Abstract: The efficiency of a metal silicide infrared (10) in greatly enhanced by depositing on the substrate (14) a stack (30) of alternating metal silicide (12,24) and silicon layers (22). The metal silicide layers (12,24) are connected to each other and to a contact pad (20) in the substrate (14) by a metal silicide deposit (32) on one side of the stack (30) and the silicon layers (22) are connected to each other and to the substrate (14) by a silicon deposit (34) on another side of the stack (30). The stacking of layers is made possible by depositing the silicon layers (22) at a rate of 1 .ANG./sec or less in a vacuum of 10.sup.-9 torr or better at a temperature of about 250.degree. C.

Abstract: A microstrip antenna including an orthogonal planar array (12) of patch radiators (10) with specially configured feed boards (16) provided for each column of array elements. Each such board includes a portion disposed parallel to the plane of the array and one or more portions bent or folded to extend in the direction of the array axis for a distance sufficient to accommodate necessary circuitry (36) and active devices (40). A metal supporting frame (18) serves both as a common ground for the assembly and as a heat sink for conducting some of the heat generated by the active devices mounted to the feed boards. An additional planar circuit board (22) is positioned beneath the supporting frame to accommodate the power combining circuit and to interconnect all of the elements. Connection between feed boards (16) and combiner board (22) is accomplished using via-connections or a coaxial cable network.

Abstract: An acoustic emission waveguide (10) for holding a test sample (29) in a hostile environment and guiding ultrasonic waves to a transducer (34) disposed in a non-hostile environment. The waveguide (10) includes a flattened test sample attachment end (15) having a flat bar clamp (22) to hold test specimens (29) thereto. The transducer attachment end (17) includes a clamp (32) which holds the transducer (34) firmly against the waveguide end (17) and against a threaded nut (30) which increases the surface area of the end (17) of the waveguide, such that enhanced acoustic transmission to the transducer (34) is achieved. A couplant grease is utilized in the test sample clamp (20) and in the transducer attachment clamp (32) to enhance the transmission of acoustic energy from the test sample (29) to the waveguide rod (12) and from the rod (12) to the transducer (34).

Abstract: One-dimensional sun sensing and angle measurement assemblies are deployed with substantially totally overlapping fields of view on a plane of a spacecraft body to protect sensors within a protected angular area of the plane, each of the analog sun sensors generating a signal indicative of incident sun along one axis and the presence of sunlight along an orthogonal axis thereto in the common plane. The sensors together generate an indication of the orientation of the sun relative to a target field of view which is a protected area. In an alternative embodiment, a digital sun sensor assembly is provided consisting of two or more independent digital channels and employing a slit aperture cooperating with a plurality of photocells laid out in a gray coded pattern. The digital device produces digital signals indicating relative position relative to axes in a plane.

Abstract: Process for increasing the density of an article. A coating containing boron nitride and carbon is applied to the article to form a coated article. The coated article is encapsulated. The encapsulated article is subjected to hot isostatic pressing. The coating reduces interaction between the article and the encapsulant during the hot isostatic pressing. The carbon is present in the coating in an amount up to about 30% by weight of the total boron nitride and carbon in said coating.

Abstract: A superior release coating for glass-encapsulated ceramic or ceramic composite bodies in hot isostatic pressing processes is obtained by mixing boron nitride with up to about 30% by weight of carbon.

Abstract: The angle of divergence of a laser beam (29) is controlled without significant variation of beam power by using a movable corner cube (18) to vary the length of the optical path of a noncollimated beam (12) so as to present a beam of varying diameter to a telescope lens (26). In a second aspect of the invention, the beam is made insensitive to vibration of the corner cube (18) by covering a portion of its beam-receiving face with a second reflector (32) which causes the beam to make a second pass through the corner cube (18) in a parallel but opposite direction therey cancelling any beam displacement caused by the vibration of the corner cube (18).

