Abstract: A method of maintaining a laser weapon target aim point. The method includes the step of selecting an aimpoint (42) on a target (24). The target is then engaged with a laser beam (23). The tracker (36) then receives target scene information, and detects both a target image and a target laser hit spot (40). The tracker (36) then determines the vector distance between the target aimpoint and the target laser hit spot, and drives the vector distance (70) to zero to close the loop between the target aimpoint and the target laser hit spot location. The method and system of the present invention thereby increase the probability of a target kill by enabling the tracking system to maintain a laser lock on the target aimpoint from an initial target engagement to a target kill stage.

Abstract: A low vibroacoustic structure 10 according to the present invention comprises a first facesheet 12 defining a plurality of first holes 22, a second facesheet 16 defining a plurality of second holes 36, and a core 14. The first and second facesheets are attached to opposed surfaces of the core. The core defines a plurality of passages 32 in communication with the first and second holes to form channels 38 through the structure. The core is typically a honeycomb sheet. The first and second facesheets and the core are formed of lightweight materials such as lightweight metals, metal matrix composites, or polymer matrix composites. The perforated structure reduces structural acoustic coupling and acoustically induced vibration. The structure can be formed as a panel. The panel can be attached to support structures exposed to high-energy acoustic environments to reduce acoustically induced vibration of the structures.

Abstract: A waveguide-to-microstrip transition package (30) for processing electromagnetic wave signals includes a waveguide (32) for directing the signals to the input of the waveguide (32). A substrate (34) overlaps the input of the waveguide (32) to form a hermetic seal. A metallized probe (36) conducts the signals to a microstrip line (40) and is patterned upon the substrate (34). The transition (30) also includes an iris (48) formed from a metallized pattern on the opposite side of the substrate (34) from the probe (36). The special design of the probe (36), the structure of the iris (48) and the wave guide cavity (46) above the probe (36) allow impedance matching and efficient signal transfer from waveguide (32) to microstrip line (40) or from microstrip line (40) to waveguide (32).

Abstract: A method of fabricating a low-inductance, in-line resistor includes the steps of: depositing a superconductive layer 12 on a base layer 14; patterning an interconnect region 16 on the superconductive layer 12; and converting the interconnect region 16 of the superconductive layer 12 to a resistor material region 18. The resistor region 18 and the superconductive layer 12 are substantially in the same plane. The method can further include the steps of depositing a conductive layer 22 on the resistor region 18 and on the photo-resist layer 20, and lifting off the photo-resist layer 20 to leave the conductive layer 22 on the resistor region 18. As such, the conductive layer 22 provides a low sheet resistivity for the resistor region 18.

Abstract: An optical wavefront sensor for measuring phase tilt in two dimensions across the cross section of a beam (14), using only a single lenslet array (26) and a single camera sensor array (28). The rectangular lenslet array (26) is oriented at 45 degrees to first and second orthogonal sets of axes defining multiple points of interest (22') in the beam cross section, such that each lenslet subaperture is centered (at 40) between adjacent points of interest on the first and second axes. The points of interest (22') are locations corresponding to the positions of actuators (22) in an adaptive optics system. The camera sensor array (28) has more cells per unit area than there are subapertures per unit area. Only selected cells are activated, to provide for measurements at the approximate mid-points of lines between adjacent points of interest (22') on the first and second orthogonal axes.

Abstract: A bandwidth compensated switched bridged-tee attenuator having an attenuation state and a reference state. In order to cause the overall bit attenuation .DELTA.A to be frequency independent over a relatively wide range of frequencies, one or more additional switches are provided to cause the attenuation state to essentially track the frequency dependence of the reference state. Since the overall attenuation .DELTA.A is the difference between the attenuation in the attenuation state and the attenuation in the reference state, the overall attenuation .DELTA.A, is virtually frequency independent over a relatively wide range of frequencies.

Abstract: A method and apparatus are provided, for maintaining synchronous return and forward communications links between user terminals and earth stations communicating via a common satellite in a satellite based telecommunications system. Each user terminal maintains a closed synchronization loop with its associated earth station based on timing and frequency error offset signals received by the user terminals. The user terminals update their internal timing and frequency generators based on the received error offset signals. In an earth station sharing embodiment, one of the earth stations is designated as a master earth station while the remaining stations are designated as slave earth stations with respect to a common satellite. The slave earth stations monitor a return link between at least one user terminal and the master earth station.

Abstract: A multiple altitude satellite relay system is disclosed in which Medium Earth Orbit satellites are continuously linked with at least one Geosynchronous satellite to provide uninterrupted relaying of messages and data. The Medium Earth Orbit satellites are synchronized with the Geosynchronous satellites to produce continuous links. A parameter to achieve the synchronization involves the positions of the Medium Earth Orbit satellite relays relative to the positions of the Geosynchronous satellite relays. Another parameter to achieve synchronization involves the ratio between the orbital periods of the Geosynchronous satellite relays relative to the orbital periods of the Medium Earth Orbit satellite relays. These parameters may be further adjusted to provide continuous links above the horizon of the earth.

Abstract: A lanthanum aluminate (LaAlO.sub.3) substrate on which thin films of layered perovskite copper oxide superconductors are formed. Lanthanum aluminate, with a pseudo-cubic perovskite crystal structure, has a crystal structure and lattice constant that closely match the crystal structures and lattice constants of the layered perovskite superconductors. Therefore, it promotes epitaxial film growth of the superconductors, with the crystals being oriented in the proper direction for good superconductive electrical properties, such as a high critical current density. In addition, LaAlO.sub.3 has good high frequency properties, such as a low loss tangent and low dielectric constant at superconductive temperatures. Finally, lanthanum aluminate does not significantly interact with the superconductors. Lanthanum aluminate can also used to form thin insulating films between the superconductor layers, which allows for the fabrication of a wide variety of superconductor circuit elements.

