Abstract: A removable gasket for sealing an air-cooled hollow core module to the port of a chassis plenum for supplying cooling air includes an aluminum frame to which a thermally conductive elastomer seal is vulcanized. The gasket frame provides support for the seal and serves as a compression limiting stop for the seal. The gasket is held in alignment with the cooling channel of the hollow core module with attachment screws, greatly facilitating the gasket removal and repair of the module, and realignment with the chassis plenum port upon reassembly.

Abstract: A CO.sub.2 waveguide laser frequency modulation (FM) system which applies the Fourier series components of a triangular drive waveform selectively to the tuning PZT at one end of the waveguide and the FM PZT at the other end to achieve an improvement over the waveform than can be achieved by applying the fundamental and its harmonics to the FM PZT alone. The system applies the fundamental component to the tuning PZT and the odd harmonics to the FM PZT. The frequency-separated drive signals are applied in proper phase to the PZT's at each end of the waveguide via waveform synthesizer, frequency splitter and amplifiers. The waveform synthesizer includes a ROM containing digitized values of segments of the waveform amplitudes and a digital-to-analog converter for converting the digital ROM data to an analog signal.

Abstract: An optical beam phase shifter includes a liquid crystal cell having a common electrode on a first window and a multiplicity of parallel stripe electrodes on a second window. A multiplicity of control signals are applied between the individual stripe electrodes and the common electrode, thereby creating local variations of the refractive index of the liquid crystal molecules therebetween, which variations cause differential phase shifts across the cross section of a light beam incident thereon. An optically-refractive element, having an index of refraction greater than the index of refraction of the liquid crystal cell, is interposed between the beam and the liquid crystal cell. The refractive element, illustratively a prism, increases the angle of incidence of the beam entering the cell, thereby increasing the beam travel distance through the liquid crystal molecules.

Abstract: A laser gyro system wherein a plurality of nonplanar ring laser gyros are nested within a common supporting block of material. The nonplanar ring laser gyros have a ring path whose circumscribing volume has a size of the order of the volume of the supporting block, each ring path utilizing a portion of the volume unused by the other. In one embodiment, a cubic block contains two orthogonal tetrahedral ring laser gyros. The two rings intersect and share a common gas envelope. In another embodiment, the supporting block contains two orthohedral ring laser paths.

Abstract: A sprayable ablative coating formulation comprises a combination of a polymeric resin, a curing agent, cork flour and a vehicle such as toluene. The mixture is sprayable using conventional spray equipment. The surface to be coated is first sprayed with a primer to improve adhesion, and the mixture is than sprayed over the primed surface until a desired thickness is formed. Once cured, the coating has a uniform fine texture and thickness, providing thermal insulation for the coated surface. Pigments may be added to the formulation to acheive specified coloration of the coating.

Abstract: A dielectric resonator filter suitable for use at L-band includes a puck-shaped dielectric resonator attached directly to a dielectric substrate which is bonded to the cavity base in order to decrease vibration sensitivity while retaining a relatively high loaded Q of the dielectric resonator filter. The high value of Q is attained by the use of a low loss dielectric substrate with a dielectric constant sufficiently high that the electrical dimensions of the cavity approximate the free space or optimum model wherein the resonator is positioned at the center of the cavity. The disclosure describes a dielectric resonator filter having a loaded Q in excess of 6500 at 1.538 GHz with an insertion loss of 6 db, while maintaining a vibration sensitivity of 2.2.times.10.sup.-8 G.sup.-1. An arcuate segmented line comprising a plurality of tracks used as a coupling structure permits individual selection for each filter of the coupling, while not degrading the loaded Q value or the vibration performance.

Abstract: A quick connect/disconnect waveguide connector assembly is provided comprising first and second mating waveguide connectors. The first mating waveguide connector comprises a first outer member and a first insert disposed within the first outer member. The first insert has a mating portion having a generally conical shape truncated at a first face. The first insert further includes a waveguide slot disposed therethrough and intersecting the first face. The second mating waveguide connector comprises a second insert having a complementary mating portion. Such mating portion has a generally conical-shaped cavity therein truncated at a second face. The second insert further has a waveguide slot disposed therethrough and intersecting the second face. The second mating waveguide connector further comprises a second outer member rotatably mounted about the second insert.

