Abstract: A modular jet spray device for use in cleaning submicron sized particles and molecular films using CO.sub.2 spray. The modular jet spray device comprises a valve body having first and second ends and an gas input for receiving a CO.sub.2 cleaning agent. A jet spray nozzle is removably secured to the first end of the valve body and comprises an input orifice and an output orifice. A sleeve assembly is removably secured to the second end of the valve body, and a needle assembly is removably secured to the sleeve assembly. The needle assembly has a needle that inserts into the input orifice of the nozzle. A micrometer is removably secured-to the sleeve assembly distal from the valve body and is coupled to the needle assembly for adjusting the position of the needle relative to the inlet orifice of the jet spray nozzle. A CO.sub.2 gas source is coupled to the gas input of the valve body. Optionally, a filter may be coupled between the CO.sub.2 gas source and the gas input of the valve body.

Abstract: An epitaxial structure and method of manufacture for a single heterojunction bipolar transistor capable of being utilized in high-speed and high-power applications. Preferably, the epitaxial structure comprises an N-type collector made from InP, a P-type base made from InP, and an N-type emitter made from a semiconductor material of approximately 39 mole percent AlP and approximately 61 mole percent Sb.

Abstract: A method for filtering actuator commands for a satellite control system to reduce resonant mode excitation despite uncertain knowledge of the resonance frequencies, due to parameter variations, nonlinearities, and the like. The present method filters the actuator commands with staggered proportional plus delay (posicast) filters having distinct delay values, chosen to provide a desired resonance attenuation over a resonance uncertainty range. The present method may be extended to filter multiple resonances by cascading the staggered filters for each resonance. The present invention has wide application, such as in spacecraft precession and translation maneuvers, as well as gimbaled payload stepping. A particular advantage of the present invention is its direct applicability to fixed-amplitude actuators (such as thrusters and stepper motors), and reduced excitation of resonances at frequencies above those of primary concern.

Abstract: A low-loss substrate system is provided for carrying and interconnecting optoelectronic/microwave circuits. The system includes a high-resistivity substrate, e.g., silicon of resistivity >1.times.10.sup.3 ohm-centimeter. A dielectric layer, e.g., silicon dioxide, is preferably deposited over at least a portion of the substrate. Low-loss microwave transmission members and passive microwave components, e.g., capacitors and spiral inductors, can be fabricated directly on the dielectric layer with thin-film techniques. Optoelectronic and microwave integrated circuits are preferably mounted on the substrate system with solder bumps and bonding pads. Other portions of the substrate can define grooves for receiving optical fibers. To enhance optical alignment, the grooves and bonding pads are preferably located with photolithographic techniques. The substrate system is especially suited for optoelectronic/microwave circuits that are realized with hybrid integration structures.

Abstract: An array (10) of diode lasers (12) is comprised of a substrate (22) having a plurality of electrically conductive surface areas (24, 24a, 24b, 24c) and a plurality of diode laser subassemblies (20) individual ones of which are conductively coupled to one of the plurality of surface areas (24a). Each of the diode laser subassemblies includes a diode laser (12), preferably a SE-DFB diode laser, that is conductively coupled to and mounted upon a first surface of an electrically conductive body or submount (14). The submount has a second opposite surface that is electrically coupled to and mounted upon one of the electrically conductive areas, preferably with a layer (25) of compliant, deformable material such as indium foil or an indium alloy. The individual diode lasers are preferably electrically connected in a series, voltage adding configuration.

Abstract: A slot radiator and a patch radiator are formed in a single antenna which is connected to a handheld, wireless telephone. The antenna can be pivoted to operational positions and excited to radiate linearly-polarized signals or circularly-polarized signals whose radiation patterns are respectively directed azimuthally and elevationally.

