Abstract: A multi-layer composite brazing alloy useful in mine drills for attaching hardened bits, such as tungsten carbide, to bit holders made of steel and the like, comprises two outer layers of a brazing alloy bonded to an inner layer or core of iron or nickel. While a wide variety of brazing alloys are useful as the outer layers, a cost preferred alloy is AMS-4764 (in percent by weight 9.5 Ni - 52.5 Cu - 38.0 Mn) having a melting range of 880.degree.-925.degree. C. This is approximately 40% less than the melting temperature of the iron or nickel core which, therefore, is not susceptible to melting and alloying with the outer layers when the brazing furnace temperature fluctuates during the brazing operation. On cooling, the ductile iron or nickel core absorbs stresses due to dissimilar thermal expansion coefficients of the carbide tip and the holder and prevents cracking of the joint.

Abstract: An acousto-optic mode-locked laser comprises a piezo-electric, acousto-optic crystal disposed within the cavity of a laser in the path of the laser beam, and a radio-frequency energized interdigital transducer (IDT) array coupled to the crystal so as to launch bulk shear waves in the crystal for a limited number of interactions with the laser beam. The IDT is mounted on a first plane surface of the crystal opposite from a second plane surface thereof which is disposed at an acute angle .theta. to the first surface and which is nominally parallel to the laser beam. Bulk shear waves are launched in the crystal by the IDT at the first surface at the angle .theta. to a normal to that surface with the forward wave traversing the laser beam perpendicular to its axis and being reflected back through the beam by the opposite or second crystal surface to form standing waves which modulate the beam.

Abstract: An improved flexible ceramic tape consists essentially of ceramic powder and a water soluble binder of polyacrylic acid polymer and glycerol. Additions of small amounts of polyvinyl pyrrolidine to this binder improves the flexibility of the resulting tape. The ceramic powder consists of alumina. The invention also comprehends the method of making this tape consisting of the steps of preparing a slip or mixture of an aqueous solution of polyacrylic acid polymer and glycerol together with the ceramic powder, casting this slip on a substrate to a predetermined uniform thickness, and drying the mixture. The tape may be removed from the substrate or allowed to remain mounted on it.

Abstract: A flexible brazing alloy tape with a binder having less than 3% by weight total organic content and no more than about 1% by weight residual ash after melting is provided by use of a polyacrylic acid polymer, glycerol and water as a vehicle in which the powdered alloy is dissolved to form a slurry prior to casting. The polyacrylic acid polymer has a relatively low viscosity defined by a molecular weight of about 450,000. The slurry is deposited on a substrate and is dried and the resulting flexible low organic self-supporting tape is removed from the substrate to be formed into desired shapes as preforms for brazing. Alternatively a brazing alloy tape comprising a binder having a similarly low total organic content is produced by mixing the powdered alloy with polyvinyl alcohol, glycerol and water and thereafter casting the tape as described above.

Abstract: A solid state voltage regulator circuit having an output with absolute voltage change per degree centigrade temperature dependence comprises a voltage regulator having a forward control loop for sensing changes in regulated output voltage, and a temperature transducer having an output voltage connected to the forward loop and adapted to change the sensed regulated voltage input to the regulator in direct proportion to the absolute ambient temperature. The transducer output is connected to the forward loop by an amplifier and the circuit is readily adapted to any desired linear temperature dependence by adjustment of the gain of the amplifier.

Abstract: A capacitance intrusion detection system for use with a metal object or objects insulated from ground comprises a circuit for cyclically charging and discharging the object at a relatively low frequency, for example, less than 500 Hz, and simultaneously integrating the charge on the object to develop a DC voltage proportional to the capacitance of the object. The integrating network is AC coupled to a bandpass filter which passes signals having frequencies corresponding to changes in capacitance of the object caused by an intruder and these signals are applied to a threshold circuit for activating an alarm when an intrusion occurs. Tamper alarm circuits are provided to detect unauthorized disconnection of any portion of the protected object (decrease capacitance) or the addition of capacitance in an attempt to defeat the system.