Abstract: A technique for reducing the acoustic response of a spacecraft electronics equipment module that is structurally and 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 adjusted in stiffness to reduce its dynamic vibration response to acoustics and launch transients. These adjustments are facilitated by the external mounting of the panel to the core structure, preferably using a statically determinate mount that renders the module even less susceptible to vibration transferred from the core structure. External mounting removes the panel from the primary structure load path, which provides the freedom to adjust the stiffness as desired.

Abstract: Both recursive and non-recursive fiber-optic loop elements are cascaded to form various fiber-optic lattice configurations to form a fiber-optic signal processor for use in wideband applications capable of processing radio frequency (RF) signals. Each fiber-optic loop element includes a fiber-optic element, such as a monomode optical fiber or a monomode optical waveguide formed in a loop by way of a fiber-optic coupling device and one or more reflection mechanisms, such as a Bragg grating. In order to provide increased flexibility, the present invention allows the reflectivities of the reflection elements to be selected to provide additional flexibility in creating the frequency response characteristics of an optical signal processor.

Abstract: A method and an apparatus are provided for transmission of band limited QPSK data which is orthogonal direct-sequence spread using a BPSK sequence which preserves the band limiting even with subsequent amplification by non-linear amplifiers. This feature allows inexpensive implementation in mass produced, portable communications devices.

Abstract: A system and method are set forth for photoacoustical analysis of isotope and other compounds having telltale absorption wavelengths between 1700-2500 nm. The system and method includes a Co:Mg F.sub.2, optical parametric oscillator (OPO) or diode laser tunable between 1700-2500 nm which is directed into a sample at energies sufficient to generate detectable acoustical emissions. A microphone detects the emissions for processing and analysis. The system and method is adapted to detect stable isotope compounds such as .sup.13 CO.sub.2 as well as other chemical compounds. For non-gaseous compounds, a CO.sub.2 or diode laser is used to photoablate the gaseous sample contacting the suspected compound.

Abstract: An optical amplifier for a high power, solid state laser which includes a slab of a solid state laser material, for example, yttrium-aluminum-garnet (YAG) crystal. One or more diode arrays may be vertically stacked and configured to provide generally uniform energy distribution in the crystal in a vertical direction. By maintaining a relatively uniform energy distribution in the crystal in a vertical direction, thermal and stress aberrations of the resulting laser beam are minimized.

Abstract: An image tracker (10) that tracks an object (16) targeted for engagement by a laser weapon (12). The tracker (10) includes receiver optics (31) that receive radiation (30) from both a detected target (16) and a laser beam (14) incident thereon, and a polarizing beam splitter (44) that splits the radiation into a first beam of reflected laser radiation (46) and a second beam of detected target radiation (47). The polarizing beam splitter (44) reflects the first beam of reflected laser radiation (46) in a first direction for imaging purposes and linearly polarizes the second beam of detected target radiation (47). A beam polarizer (60) circularly polarizes the second beam of detected target radiation. A micromirror array (66) reflects the circularly polarized detected target radiation back through the beam polarizer (60) to linearly polarize the second beam of detected target radiation (47).

Abstract: A spacecraft electronics equipment module that is structurally and 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 using a statically determinate mount that renders the module structurally and thermally independent of the core structure. A combination of mounting brackets and struts secures the module from translational movement in all three axes, but permits thermal expansion and contraction in the plane of the panel without transferring any thermally induced forces to the core structure. A radiation shield secured over the electronics components also serves to further stiffen the panel and to enhance thermal conduction into the panel, which can radiate heat from both faces. Heat pipes can be attached to the panel to further enhance distribution of heat across the panel.

Abstract: A high-temperature (10K) superconductive integrated circuit has a ground plane (2), an interlevel dielectric (6), and a low value resistor (18) to provide conductive paths to reduce parasitic circuit inductances, thereby increasing the speed and performance of the integrated circuit. The circuit also includes a high value resistor (20) connected between interconnect wires (34) to produce a desired resistance with a short distance between the interconnect wires (34), thereby significantly reducing the circuit area.

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 scrapper mirror (32) disposed downstream of the laser (12) for receiving the beam (18) and an optical fiber (48) disposed adjacent an edge (84) of the mirror (32) for receiving a high fringe frequency interferrogram (86) formed by the mirror (32). The mirror (32) is coupled to a rotation stage (14) for rotating the mirror (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 system and method for frequency dehopping of spread spectrum communication signals includes a downconverter having two mixer stages, each mixer stage providing coarse frequency dehopping. The local oscillator injection frequency of each mixer stage is selectable by way of a plurality of relatively easily generated tones. The output of the second mixer stage is sampled by an analog-to-digital converter to enable fine tuning dehopping to be performed in the digital domain and subsequently demodulated in a demodulator circuit.

Abstract: Both recursive and non-recursive fiber-optic loop elements are cascaded to form various fiber-optic lattice configurations to form a fiber-optic signal processor for use in wideband applications capable of processing radio frequency (RF) signals. Each fiber-optic loop element includes a fiber-optic element, such as a monomode optical fiber or a monomode optical waveguide formed in a loop by way of a fiber-optic coupling device and one or more reflection mechanisms, such as a Bragg grating. In order to provide increased flexibility, the present invention allows the reflectivities of the reflection elements to be selected to provide additional flexibility in creating the frequency response characteristics of an optical signal processor.