Abstract: A heater for a composite structure (2) is integrally formed as part of the structure (2) itself. The structure (2) comprises a layer of conductive fibers (30), such as a carbon felt mat, embedded in a nonconductive matrix (31). Electrodes (11, 12) inject an electrical current through multiple paths (15) through the conductive fibers (30), whereby the fibers (30) convert the electrical current to heat energy. Thus, the fibers (30) serve the dual roles of structural support to the composite structure (2) and heat converters. The composite structure (2) can be a portion of or an entire paraboloidal antenna reflector (6), in which case the heater of the present invention prevents and removes ice and snow build-up thereon. Cutting slits (8) into the composite structure (2) is a technique which can be used to vary the heat distribution within the structure (2). The slits (8) are positioned according to the shape of the structure (2) and the location of the current injecting electrodes (11, 12).

Abstract: The electronic simplicity of a rotating-telescope target acquisition device and the noise immunity and wide field of view of a non-rotating array device are combined in an assembly (10) using a rotating refractory telescope (21) on a gimbaled platform (28), and a combination reticle (38) and detector (34) on the same platform (28). The detector (34) is segmented (50) to detect the direction in which a target is substantially off the telescope's optical axis (32), and the detector (34) is also shielded (35) against any radiation coming from outside the optical path of the telescope (21). The reticle (38) also serves as the electrical connection (42,62) between the detector segments (40,50) and the contact pads (44,64) on the detector plate (36).

Abstract: The present invention is a control system for a seven-degree-of-freedom robotic arm. The robotic arm (10) includes two links (12 and 14), each having two degrees of freedom, and a spherical wrist (26) having three degrees of freedom. The kinematics of the spherical wrist are decoupled from the kinematics of the arm. The four degrees of freedom of the arm create a redundancy which provides versatility in the positioning of the arm. Fixing the redundant arm parameter and locating the end point (24) of the end effectuator path away from areas of limited mobility results in a marked simplification of the algorithms which describe the equations of motion of the arm. Additionally, further computation reduction can be achieved by updating the control gains less frequently than every microprocessor cycle, such as updating once for every five degrees of pitch angle rotation of either joint.

Abstract: The manufacture of monolithic HgCdTe detectors and Si circuitry in an IR focal plane array is achieved by forming a protective layer of SiO.sub.2 or SiN.sub.x on a silicon wafer containing silicon circuits, etching steep-wall recesses into the wafer, selectively depositing epitaxial single-crystal layers of GaAs, CdTe, and HgCdTe in the recesses fabricating HgCdTe IR arrays, and depositing appropriate insulating and conductive interconnection patterns to interconnect the Si devices with one another and the HgCdTe devices with the Si devices. Little or no GaAs, CdTe, and HgCdTe grows on the SiO.sub.2 or SiN.sub.x outside the recesses. Since material grown outside the recess is polycrystalline, it is easily chemomechanically removed.

Abstract: The encapsulation of ceramic preforms (10) for HIP processing is considerably simplified, and the use of standard laboratory glassware as encapsulation material is made possible, by placing non-sealed glass capsule parts (12, 14) around the preform (10) in the HIP pressure vessel (18), evacuating the vessel (18), heating the vessel (18) to a temperature at which the glass parts (12, 14) fuse together but do not collapse, and then pressurizing the vessel (18) and increasing the temperature therein as required for conventional HIP processing.

Abstract: A decoder for selected linear error correcting codes, such as a BCH code, uses relatively low-speed circuitry to determine syndromes and corresponding error locations for correcting the code. In a specific embodiment of a BCH linear cyclic invariant error correcting code, only cyclic invariants are stored in Read Only Memory such that the storage requirements of the Read Only Memory are minimized, and table look-up techniques are employed to speed apparent computation. In another specific embodiment of a linear error correcting codes, a Read Only Memory is used to store precomputed indicia of possible errors in the code word, and table look-up techniques are employed to determine one or more syndromes. The table look-up method avoids the complexity of error locating polynomials, algebraic root finders and real-time computation while reducing computation time.