Abstract: A novel, inexpensive sensor (10) for detecting volatile hydrocarbons and other solvent vapors detects leaks in the fittings and valves of petroleum refineries and chemical manufacturing and processing plants. The sensor comprises (a) a dielectric substrate (12) having a major surface; (b) a pair of interdigitated, electrically conductive electrodes (14a, 14b) disposed on the major surface of the substrate; and (c) a composite coating (16) covering the interdigitated electrodes and comprising (1) a conductive polymer, and (2) a dielectric polymer with an affinity for the solvent vapors to be detected.

Abstract: A double heterojunction bipolar transistor (DHBT) is provided with a parabolic grade in bandgap at the base-collector junction. The parabolic grade in bandgap is close to parabolic in composition. The parabolic grade in bandgap is achieved by employing a chirped superlattice to mimic the parabolically varying alloy composition. Each period of the superlattice consists of one low-bandgap layer and one high-bandgap layer. The average composition in each period is determined by the relative thicknesses of these two layers. By varying the thickness ratio of these two layers approximately parabolically with (i) the distance from the base for a concave parabola and (ii) the distance from the collector for a convex parabola, the intended parabolic grade is achieved. The exact values may be computed numerically.

Abstract: High breakdown voltages for AlInAs layers in InP-based devices, such as a gate layer in an InP HEMT or a collector layer in a heterojunction bipolar transistor, are achieved by growing the AlInAs layer by MBE at a substrate temperature about 70.degree.-125.degree. C. below the temperature at which a 2.times.4 reflective high energy diffraction pattern is observed. This corresponds to a growth temperature range of about 415.degree.-470.degree. C. for a 540.degree. 2.times.4 reconstruction temperature. Preferred growth temperatures within these ranges are 80.degree. C. below the 2.times.4 reconstruction temperature, or about 460.degree. C. Higher breakdown voltages are obtained than when the AlInAs layer is grown at either higher or lower temperatures.

Abstract: A method for forming an index grating in an optical waveguide, such as an optical fiber, with precise control over the grating's period, cross-sectional shape and length. A single writing beam is passed through an optical grating mask, such as a phase mask. A photosensitive waveguide is spaced from the optical grating by a distance that corresponds to an integer fraction of the Talbot self-imaging distance, so that the optical grating (or a desired transformation of it) is imaged in the waveguide core. The grating image has substantially the same cross-sectional shape, period and length as the portion of the optical grating that is illuminated by the writing beam. Thus, an index grating that substantially replicates the cross-sectional shape, period and length of the optical grating mask, which preferably has a substantially square-wave shaped cross-section, is written in the waveguide core.

Abstract: A mounting and protective package for a monolithic microwave integrated circuit die (16) operable in the K.sub.a -band is formed of two high temperature co-fired ceramic layers sandwiched by two metal layers (10,12,20,26) that minimize hermetic sealing problems. The package has high frequency input/output lines (40,42), each including a section defining a microstrip line (40a,41a), a section defining a shielded strip line (40b,41b), and a section defining a capacitor (40c, 41c) . The capacitor is precisely defined to provide optimum input/output transmission line impedance that minimizes loss. The integrated circuit die (16) is mounted within a recess (14,46) in the package and is wire bonded (22,24) to input and output capacitors (40c,41c) that in turn are connected with shielded strip lines (40b,41b) and microstrip lines (40a,41a) for both input and output.

Abstract: A microbolometer detector element includes an optically absorptive material structure that absorbs a portion of incident radiation, and has a plurality of openings that diffract other portions of the incident radiation. The absorptive structure has an electrical resistivity that varies as a function of its temperature. An optical radiation director re-directs the diffracted optical radiation back to the absorptive structure. The distance between the radiation director and the absorptive structure is tuned so that, for a predetermined design wavelength, optical radiation that is re-directed back to the absorptive structure constructively interferes with incident optical radiation that is not reflected by the absorptive structure. The constructive interference causes the absorptive structure to absorb substantially more optical radiation at the design wavelength than at other wavelengths.