Abstract: A vertically-polarized log-periodic monopole antenna comprises two closely spaced arrays of elements over a ground plane and connected to a balanced feed source, i.e, the arrays are separately excited out of phase by the source. The elements of each array taper from minimum dimensions at the feed end to maximum at the other end in progressive increments of a predetermined ratio .tau. and are open at their inner ends proximate to the ground plane. Each array preferably comprises an electrically continuous wire-like conductor configured to define the profile of the elements and to constitute the interelement connecting lines. Preferred shapes of the elements are trapezoidal, pseudo-trapezoidal and triangular. The antenna provides very broadband (20 to 750 MHz) frequency independent performance at minimum VSWR (<2.0 to 1) and has non-critical design parameters.

Abstract: A log-periodically loaded monopole antenna comprises a plurality of longitudinally log-periodically spaced longitudinally tapering linear radiating elements in a vertical plane, a meander transmission line (meanderline) in a second plane perpendicular to the vertical plane and extending longitudinally on opposite sides of the plane of the elements and intersecting successive elements at the cross-over points, and a straight transmission line or shunt in the second plane interconnecting the junctions of the elements and the meanderline. The addition of this shunt substantially eliminates the large gain drop-out characteristic of this antenna, the voltage standing wave ratio being reduced from an average of 6:1 to less than 1.6:1. In one embodiment the elements are pivotally connected to the transmission line for pivoting in the vertical plane to permit collapsing of the elements toward the plane of the transmission line when required due to space limitations.

Abstract: The invention is an aluminum base brazing alloy for brazing assemblies of titanium and titanium alloys with excellent wetting capability characteristics and the capability of forming large fillets at a relatively low temperature of 1470.degree. F., consisting essentially by weight of about 2.0% to 6.0% silicon, 2.5% to 6.0% tin, 13.0% to 28.0% copper and the balance aluminum.

Abstract: A ring-down or non-dial subscriber telephone such as a freeway emergency telephone is connected to automatic electronic switching (EAX) equipment for interconnection with an emergency operator by an interface circuit having a polarity-sensitive full-wave bridge controlling voice connection of the telephone to the operator. Actuation of the bridge is controlled by a current sensitive controller connected in series with the originating loop containing the freeway telephone. The bridge monitors the on-hook and off-hook states of the called telephone and energizes alarm circuitry upon failure of the calling telephone to go on-hook within a predetermined time after the called telephone goes on-hook. The circuit also has a capability of monitoring current flow in the originating loop containing the calling telephone and of energizing a common alarm circuit in the EAX equipment in the absence of such current flow.

Abstract: A physically compact gas transport laser operable at high pulse rates (greater than 1 kHz) in a high vacuum (greater than 10.sup.-5 Torr) is achieved by flowing the active gas at high velocity (greater than 50 m/sec) between two discharge electrodes in a hermetically sealed housing containing squirrel cage type blowers, a heat exchanger and the laser electrodes. A pulse forming network and blower motors are mounted externally of the housing as is the optical resonator assembly. A central partition divides the housing interior into upper and lower gas flow channels. The blowers are located in the lower channel at the housing end downstream from the electrodes and are rotatable in a plane parallel to the plane of the partition. The heat exchanger is located at the opposite end of the housing and both cools and stabalizes the flow of the circulating gas.

Abstract: An optical resonator assembly mounted externally on a hermetically sealed gas transport laser comprises a U-shaped tubular bench secured to the laser housing top wall and having an elongated beam with legs extending at right angles to opposite ends, respectively, of the beam adjacent to the front and rear walls of the laser housing. Flat bases depend from the respective bench legs and overlay optical windows in the front and rear housing walls through which the internally generated laser beam passes. The bases have openings aligned with the windows, respectively, and adjustably mount mirror support plates, respectively, adjacent to those openings. Mirrors attached to the support plates define the laser optical cavity. The bench is a rigid tubular structure providing stable support for the optical components and also constituting a fluid conduit for carrying cooling air to minimize thermally induced dimensional changes.

