Abstract: A pulse expansion and compression system, especially useful for radar rang, comprising a pulse coder for expanding an input pulse and a pulse compressor of the matched-filter type. The coder consists of a plurality of delay stages into which the input pulse is fed, a discrete Fourier transform (DFT) circuit to which the output signals of the delay stages are fed by way of respective phase weights and for which every other frequency port is inverted prior to entry to a time-dispersion-means (TDM) comprising an arrangement of adders interconnected by delay stages for differently delaying the output signals from the DFT. The TDM output is fed to a phase modulator and then to the transmitter.The echo signals are conjugated, time-inverted, and passed through the same DFT as the input pulse signal by way of the phase weights. The outputs of the DFT are then inverted at every other frequency port and passed through the TDM, but this time in time-inverted order.

Abstract: A device for detecting small amounts of a chemical such as ammonia, and other ammonia-like molecules such as hydrazine or pyridine, in air and in other gases is disclosed. A capillary tube serves as a multiple total reflective medium for an optical beam from a light-emitting diode. The outer surface of the capillary tube is coated with a dye which, when exposed to the chemical, changes color so that the multiply reflected light is modified. The resultant change in the output light intensity from the capillary tube is photodetected and recorded to sense the presence of the chemical. When the chemical is removed, the dye returns to its original color so that the device can be reused.

Abstract: A device for fabricating a target of a lasing material and a pump material or lasing at X-ray wavelengths wherein one of the materials occurs naturally as a gas. A substrate of the other material is cooled below the freezing point of the one material occuring naturally as a gas. Then a gaseous atmosphere of the latter material is supplied to the cooled substrate so that a frozen layer of the latter material condenses onto the substrate to form the target.

Abstract: A pulse expansion and compression system, especially useful for radar rang, comprising a pulse coder for expanding an input pulse and a pulse compressor of the matched-filter type. The coder consists of a plurality of delay stages into which the input pulse is fed, a discrete Fourier transform (DFT) circuit to which the output signals of the delay stages are fed by way of respective phase weights and for which every other frequency port is inverted prior to entry to a time-dispersion-means (TDM) comprising an arrangement of adders interconnected by delay stages for differently delaying the output signals from the DFT. The adders are connected in N/2-fold cyclically permutated order to the frequency ports, where N is the number of frequency ports if that number is even, and N is the number of frequency ports less one if that number is odd. The TDM output is fed to a phase modulator and then to the transmitter.

Abstract: An optical processor that can compute the moments of a two-dimensional image in parallel. The image is placed at the plane of a holographic mask which is disposed in the front focal plane of a Fourier-transforming lens and each of the desired moments is found at a respective one of a plurality of photodetectors arrayed in the back focal plane of the lens.

Abstract: A mirror antenna employing a continuous mirror without a hole. A feed horn nd an electromagnetic lens, located behind a rotatable twist reflector (the mirror), collimates a beam toward a polarized reflector located near the twist reflector and tilted to aim energy toward the twist reflector. Energy reflected back toward the polarized reflector from the twist reflector passes through the polarized reflector to free space.

Abstract: A quasioptical gyroklystron for generating high power quasioptical radiation. A mildly relativistic electron beam gyrating in a static magnetic field is passed through a first open mirror resonator where a small change in the transverse electron energy takes place (either an increase or decrease depending on the relative phase between the electron gyration and the resonator wave fields). This small change than leads to slower (or more rapid) gyration of those electrons that have gained (or lost) energy in the first resonator. The length of the drift region between the first and a second open mirror resonator is adjusted so that rapidly gyrating electrons overtake slowly gyrating ones at the entrance to the second resonator. Thus the particles arrive at the second resonator strongly bunched in gyration phase. The fields in the first resonator are generated by feedback of a small amount of energy from the wave mode in the second resonator with a .pi.

Abstract: An orthogonalizer wherein a series of complex digital numbers is received, each number having correlated (non-orthogonal) real and imaginary parts; a weight is established which is a measure of the correlation; the product is formed of one of the parts of one of the received complex numbers with the weight; and the product is subtracted from the other part of the one received complex number to decorrelate (orthogonalize) the real and imaginary parts thereof.

Abstract: A multiwavelength multiplexer-demultiplexer constructed from units each cble of multiplexing or demultiplexing two wavelengths. As many such units as required can be interconnected to form multiplexer-demultiplexers of any number of wavelengths. Each two-wavelength multiplexer-demultiplexer unit includes a four-port power divider, a four-port phase shifter having two ports connected to two ports of the power divider, and another four-port power divider having two ports connected to two ports of the phase shifter. The power divider may be a single-mode optical fiber directional coupler, or a half-silvered mirror beam splitter. The phase shifter may include a pair of single mode optical fibers or a pair of oppositely disposed mirrors.

Abstract: A dual band mirror antenna employing a continuous mirror without a hole. e-by-side feeds for each band and an electromagnetic lens, located behind a rotatable twist reflector (the mirror), collimate beams toward a pair of polarized reflectors located near the twist reflector and tilted to aim the reflected energy toward the twist reflector. One polarized reflector is reflective at the higher radiofrequency band and transparent at the lower radiofrequency band. The other polarized reflector is reflective at both bands. Energy directed back toward the polarized reflectors from the twist reflector passes through the polarized reflectors to free space.

