Abstract: Wavelength conversion apparatus is described that utilizes a Kerr cell to modulate the polarization of a pump laser beam having a first wavelength before the beam is input to an optical parametric oscillator/amplifier wavelength converter to generate a laser beam having a second wavelength. By modulating the polarization of the pump laser beam using the Kerr cell, the optical wavelength converter can be controlled to switch on and off or otherwise amplitude modulate the second wavelength laser beam output from the converter, and to correspondingly amplitude modulate the first wavelength and all other laser beams being output from the converter. In addition, with the pump laser beam and the second wavelength laser beam always being output from said wavelength converter there is a substantially constant thermal load on said wavelength converter creating substantially constant thermal lensing in the wavelength converter crystal that may be easily compensated using optical means.

Abstract: A method for deflecting a projectile from an initial trajectory. Such a projectile has a first surface area and a second surface area and moves through a gaseous atmosphere with a surrounding plasma sheath. This method includes the step of directing electromagnetic radiation toward the projectile, wherein the electromagnetic radiation has a wavelength which is absorbed by the plasma sheath but is not substantially absorbed by the gaseous atmosphere.

Abstract: An optical system with improved boresight stability having optical elements and a beam expander oriented on a chassis, wherein the beam expander is mounted for minimal movement. By minimizing movement of the beam expander, the angular error of a laser beam travelling through the optical system and subject to various angular tilt errors is reduced by an amount inversely proportional to the magnification ratio of the beam expander based on optical principles. In one embodiment the beam expander is mounted on a highly stiff location on the chassis and away from thermal stresses. Another embodiment is to mount the beam expander to a structural support of a higher assembly. The present invention isolates the beam expander from the instability of individual optical elements and from deformation of the optical bench that impairs the performance and diminishes benefits otherwise gained from the optical principles.

Abstract: A decoy deployment and retrieval system includes an extensible boom and corresponding cradle or saddle for use in the retrieval of the towed decoy such that, upon retrieval, the extensible boom with its decoy captured in the cradle is retracted into a chamber so that the decoy can be deployed over and over again. In one embodiment, the decoy is both towed by, and controlled over, a fiber optic line in which a load cell is used to detect tension on the line to prevent damage, and a fiber optic rotary joint is utilized along with high voltage slip rings to permit electrical and optical coupling without backlash, fouling or damage to the line.

Abstract: An apparatus for reducing switching regulator noise from outputs of multiple switching regulators is disclosed. The apparatus includes an operational amplifier, an capacitor, a resistor and a pair of diodes. The switching regulators are connected in series to provide a positive output rail and a negative output rail. The output of the operational amplifier in connected to an inverting input of the operational amplifier and a positive sensing input of one of the switching regulators. The non-inverting input of the operation amplifier is connected to the positive output rail of one of the switching regulator via the capacitor. The resistor is connected between a positive voltage output of one of the switching regulators and the capacitors. The pair of diodes is connected between the positive voltage output of one of the switching regulators and the negative output rail of the switching regulators.

Abstract: An acoustic transducer design having a slotted oval-shaped shell and active transducer elements located on the inner surface of the shell is disclosed. The design provides a high power, ultra-low frequency oval projector having a number of applications, including underwater seismic prospecting and fish mitigation.

Abstract: An integrated piezoelectric ultrasound array structure configured to minimize the effects of differential thermal expansion between the array and the integrated circuit and to improve the mechanical and acoustical integrity of the array. The transducer array may have an interposed thinned supporting substrate and is matched to the integrated circuit substrate for thermal expansion so as to retain mechanical integrity of the array/IC bond within the working temperature range. Transducer elements are laterally isolated acoustically and as to thermal expansion by air or other acoustically attenuating medium of lower elastic modulus material between the elements. Acoustical effects are vertically acoustically isolated with capacitive coupling and small area solder bumps relative to wavelength, and further laterally acoustically isolated by thin supporting substrates relative to wavelength, including thinned semiconductor integrated circuit substrates.

Abstract: A ballistics fire control system for a spin or fin stabilized projectile is provided with means which are operated such that the closest point of approach between a fired projectile and a target is taken to be at the instant the projectile velocity vector (6) is orthogonal to the position error vector (13) between the projectile and target in accordance with the relationship: Vp•(PP−PF)=0 where Vp is the projectile velocity vector, PP is the projectile trajectory or position vector, PF is the target future position vector, • is the vector dot product and (PP−PF) is the position error vector.

