Abstract: Calibration means, including an optiosolator, for a hydrophone preamplifier hich couples to a remote DC supply source and a remote load through a long, two-wire cable. The output signal of the optoisolator is fed to the amplifier in series with the hydrophone output signal, the input to the optoisolator being an AC calibration signal. In an array of preamplifiers, the same calibration signal is fed to all the preamplifiers by connecting the optoisolators in series with each other and the source of the AC calibration signal.

Abstract: A fluorinated phthalonitrile of the general formula: ##STR1## wherein R' is F or CF.sub.3, R is (CF.sub.2).sub.p, m is 1 or 2, n is 1 or , p is an integer from 3 to 30, x is 1, 2, or 3, y is 1, 2, or 3 and z is 0 or 1 is prepared by reacting 4-iodophthalonitrile with the appropriate diiodide in the presence of activated copper in a dipolar aprotic solvent. Heating this phthalonitrile to a temperature from about its melting point to about 285.degree. C. produces a polyphthalocyanine resin. If a salt or metal is added prior to the heating, a metal or salt-coordinated polyphthalocyanine is produced. Polyphthalocyanines are useful in coatings, laminates, filament windings, castings, and structural composites.

Abstract: A spiral passage chemical converter-heat exchanger formed by a cross-sectally rectangular housing containing a pair of rows each containing a plurality of side-by-side passages. The rectangular housing is wound into a spiral with the innermost row forming inlet passages and the outermost row forming outlet passages. Thermal contact exists between inflow passages and outflow passages. The outer end of the spiral is connected with an inlet and an outlet. The inlet joins the innermost row of passages and the outlet joins the outermost row of passages. The inner end of the spiral is capped, with a common wall separating the upper and lower passages slotted so that fluid flows from the inlet passages to the outlet passages. As can be seen when the structure is in a spiral, the inlet passages are between the outlet passages with the outlet passages forming the outer exposed surface of the spiral and the inlet passages forming the surface of the opening through the spiral at the center.

Abstract: A device for producing extended plasmas for x-ray lasers. In an evacuated using, a pair of tungsten blocks are placed just above a target surface and spaced apart to form a channel. A high power laser beam is focused to a point on the target creating a plasma between the blocks. As the plasma expands away from the target in the z-direction, the tungsten blocks confine the plasma in the y-direction and plasma species of higher stages of ionization are formed into a jet of rectangular x-y cross section in the z-direction by the blocks. The plasma remains confined in the y-dimension or is focused in this direction above the blocks where sufficient amplification occurs to provide x-ray lasing along the x-axis.

Abstract: A stimulated emission device operative in the ultraviolet and soft x-ray regions. A high-power infrared laser is focused on a slab target vaporizing the material and generating highly stripped target ions with varying velocities. Just prior to laser initiation, a gaseous environment of helium, hydrogen, argon or neon is injected to surround the target (e.g., carbon) at a pressure of from 1-10 Torr. The injected gas and associated electrons modify and mix the interacting particles originating from the vaporized target. Ion-atom resonance, charge-transfer reactions take place to form excited-state ions to produce amplified stimulated emission in the 300-800 Angstrom region.

Abstract: A method and apparatus for spraying a surface which comprises: introducing into a laser beam, a powder with a vapor pressure from 10.sup.-2 to 10.sup.-1 atm. in excess of the ambient pressure at a temperature up to about 500.degree. C. above the melting point thereof and with a heat-absorption coefficient from 0.2 to 1; and passing the laser beam over said surface. Since the method and apparatus can coat or alloy or dope a surface, a wide variety of protective coatings can be fabricated.

Abstract: It is shown that the interrogation repetition period (IRP) of an interrogr can be recognized by a transponder and then used by it to both determine when the interrogator has elicited a predetermined number of replies called an adequate response and limit the interrogator to that number during each scan. This form of reply limiting by a transponder requires absolutely no change in the type of signals transmitted. Logic circuits that perform the required functions are provided.

Abstract: The invention is a magnetically tunable bandpass filter for use in the miwave regions, particularly for frequencies between 0.1-4 GHz. A magnetically tunable bandpass filter is a filter which will pass only certain frequencies from one conductor to a separate conductor depending upon the frequency band and the magnetic field applied across the filter. The tuning of the center frequency can be achieved at relatively fast electronic switch times. The center frequency is the frequency at which the most coupling exist due to the applied magnetic field. Two striplines are placed at 90.degree. relative to one another with one end of one stripline overlapping one end of the other with the overlapped ends connected to ground. A disc of ferromagnetic material is placed between the two striplines.

Abstract: A circuit for processing the azimuth error video signal of a monopulse rever in an aircraft to separately but simultaneously display the heading and position of the craft. The azimuth error signal is simultaneously applied to a sample-and-hold (SAH) circuit, a delay means and a one-shot multivibrator (MV). The MV opens the SAH to accept the first ground-transmitter signal in a sequence, the SAH charging a capacitance to the magnitude of the signal, and then prevents the SAH from accepting any further signals in the sequence. The output of the SAH is subtracted from the delayed signal to obtain a video signal indicative of aircraft position, and the output of the first subtracter is subtracted from the delayed signal to obtain a video signal indicative of the aircraft heading.

Abstract: A solenoid comprising several, discrete, coaxial, circular, superconducting coils provides a magnetic field which decreases radially to an absolute minimum intensity to focus the ions as they are accelerated to the end of the non-relativistic velocity range. As the ions are further accelerated to relativistic velocities, the magnetic field increases radially from the absolute minimum intensity to compensate for the relativistic increase in mass. The revolving ions are accelerated by repeated passage through an electric field which is established in radially-directed resonator horns. The accelerating structure and the associated electric field reinforce the focusing provided by the radially-increasing magnetic field.