Abstract: An antenna for transmitting and/or receiving circularly polarized (CP) electromagnetic radiation throughout a substantial portion of a sphere. A cylindrical waveguide (3,5) is associated with a transmit portion and a receive portion of the antenna, respectively. The outer surface of each waveguide (3,5) is covered with several conductive radiating patches (30,50) equidistant axially and circumferentially arranged. The patches (30,50) may be fed by elongated apertures (51,52) or by coaxial transmission line (41,42). In the former embodiment, CP is present within the waveguide (3,5), while in the latter embodiment, linear polarization is present within the coaxial transmission line (41,42). The individual patches (30,50) radiate CP in a direction normal to the patch (30,50) to produce CP in the broadside direction.

Abstract: A novel packaging system for VLSI circuits allows low-cost construction and maintenance of complex high density high-performance devices with low power requirements. The devices can be individually created by software means from a small selection of standardizable IC chips by disposing a plurality of chips in leadless chip carriers in a mosaic on a substrate, and configuring them by software to selectively communicate with other chips of the mosaic or even to individually change their operating function. The immediate juxtaposition of the chip carriers in the mosaic eliminates transmission line data skew, and also allows considerable savings in chip space and power requirements by dispensing with interconnection drivers, receivers and bonding pads.

Abstract: A heater for a composite structure (2) is integrally formed as part of the structure (2) itself. The structure (2) comprises a layer of conductive fibers (30), such as a carbon felt mat, embedded in a nonconductive matrix (31). Electrodes (11, 12) inject an electrical current through multiple paths (15) through the conductive fibers (30), whereby the fibers (30) convert the electrical current to heat energy. Thus, the fibers (30) serve the dual roles of structural support to the composite structure (2) and heat converters. The composite structure (2) can be a portion of or an entire paraboloidal antenna reflector (6), in which case the heater of the present invention prevents and removes ice and snow build-up thereon. Cutting slits (8) into the composite structure (2) is a technique which can be used to vary the heat distribution within the structure (2). The slits (8) are positioned according to the shape of the structure (2) and the location of the current injecting electrodes (11, 12).

Abstract: A piezoelectric motor actuated amplifier mechanism that utilizes a pair of saggital linkages having one relatively fixed saggital midpoint and joined at their end points to obtain a doubled amplification factor push stroke output from one relatively movable saggital midpoint. Thermal compensators are employed between the piezoelectric actuator and the saggital linkages to stabilize the amplifier throughout a wide range of temperatures.

Abstract: An efficient method for time-division multiplexing multiple digital signals into a single data stream for switching and/or transmission of information to a remote location. The apparatus according to the invention receives as input, to a multiplexer, a plurality of digital data streams of arbitrary word size and data rate, any one of the data rates being changeable with time such that the total data rate of all streams combined will, in general, greatly exceed the capacity of the multiplexer. Input digital signals are assumed to have an arbitrary word size and word rate subject to the constraint that the bit rate, that is, the word rate times the word size for each signal, is an integer multiple of a predetermined integer such that any time-varying mix of digital signals, regardless of word size, can be combined into a single time-division multiplexed bit stream in such a way that no individual signal, once placed in the format, will be moved to another place in the format.

Abstract: A novel packaging system for VLSI circuits allows low-cost construction and maintenance of complex high density high-performance devices with low power requirements. The devices can be individually created by software means from a small selection of standardizable IC chips by disposing a plurality of chips in leadless chip carriers in a mosaic on a substrate, and configuring them by software to selectively communicate with other chips of the mosaic or even to individually change their operating function. The immediate juxtaposition of the chip carriers in the mosaic eliminates transmission line data skew, and also allows considerable savings in chip space and power requirements by dispensing with interconnection drivers, receivers and bonding pads.

Abstract: A novel packaging system for VLSI circuits allows low-cost construction and maintenance of complex high density high-performance devices with low power requirements. The devices can be individually created by software means from a small selection of standardizable IC chips by disposing a plurality of chips in leadless chip carriers in a mosaic on a substrate, and configuring them by software to selectively communicate with other chips of the mosaic or even to individually change their operating function. The immediate juxtaposition of the chip carriers in the mosaic eliminates transmission line data skew, and also allows considerable savings in chip space and power requirements by dispensing with interconnection drivers, receivers and bonding pads.