Abstract: An aircraft antenna system integrated into one or more walls of an equipment pod (12) mounted beneath an aircraft (10). The equipment pod (12) has at least one wall with an antenna notch built into it. The antenna notch is tapered or flared toward a wider opening and is bounded on each side by conductive portions of the same pod wall. Other walls of the pod (12) are made from conductive materials, which are in electrical contact with the aircraft structure. The equipment pod (12) provide multiple antenna structures for use in a variety of aircraft applications. Further, use of multiple pods (12) allows an aircraft to be more easily reconfigured for different missions by removing and replacing the equipment pod.

Abstract: An optical amplifier which includes an elongated slab of solid state lasing material, such as a rare earth doped yttrium-aluminum-garnet (YAG). In order to provide a relatively increased absorption length and thus a higher overall efficiency, the optical amplifier in accordance with the present invention incorporates end pumping in which the pumped light is coaligned with the amplified light resulting in relatively longer absorption lengths and higher overall efficiencies. The coaligned pumped sources are directed to lateral faces of the slab which include windows, formed from an insulating coating such as an anti-reflection coating, at the pump wavelength. In order to cause internal reflection of the pump beam along the lasing axis, the end faces are formed at about a 45.degree. angle relative to the longitudinal axis which causes the pumped light to be reflected within the slab co-axially with a amplified light.

Abstract: A dc distributed Gm gain control circuit formed from differential bipolar distributed amplifier topology. In accordance with an important aspect of the invention, the distributed Gm gain control relies on a shunt configured, area weighted, transistor current source switches (QA.sub.x, QB.sub.x, QC.sub.x, QD.sub.x) for each differential amplifier stage (22, 24, 26, 28) of the distributed amplifier (20) in order to control the offset voltages of each differential amplifier stage (22, 24, 26, 28) without imposing performance degradation by way of a series resistive ladder.

Abstract: A channelizer for signals for optically channelizing RF signals modulated onto an optical carrier by optically separating the RF signals and mapping the RF signals by way of an optically dispersive element, such as a diffraction grating. In an alternate embodiment of the invention, two stages of optical filters elements are provided in series to perform sequential channelization. Bragg reflection gratings are used for coarse filtering into predetermined bands while Fabry-Perot filters tuned to specific sub-bands of the Bragg reflection gratings are used for channelization. In alternate embodiments of the invention, a silica planar waveguide and an optical splitting device, such as a Talbot splitter, are used.

Abstract: The present invention provides a computer controlled apparatus and method for producing high quality fiber optic Bragg gratings. According to the invention, the apparatus (10) preferably includes a laser (12) for generating an ultraviolet beam (18), a rotatable prism (32) disposed downstream of the laser (12) for receiving the beam (18) and an optical fiber (48) disposed adjacent a bottom edge (84) of the prism (32) for receiving a high fringe frequency interferrogram (86) formed by the prism (32). The prism (32) is coupled to a rotation stage (14) for rotating the prism (32) about a pre-selected pivot point (36) relative to the angle of incidence of the beam (18) to vary the Bragg wavelength at the fiber core.

Abstract: A reworkable multi-chip module contains a large multi-chip module package (2) with an opening at the top to permit access to an internal region for semiconductor devices, the opening being at least four square inches area with the length or width dimension being at least two inches. The opening is sealed with a stiff closure (1) of sufficient rigidity to withstand at least one atmosphere of differential pressure without significant deflection, is removable in a single piece and may be reinstalled. The closure includes a panel of electrically non-conductive material (3) and a metal flange (5) borders the periphery of the panel to support the panel on the top of the module package.