Abstract: A silver based brazing alloy having a composition in percent by weight of 5 to 15 germanium, 8 to 18 zinc, 5 to 39 copper and the balance silver has a wide melting range and a high degree of fluidity when molten and is especially suited for wide-gap brazing of steel assemblies in food handling equipment where cadmium containing brazing alloys cannot be used because of their toxicity.

Abstract: An electrode assembly for a compact high vacuum pulsed gas discharge laser comprises an elongated cathode and a coextensive anode spaced apart in a direction transversely of the flow of gas to define a discharge gap. Each of the electrodes is connected at a plurality of equally spaced points along its length to a like number of conductive rods which extend through the top wall of the laser housing for connection to a power source. The cathode comprises a carrier bar directly attached to said rods and a cathode bar adjustably secured to the carrier bar for vertical movement toward and away from the anode to permit attainment of a uniform discharge gap throughout the length of the electrodes. Preionization of the discharge gap is achieved by means of a conductive sleeve electrically connected to one of the electrodes and disposed against the inner surface of a dielectric tube which contacts the other electrode throughout its length.

Abstract: The apparatus is connected to the mounting cord of a subscriber telephone set and determines whether or not certain clandestine circuits or devices are connected across pairs of conductor lines in the mounting cord. The apparatus generates a pulse voltage and a holding signal which are applied to these lines in order to sustain conduction of breakdown devices, if any, that are connected across the lines. If detectors in the apparatus sense that the line impedance is between predetermined upper and lower limits equivalent to open and short circuits when the holding signal is applied, an indication is made that such circuits or devices are connected across the telephone lines.

Abstract: Thermal lensing effects in a conductively cooled optically pumped laser rod are compensated by limiting the width of thermal contact between the rod surface and its supporting heat sink to an arc width of 70.degree. to 80.degree. and utilizing a simple cylindrical laser cavity mirror or mirrors. This limited heat sink contact produces nearly parallel isotherms in the rod which react with the laser beam so that it may be readily focused by a cylindrical beam focusing means in the laser optical resonator.

Abstract: A translating mechanism for accurately positioning and locking an object relative to a reference plane comprises a base plate which defines the reference plane and a platform supported parallel to the base plate for movement in a direction perpendicular to the plane of the base plate. A spring between the base plate and platform urges the latter away from the plate and an adjustment screw operably connected to the platform and to the plate permits changing of the spacing between the platform and plate against the bias of the spring. Nestable U-shaped arms pivotally connected to the plate and platform, respectively, and to each other directly slideably engage the plate and platform, and maintain parallelism therebetween during their relative movement. A flexible end wall adjacent to the platform releasably clamps the platform against the opposite end wall to lock same in any position within its range of movement. This also minimizes the load path length between platform and base.

Abstract: The utility of a coaxial electret cable transducer as a hydrophone at shallow depths (low hydrostatic pressure) is extended for operation at substantially greater depths (high hydrostatic pressure) by the combination of the electret with a polymer material having piezoelectric properties, i.e., a piezoid. The electret and piezoid are separate flexible materials radially stacked within the cable or alternatively and preferably constitute a single material formed to have both electret and piezoelectric properties. One substance useful as the piezoid or as the electret-piezoid combination is polyvinylidene fluoride (PVF.sub.2).The invention also comprehends the method of measuring underwater soundings at either low or high hydrostatic pressures with the aforementioned coaxial cable as an electrostatic transducer by measuring electrical signals generated across the cable conductors when the ambient pressure is low and as a piezoelectric transducer across the conductors when such pressure is high.

Abstract: A laser pumping assembly with a housing having a removable heat resistant glass liner or shell enclosing a pump and a laser rod comprises removable glass or quartz plates over opposite ends of the shell together with a heat absorbing shim between each end plate and an adjacent heat conductive support plate attached to the housing. The outside surface of each end plate is coated with a dielectric layer which reflects the desired wavelength of pump lamp radiation inwardly of the shell toward the laser rod and transmits undesired wavelengths to the adjacent shim. The shims are held tightly against the end plates and pass heat from the unreflected pump lamp radiation to the respective support plates for dissipation in the cooling system.