Abstract: A device for converting a signal voltage into a multi-bit digital word that efines the voltage magnitude and polarity. The input voltage V to be digitized is used to control the frequency of a voltage controlled oscillator, whose output is defined to be f=f.sub.o +kV. The signal out of the voltage controlled oscillator is fed to differential delay line filters that permit all digits to be derived in parallel. The filters comprise pairs of delay lines of unequal length, each pair feeding a respective phase detector whose output is amplified, and diode-rectified and limited. To increase the accuracy of this device, an automatic frequency control loop can be incorporated to control f.sub.o. This loop zeros V occasionally and reads the output digital word to measure the frequency error and add a correcting voltage to the input voltage V when it is not zeroed for the measurement.

Abstract: A wideband trap-loaded monopole antenna having small structural dimensions n a plane normal to the polarization axis. The traps are resistively-terminated quarter wavelength transmission lines. The locations and anti-resonant frequencies of the traps are selected to make the antenna's input impedance and gain nominally uniform parameters with respect to frequency.

Abstract: A variable-gain, constant output power amplifier which generates an output rf signal of constant power level in response to an input rf signal of varying power level. The amplifier gain is preadjusted by a plurality of feedforward automatic-gain-control circuits to provide the constant output power. The amplifier comprises five dual-gate MESFET signal-amplifying stages. The first and last stages do not have built-in automatic-gain-control. The first stage is provided for preamplification prior to sampling the input signal, and the last stage is provided for setting the level of the output power externally. The signal at the input of each of the middle three stages is sampled through a coupler and detected and processed at video frequencies to dynamically preadjust the gain of the next signal-amplifying stage.

Abstract: A method and apparatus for determining the phase angle of the sensitivity of a hydrophone H to be calibrated. The method comprises positioning in a straight line a transducer P, the hydrophone H, and a reciprocal transducer T that can be used both as a hydrophone and a projector; determining the phase angles of a set of voltages and currents; and finding the phase angle of the sensitivity from the former phase angles. The apparatus includes a framework for positioning P, H and T in a straight line, an electronic system for monitoring the voltages and currents, and a programmed computer for performing a single-point DFT.

Abstract: A method for making an airtight seal between a pair of insulator elements, uch as glass plates, without destroying any fine structure etched in the insulator elements. A thin metal film is deposited on one of the elements to be sealed and then placed in intimate contact with the other element to be sealed. The elements are then heated to a temperature well below their softening point, but high enough to significantly enhance the ion mobility in the insulator. A voltage is applied across the interface and the resulting anodic reaction consumes the film at the interface while producing a strong hermetic bond between the insulator elements.

Abstract: A passive maser wherein control of the cavity and control of the oscillator on the line of stimulated emission operate in a shared-time mode. A control circuit acts on the injected signal by way of a programmable synthesizer, the injected signal then assuming the successive values .omega..sub.L.sup.+, .omega..sub.H, .omega..sub.H and .omega..sub.C.sup.+, .omega..sub.H and .omega..sub.C.sup.-, .omega..sub.L.sup.-, .omega..sub.L.sup.+, etc. in stages. .omega..sub.H is centered at the line of stimulated emission; .omega..sub.L.sup.+ and .omega..sub.L.sup.- which are symmetrically shifted interrogate the sides of the emission line; and .omega..sub.C.sup.+ and .omega..sub.C.sup.- which are further symmetrically shifted interrogate the sides of the cavity resonance. The control circuit periodically inhibits the detection action used for controlling the oscillator, and the detection action used for controlling the cavity is carried out only during the inhibition period.

Abstract: Method and apparatus for determining when a lubricant has reached the end its useful life due to oxidative degradation. The apparatus continuously monitors the evolution of gaseous emission from the lubricant when subjected to oxidizing conditions, and detects the increased gas emission accompanying oxidative breakdown.

Abstract: A test signal waveform detector that includes a fiber optic interferometer wherein the phase difference of the two parts of a split laser beam is modulated by the waveform of a sinusoidal test signal which is to be detected and by the waveform of a sinusoidal reference signal, and the two parts of the split beam are recombined and mixed on the face of a photodetector. A signal conversion circuit converts the ac signal produced by the photodetector to another ac signal that carries the test signal information as an equivalent frequency modulation, and a demodulator extracts the test signal information from the latter ac signal.

Abstract: An intense, space-charge-neutralized, pulsed ion beam is used to heat a metically-confined plasma, such as a tokamak plasma, by injecting the ion beam into the plasma along a trajectory that is generally tangential to the confining magnetic field. The ion beam inductively generates a plasma return current so that no net current is produced. As the ion beam drifts in the plasma, the confining magnetic field is transformed into one which can trap the ion beam at the center of the plasma. Once the ion beam is trapped, the plasma return current is cancelled by transformer action to produce a net current which is carried by the ion beam alone. The beam transfers its energy to the plasma by classical collisions with the electrons and ions of the plasma. Heating of the plasma can be sufficient to produce a breakeven condition or ignition.

Abstract: A magnetron in which the space between the anode and cathode contains a h mobility semiconductor. The structure is non-cylindrically symmetric because the anode and cathode are placed on top of the semiconductor. The electrons are injected into the substrate and then accelerated toward the anode members where they are extracted. Alternate anode members are strapped together to favor excitation of the .pi.-mode.