Abstract: A carbon dioxide (CO.sub.2) waveguide laser is used to provide coherent infrared radiation. The mixture of gases in the laser includes helium, nitrogen, carbon dioxide, carbon monoxide, xenon and heavy hydrogen (deuterium). Carbon dioxide is the gain medium of the laser. During operation of the laser, a significant fraction of the CO.sub.2 dissociates to CO and O.sub.2. In the present invention, deuterium (D.sub.2) in the presence of excess CO catalyzes the recombination of CO and O.sub.2 back to CO.sub.2, thus yielding significantly increased power output from the laser. The presence of D.sub.2 also sustains a long sealed life from the CO.sub.2 laser at an enhanced power output level.

Abstract: A thermally conductive adhesive, and processes for formulating the same, are provided for bonding an electrical device package, such as an integrated circuit (IC) package, to a surface of a substrate, such as a printed circuit board. The thermally conductive adhesive comprises a polyurethane-based resin material and a predetermined amount of thermally conducting, electrically insulating material, such as alumina, mixed therewith. With such arrangement, a thermally conductive adhesive is provided having a low modulus of elasticity. Thus, such adhesive is soft and pliable rather than rigid, and thus deforms in response to the different amounts of thermal expansion, or contraction, of the IC package and PCB against, or away from, the thermally-conductive adhesive, thereby preventing damage to either the IC package or PCB, or separation of solder joints therebetween, due to such thermal expansion or contraction.

Abstract: A circuit for the suppression of spurious frequency components for use in cascaded class C common base transistor amplifiers. The circuit uses a capacitor and shunt diode connected in series between emitter and ground of each stage to slow the pulse falltime and thereby eliminate spurious frequencies resulting from parasitic-caused ringing. The cathode-to-capacitor junction is pulsed through an RF choke at the pulse repetition frequency by a pulse generator. This effectively replaces the fast trailing edge of the RF pulse with the slower turn-on time of the PIN diode circuit. The resulting slower falltime eliminates spurious frequency production that normally occurs at each stage of cascaded amplifiers.

Abstract: A low-profile patch radiator for use in an array antenna has a multilayer structure which includes a double-tuned impedance matching network and balun and a coaxial feed for linear polarization of the radiated waves. A second embodiment further includes a second double-tuned impedance matching network and balun and a second coaxial feed for dual polarization operation. The matching networks/baluns, which comprise microstrip circuits on Duroid substrates, increase the frequency bandwidth of the patch radiator.

Abstract: A laser radar system having amplification of the optical beam. In a system where it is desired to achieve greater information content or greater system sensitivity, one or more laser amplifiers in the beam paths provide greater optical power for increased distance. Eleven system architectures are disclosed for use with a modified Mach-Zehnder interferometer, eleven are disclosed for use with a Fizeau interferometer, and three are disclosed for use in a noncoherent optical system. The embodiments are distinguished by the number and placement of the laser amplifiers in the optical paths of the system.

Abstract: A laser is provided for generating a beam of continuous wave (CW) electromagnetic energy having a nominal frequency and amplitude. The frequency of the CW beam is modulated (FM) from the nominal frequency. The amplitude of the frequency modulated beam is modulated (AM) from the nominal amplitude to produce an amplitude and frequency modulated continuous wave (AM-FM CW) beam of energy. A local oscillator beam is produced from the frequency modulated CW beam. The AM-FM CW beam is directed for reflection by a target. The target-reflected return portions of the AM-FM CW beam are combined with the frequency modulated local oscillator beam to produce a beat frequency signal which is subsequently detected, the beat frequency signal having a frequency component representative of the range of the target. Such arrangement, when implemented in a radar system, provides such radar system with accurate target range measurements unambiguous over large ranges.

Abstract: A timing recovery apparatus for a burst mode communication receiver. The apparatus provides for optimum sampling and digitizing of received data at a plurality of data rates. In particular, a VCO is phase-locked to a local frequency reference prior to data being received. A reference timing preamble transmitted prior to the data is filtered and fed to the VCO causing it to injection lock such that the VCO becomes phase aligned with the preamble. The VCO is then permitted to "free run" during data transmission and continues to operate at substantially the same frequency. A synchronous divider and multiplexer, responsive to the VCO, allows selection of sampling clocks for the plurality of data rates. The divider is forced to a known state during VCO injection locking, to assure that the sampling clocks have maintained the proper phase for optimal sampling at the corresponding data rate. Further, means is provided to monitor the frequency of the VCO.