Abstract: A system and method of detecting stray electrical currents that cause corrosion on metallic structures submerged in electrolytic media. The system makes use of a plurality of metal plates in an arrangement so they will be bipolar electrodes in a stray current field and the stray currents are determined by the color of the plates. The amount of stray currents are determined by the amount of metal loss over a period of time. Plates may be placed about a ship's hull, or other submerged structures, or suspended in an open area of solution to locate areas of stray currents.

Abstract: A polphthalocyanine with the structure formula: ##STR1## prepared by mixing SnCl.sub.2.2H.sub.2 O with N, N'-bis(3,4-dicyanophenyecane diamide of which the structural formula is: ##STR2## heating the mixture to a temperature from about 175.degree. C. to about 185.degree. C. for about 15 to 20 minutes to form a resin; and curing the resin at a temperature from about 190.degree. C. to about 230.degree. C. The polyphthalocyanine is useful as an adhesive, as a matrix for glass or carbon-fiber reinforced composites, and as structural material.

Abstract: A reflex tetrode device for efficiently generating intense, pulsed unidirional ion beams. The device includes two thin, semitransparent anodes spaced from a real cathode which is maintained at ground potential. The first anode is spaced from and faces the real cathode. The second anode is spaced a short distance from the first anode and a virtual cathode is formed beyond the second anode when a sufficiently high electron current flows from the real cathode and through the anodes. The anodes are ring-like or disc-like structures secured to the edges of a support member with their planes perpendicular to the axis of the device between the real and virtual cathodes. The anode structure (i.e., the support member together with the two anodes) is connected to a pulsed high-voltage generator which is operated in positive polarity. Consequently, both anodes are at the same positive potential.

Abstract: A system for measuring, in conjunction with a GCA radar, the crab angle of n aircraft which is making its landing approach above a runway. A loop antenna mounted on the craft transmits an audio-frequency electromagnetic wave to two sets of crossed receiving loops, each set mounted at one side of the runway. A line joining the centers of the loops makes a 45.degree. angle with the plane of each loop. The outputs of the loops in each set are subtracted from each other, amplified, detected and rectified and then differentiated to provide a pulse output indicating the zero point of the subtraction, i.e., the time when the H-field vector is at an angle of 45.degree. to the plane of each of the loops in the set providing the zero-indicating pulse output. The zero-indicating pulse outputs are fed to a time interval counter which determines the time interval between them.

Abstract: A fiber optic hydrophone for use as an underwater electroacoustic standard. The hydrophone includes a fiber optic acoustic wave detector in one end of the hydrophone which is subjected to incident acoustical waves. A similar fiber optic is in an acoustically isolated compartment where the optic fiber is not affected by the incident acoustical wave. Comparison of light passing through each coil will determine incidence of an acoustical wave on the detector fiber.

Abstract: An improved variable light beam power attenuator which uses a flat mirror d a focusing mirror fixed in a suitably movable structure. Linear movement of this structure varies the diameter of a spot of light illuminating a "diffraction-limited" aperture of a special shape. A second focusing mirror is provided to collect the "diffraction-limited" light transmitted by the aperture and to focus or collimate it. A second flat mirror may be used to re-direct the output beam. The mounting arrangement of the first two mirrors relative to the input light beam and the remainder of the power attenuator permit an all mirror system which requires only a single linear motion to change the power level of the transmitted beam. The use of an all-mirror system allows all the advantages of reflective optics over transmitting optics for high power CW (continuous wave) laser beam.

Abstract: A composite superconductor which comprises:(1) A matrix sheath of a copper-base alloy containing from about 12 to ab 20 at. % of gallium and from about 0.2 to about 6 at. % of aluminum;(2) a core in said matrix sheath, said core being of a vanadium-base alloy containing from about 1.0 to about 9.5 at. % of gallium and from about 0.1 to about 2.5 at. % of titanium; and(3) a continuous interfacial layer of V.sub.3 Ga between said matrix sheath and said core.

Abstract: A solid-state diffusion method for providing ohmic contacts to n-type Group II-V semiconductor materials, such as gallium arsenide (GaAs). The material is successively cleaned, etched, rinsed, re-etched, rinsed and placed in an oil-free vacuum. The substrate is then heated to desorb surface oxides and an epitaxial layer of germanium and a layer of nickel, or other refractory, are deposited on the substrate at specific temperatures. Next, the structure is annealed in the vacuum at temperatures sufficient to diffuse the germanium into the GaAs material and to establish an ohmic contact.

Abstract: The invention involves the measurement of the concentration of the radioisotope .sup.129 I.sub.2 in the presence of a gas. The invention uses a laser to excite a sample of the .sup.129 I.sub.2 in a sample gas chamber and a reference sample of a known concentration of .sup.129 I.sub.2 in a reference gas chamber. The .sup.129 I.sub.2 in the sample and reference gas chamber each gives off fluorescence emissions which are received by photomultipliers which provide signals to a detector. The detector uses a ratioing technique to determine the concentration of .sup.129 I.sub.2 in the sample gas chamber.

Abstract: A system for varying specific gravity of a submersible or any immersed obt under a pressurized environment which includes a compressible piston designed to collapse a certain amount proportional to the submersible's depth so that the specific gravity of the submersible or other immersed object varies and remains almost equal to the specific gravity of the surrounding medium such as water.