separated band-limited channels for isolating and detecting seismic and pressure signals, respectively, and for audibly, visually or otherwise indicating the pressure of either or both signals.

Abstract: Continuous wave (CW) output power from a gas transport laser is substantially increased by disposing a plurality of parallel cylindrically tubular cathodes in the main stream transversely of the direction of gas flow and spaced above a coextensive segmented anode in the opposite wall of the channel. Ballast resistors are connected between the cathodes, respectively, and the power supply to optimize the uniform arcless distribution of current passing between each cathode and the anode. Continuous output power greater than 3 kw is achieved with this electrode configuration.

Abstract: Continuous wave (CW) output power from a gas transport laser is substantially increased without arcing by the use of a tubular cathode having a racetrack-shaped cross section and disposed in the main stream of gas flow through the laser channel transversely of the direction of flow and spaced above and upstream from a coextensive segmented anode in the opposite wall of the channel. The racetrack-shaped cross-sectional configuration of the cathode provides maximum electrode surface for generating a glow mode electric discharge and also induces turbulence at that surface so as to support high current densities without arcing. Continuous output power greater than 3.5 KW is achieved with improved efficiency with this electrode configuration.