Abstract: A communications system (100) is disclosed for processing at least one uplink channel contained in at least one uplink beam (112) transmitted to a satellite (106). The communications system (100) includes at least one user terminal (110) that extracts a system clock, a synchronization word, and timing correction information from a downlink beam transmitted by a satellite. The user terminal includes a timing controller (226) that aligns uplink channel transmissions by generating a system clock based on the downlink symbol clock, said synchronization word, and said timing correction information. The user terminal includes at least one spread-spectrum spreader (254) for encoding at least one uplink channel, and a transmitter connected to the spread-spectrum spreader (254) for transmitting said at least one uplink channel in an uplink beam (112).

Abstract: A laser controller (12) that has particular application for controlling a solid state diode laser (10) including a series of gain modules and associated diode arrays. The laser controller (12) includes a control console (44) including a touch screen (46) that allows a laser operator to interface with the controller (12) to control the laser (10) and laser parameters. The control console (44) includes a target monitor (50) that allows the operator to view the laser beam at a reduced beam intensity for alignment and beam quality purposes. The laser controller (12) further includes a computer (14) having a counter circuit (20) that outputs a signal to set the pulse width and pulse rate of the laser beam output. This control allows the laser beam output to be ramped from one beam intensity to another beam intensity during a laser operation.

Abstract: An electroabsorptive modulator (EAM) for providing RF modulation of optical inputs signals. The EAM is formed as a semiconductor waveguide on a semiconductor substrate with an optical input port and an optical output port and electrical contacts for connection to the RF input. The configuration of the waveguide portion of the EAM is optimized to provide a modal match with the particular optical device to which the EAM is to be connected, for example, an optical fiber. By optimizing the modal match between the EAM and the optical device to which the EAM is connected, the optical insertion losses are minimized thereby improving the overall performance of the optical system. The device is formed from a plurality of quantum wells selected to compensate for the increased mode field dimensions.

Abstract: A digital audio radio system where multiple digital data versions of a single source signal are transmitted to one or more satellites to be rebroadcast to a defined reception area where the multiple versions are delayed with respect to each other. One of the signals is intended to be used by a mobile receiver if the transmission from the satellite is not blocked, and the other one or more versions are intended to be used if the broadcast signal from the satellites is blocked. Because the multiple versions represent the same source signal that is received at different times, if the signal from satellites is blocked, the signal being received at a different time can be used. The signals that are to be used when the broadcast signal is blocked can be of a lesser data quality to conserve system resources.

Abstract: The present invention relates to a high resolution positioner that may be used to measure the lateral displacement between one object, such as a beam compactor, relative to another object, such as a rear cone, which are separated over a moderate distance. The positioner includes a relatively small laser mounted on one of the objects, such as the beam compactor, which is dithered in orthogonal directions creating a Lissajous pattern. The Lissajous pattern is detected by a pinhole detector on a separate object, such as a rear cone. With such a system, displacement of one object, such as a rear cone bench, relative to another object, such as a beam compactor bench, can be relatively accurately determined and used to develop an error signal providing closed loop alignment of the two objects relative to each other.

Abstract: A method for reducing interference and increasing spectral efficiency in a frequency reuse pattern (600) is disclosed. The method includes the steps of generating n original communications beams (302-308) assigned to substantially non-overlapping frequency bands, with the original communications beams extending over a first set of predetermined bandwidths. The method also generates n shifted communications beams (402-408) shifted by an orthogonal frequency separation from the n original communications beams (302-308), with the n shifted communications beams (402-408) extending over a second set of predetermined bandwidths. The method projects the n original communications beams (302-308) and the n shifted communications beams (402-408) in a frequency reuse pattern (600) over a region of interest by alternating the n original communications beams (302-308) with the n shifted communications beams (402-408).

Abstract: A method and apparatus for adjusting the location of the back focus of a lens while maintaining the primary focal point location thus eliminating the need to position external components around the back focus location. Instead, the back focus can be positioned around the external components. The shape of the first and second surfaces of the lens are altered to adjust the back focus to a desired location while maintaining the location of the primary focus.