Abstract: A ceramic member (52) is direct-bonded to a copper composite substrate by heating to diffuse copper to the surface of the copper composite substrate (56), oxidizing the copper composite substrate following heating, placing a ceramic member in contact with the resulting oxidized substrate, and forming a copper-copper oxide eutectic (54) at the interface between the copper composite substrate and the ceramic member by heating. The eutectic, upon cooling, forms a bond between the copper composite and the ceramic.

Abstract: A spacecraft multilayer insulation blanket is made from multiple sheets of polyimide e.g. KAPTON. A preferred six sheet embodiment employs three carbon loaded sheets (26, 32, 34) separated by two dielectric sheets (28, 30). A third dielectric sheet (36) insulates the carbon loaded sheets from the spacecraft body. The outermost carbon loaded sheet (32) has a high resistivity and is primarily transmissive while the other two carbon loaded sheets (26, 34) have a low resistivity and are primarily reflective.

Abstract: A 3-D integrated circuit (IC) chip stack employs a plurality of discrete chip carriers that are formed from dielectric tape layers such as fused low temperature cofired ceramic (LTCC) tape. The chips are lodged in cavities within the tape layers, and are either flip-chip or wire bond connected to electrical routings that extend along one or more tape layers toward the periphery of the carrier. Intercarrier interconnects are provided between the routings for adjacent carriers, either through the carrier side walls or externally. The carriers are mechanically secured to each other within the stack either by connectors that also provide an I/O signal capability, or by an adhesive if external electrical connectors are used. The structure is strong, compact, inexpensive, compatible with conventional IC chips and capable of disassembly and reassembly to replace a bad chip.

Abstract: A passively controlled multiple output fiber laser system in which the frequency relationships between all of the optical outputs remain constant over time includes a plurality of fiber lasers for generating respective output beams. The lasers are positioned in close proximity to each other so that they experience the same environmental conditions. Each laser includes at least one Bragg reflection grating that controls the frequency and bandwidth of the laser's output beam. The Bragg gratings are formed so that they respond equally to environmental changes. In a preferred embodiment, the fiber lasers are made from a plurality of substantially identical photosensitive fibers, and Bragg gratings are exposed simultaneously under identical exposure conditions in each of the fibers. A multiple output fiber laser system suitable for heterodyne LADAR systems is also provided.

Abstract: An improved electro-optic modulator having reduced amplitude of acoustic resonances is provided. Acoustic energy is efficiently removed from the electro-optic crystal and channeled into electrode and side dielectric bars where it is dissipated by materials acoustically matched to the electro-optic crystal, that is, materials that have acoustic impedances within .+-.15% of that of the electro-optic material.

Abstract: A hermetically sealed electromagnetic window is formed by butt end brazing an overhanging dielectric window between first and second waveguide segments. The waveguide segments have opposed knife edges with a dielectric insert positioned between the knife edges. A pair of brazing forms are inserted between the insert and the two knife edges. The window is heated, causing the brazing material to reflow and provide a hermetic seal between the insert and the waveguide segments, and a conductive path between the waveguide segments.

Abstract: A diamond lattice structure is employed as a ground plane in an array antenna system. The ground plane structure reflects incident energy radiated by the antenna radiating elements. The structure is fabricated from a layer of dielectric photonic band gap material in which a periodic void structure is defined. The void diameter is selected to maximize the void volume within the structure. Methods of constructing the ground plane are described.

Abstract: A dynamic balance mechanism for balance control of a gyro stabilized (spinning) satellite is disclosed. An elongated gear rack is attached to the spacecraft. A movable mass is mounted by guide rollers on the gear rack and translates along the gear rack according to requisite electronic commands. The movable mass includes a housing, a stepper motor, a rotary potentiometer, a cable reel, a pair of gear heads and a pinion gear. The pinion gear meshes with the rack and is driven by the stepper motor. The potentiometer measures the position of the movable mass on the gear rack. The cable reel saves space and minimizes harness jamming conditions. The invention secures better weight efficiency.