Abstract: A ring laser gyro uses a nonplanar equilateral (skew rhombus) ring path. In the preferred embodiment, the mirrors used to produce such path are mounted on a supporting cube having passages cut in the path of a beam of electromagnetic energy propagating therebetween. Preferably, the mirrors are positioned on the surface of the cube and produce a nonplanar equilateral ring path having path segments in two planes. In one embodiment, four mirrors are placed on the corners of the cube to define the vertices of a tetrahedron circumscribed by the cube. With such an arrangement, the sensitive axis is along one of the three mutually orthogonal principal axes of the cube. The tetrahedral ring is equiangular as well as equilateral; thus, all the incidence angles on the mirrors are the same.

Abstract: A ring laser gyro uses a nonplanar equilateral (skew rhombus) ring path. In the preferred embodiment, the mirrors used to produce such path are mounted on a supporting cube having passages cut in the path of a beam of electromagnetic energy propagating therebetween. Preferably, the mirrors are positioned on the surface of the cube and produce a nonplanar equilateral ring path having path segments in two planes. In one embodiment, four mirrors are placed on the corners of the cube to define the vertices of a tetrahedron circumscribed by the cube. With such an arrangement, the sensitive axis is along one of the three mutually orthogonal principal axes of the cube. The tetrahedral ring is equiangular as well as equilateral; thus, all the incidence angles on the mirrors are the same.

Abstract: An optical time delay unit for use in an optical phased array beam-steering system includes a switchable polarization rotator in conjunction with Brewster plates and mirrors to form electrically-selectable optical paths of different lengths. The switchable polarization rotator is aligned with the optical beam and is responsive to a control signal for varying the polarization of light passing therethrough. The Brewster plates receive the light passing through the first polarization rotator and are transmissive to a first polarization and reflective of a second. The transmissive and reflective paths are of different lengths, and are recombined at a second Brewster plate. The original polarization may be restored by a second polarization rotator. A plurality of time delay units may be cascaded to permit selection from among many paths of various lengths. In a preferred embodiment, the polarization rotators include liquid crystal cells having nematic phase molecules.

Abstract: A laser radar system wherein a beam of continuous wave (CW) electromagnetic energy is generated with frequency modulation (FM) and amplitude modulation (AM) being imposed thereon to produce an amplitude and frequency modulated, continuous wave beam of energy. The AM-FM CW beam is transmitted toward a selected target, portions of the transmitted beam being reflected by the target and received along with portions of the transmitted beam reflected by unselected targets and atmospheric clutter. A first signal is produced in response to the frequency modulation on the received beam portions reflected by the selected target, such first signal representing the approximate range of the selected target and substantially resolving the selected target from unselected targets and atmospheric clutter and having a relatively long ambiguous range interval.

Abstract: A receiver including two optimizers for demodulation, sampling and quantization of received QPSK digital data. One optimizer adjusts the phase of a reference signal used for demodulating the QPSK data into baseband in-phase and quadrature channels and another optimizer adjusts a sampling clock used to sample and quantize the baseband channels. The reference signal and the sampling clock are dithered in quadrature. Variations in the amplitude of the quantized data extracted by an eye quality monitor. Each optimizer multiplies the eye quality monitor output by a corresponding dither clock and integrates to form an error signal. Phase shifters, responsive to corresponding error signals and dithered clocks, adjust the phase of the demodulation reference signal and sampling clock. The data quality signal monitor translates the magnitude of the quantized data signals to a common set of signals for each state of the data signal.

Abstract: A high efficiency switching power supply includes a non-dissipative snubber circuit which provides dual polarity power utilized by a driver of the switching transistor. The snubber circuit, protecting the switching transistor in the supply and utilizing an inductor for storing energy normally dissipated as heat, charges filter capacitors with the stored energy to provide the dual polarity power sources. Zener diodes, paralelling the filter capacitors, regulate the power sources to provide output voltages sufficient for the driver to ensure saturation and cut-off of the switching transistor. The power sources allow the driver to directly drive the switching transistor for a high efficiency, small size, low cost and lightweight switching power supply.