Abstract: An apparatus (1) is provided for treating a target area (22) of a tooth (10). The apparatus (1) generally comprises a coolant delivery system (20) and an ultraviolet laser system (15). The coolant delivery system (20) delivers coolant (52) to the target area (22) while a light guide (44) focuses ultraviolet radiation thereon. The ultraviolet radiation (18) and coolant (52) combine to ablate a desired material without generating excess heat which may otherwise char surface tissue or cause thermal damage.

Abstract: A vibration control system is provided for an appendage such as an antenna 10 coupled to a platform such as a spacecraft 12. The antenna 10 is coupled at a base 14 so as to extend from the spacecraft 12. A plurality of guidelines 20 extend between remote portions 22 of the antenna 10 and the antenna base 14. A plurality of motion control elements 36 are provided within the antenna structure for reducing oscillation settling time of the antenna 10 relative to the spacecraft 12. The motion control elements 36 include a material disposed therein having its damping response changed according to the magnitude of an electric or magnetic field applied thereto.

Abstract: A spacecraft electronics equipment module that is thermally independent of a core spacecraft structure to which it can be mounted. The module takes the form of a thermal radiation panel on which electronic components are directly mounted. The panel is attachable to the core structure and includes its own double-sided radiator for cooling of the electronics components, an integral heater for raising the temperature is needed, a thermal controller, for automatically regulating the temperature of the module components, and heatpipes for distributing the heat more uniformly across the radiating surfaces.

Abstract: A hyperspectral detection and seeking system for use in air-to-air, air-to-ground and ground-to-air missiles. The hyperspectral detection and seeking system includes a hyperspectral imaging system and a tracking system. Hyperspectral signatures for targets of interest may be either observed directly prior to launch or preloaded into the detection and seeking system. A tracking system provides for tracking of a target matching the preloaded or hyperspectral signature observed prior to launch. The hyperspectral detection and seeking system thus provides relatively higher precision for detecting and seeking targets with hyperspectral signatures. Since such hyperspectral signatures are formed from literally hundreds of spectra, the system is virtually immune to countermeasure since any countermeasures would effectively have to match its own hyperspectral signature over a relatively wide spectral range.

Abstract: The laser beam produced by the improved precision laser maintains an axial stability of less than 20 micro-radians in the presence of ambient temperature changes and shock and vibration of as much as 100 g's, achieving a new milestone in stability. In the new laser one end of the resonator (7) is hard mounted to the laser bench (13) and the other end of the resonator is mounted to that laser bench by a flexure (17). The flexure is designed to resiliently yield in the presence of thermally induced strain on the bench while retaining sufficient stiffness against foreseeable shock and vibration.

Abstract: A chemical sensor for detecting a chemical species in a gas comprises a detector element including a porous organic semiconductor comprised of a material on which the chemical species in the gas is adsorbed. The chemical sensor further comprises a power source for producing a bias voltage and a depletion region in the detector element. The chemical species percolates through the organic semiconductor and into the depletion region under the bias voltage, causing a change in the capacitance of the detector element. A light source irradiates the gas with light before entering the detector element. The light changes the chemical properties of the chemical species and enhances the adsorption selectivity of the organic semiconductor. The chemical sensor can determine both the presence and concentration of the chemical species in the gas based on the change in capacitance in the detector element. The chemical sensor can be provided in a portable unit suitable for field testing applications.

Abstract: A superconducting cell (10) is provided which has a storage loop (12), a read-out loop (14), and a direct coupling element between the storage loop (12) and read-out loop (14). The direct coupling element is preferably an inductor (30) common to the storage loop (12) and read-out loop (14). The superconducting cell (10) is preferably a vortex-transitional superconducting memory cell. In the superconducting cell (10) a first address line (18) is directly connected to the storage loop (12) and a second address line (16) is electromagnetically coupled to the storage loop (12). The storage loop (12) has a first switchable storage element (20) to switch the superconducting cell (10) into the storing state, when currents on the first and second address lines (18), (16) have the same polarity, and into the reading state, when currents on the first and second address lines (18), (16) have different polarity.