Abstract: A method is disclosed herein for evaluating quality of an image. The disclosed method contemplates receiving a spectral image and extracting a plurality of pixels therefrom. The plurality of pixels are converted into a plurality of spectral vectors, wherein each element in each spectral vector represents a property of a respective one of N spectral bands. The plurality of spectral vectors are then categorized into a set of M classes. The method further includes the step of computing a mean vector for each of the M classes based upon the spectral vectors associated therewith. Next, spectral similarity values between pairs of the mean vectors are computed. The distribution of these spectral similarity values may then be analyzed in order to obtain information relevant to image quality.

Abstract: Techniques enabling electronic control of propagation constant associated with meanderline loaded antennas and phased arrays are disclosed. An activation layer can be electronically stimulated to change its characteristics (e.g., capacitance or shape) so as to enable the control independent of antenna operating frequency.

Abstract: A rotating machine including a rotating shaft: a plurality of conductive rotor bars spaced from the rotating shaft and fixed to the rotating shaft through at least one intermediate member, where at least one of the plurality of conductive rotor bars have at least one first internal conduit; and a circulator for establishing a coolant circulation through the first internal conduit.

Abstract: Optical bench mounting and thermal management techniques are disclosed that enable increased dimensional stability. Output power, beam divergence, and boresight stability of the laser are thus maintained. A separate optical bench is pseudo semi-kinematically mounted to a chassis. A number of heat dissipation or heat management techniques can be utilized for heat generating components on the bench. For example, hot components (e.g., laser crystals) can be mounted on a cryo-cooler or other heat-pump, or attached to the chassis instead of the bench. Thermal loads can be balanced across the thickness of the bench to minimize bowing of the bench, and thermal strapping can be used to conduct heat away from hot components mounted on the bench to other locations (e.g., chassis or elsewhere) where the heat can be more efficiently handled. Thermal insulators and thermal damming can be used to inhibit heat flow from components into specific bench locations.

Abstract: Body-worn antennas operate in combination with a direction finding processor to be able to detect the presence of electromagnetic radiation involved in communication as well as the direction of the source of the electromagnetic radiation. In one embodiment, a number of wide bandwidth antennas, 2 MHz to 40 GHz, are incorporated into a body-worn vest or garment such that an individual wearing the vest is being provided with a wearable system for indicating the direction of the source of incoming signals. If the orientation and geographic location of the individual are known via the use of a compass and/or by GPS receiver, the source of the radiation can be pinpointed by triangulation with inputs from other body-worn units. For omni-directional detection, pairs of antennas are provided with feed points or spigots which are fed in phase.

Abstract: A combiner (10) has a glass reflector (11) with first and second curved surfaces (12, 13) each having an optical coating. A first prism (14) has a surface (15) which complements the surface (12) of the reflector (11) and a second prism (16) has a surface (17) which complements the surface (13) of the reflector (11). The surfaces (12 and 13) and the surfaces (15 and 17) are each primed and allowed to dry before being polished. The reflector (11) and prisms (14 and 16) are arranged with respect to one another such that surface (12) forms a well (18) with surface (15) and similarly surface (13) forms a well (19) with surface (17). The wells (18, 19) are completed with a seal (20) at a lower end (21) and bonding agent (22, 23) is injected into the wells (18, 19). The combiner (10) is placed in a vacuum chamber to remove trapped air bubbles and the agent (22, 23) is allowed to cool at a temperature which does not unduly stress the reflector (11) and prisms (14 and 16).

Abstract: The method comprises introducing a tip of a solid phase welding tool between adjacent surfaces of a crack formed in an aircraft skin. The tool is then operated to produce a friction stir weld so as to weld the adjacent surfaces together and thereby repair the crack. Apparatus for performing the method comprises a base having carriage thereon, the arm being pivotally mounted on the carriage and supporting the friction stir welding tool. The position of an arm can be adjusted by a screw which drives the rotating tip of friction stir welding tool into the crack to be repaired. The carriage is then moved along the base to draw the tip along the crack. The apparatus is portable and is particularly useful for repairing a cracked skin on an aircraft.

Abstract: In a video receiver, a photodiode is terminated with one or more junction diodes to provide an output voltage that is a log function of the incident optical power. The termination with the diode provides a nonlinear resistance which converts the output current of the photodiode to a voltage, with the output voltage being the log of the input current due to the nonlinear resistance characteristic associated with junction diodes. The subject system eliminates the necessity of providing a transimpedance amplifier used to obtain a voltage from the photo current of a photodetector and also the requirements for a log amplifier to provide the log of the voltage to give the receiver a wide dynamic range. In one embodiment a PIN diode is provided with a series of termination diodes, with the larger of the number of diodes, the more voltage that is available. The series-connected termination diodes provide a passive low noise system for converting the photo current to a log voltage.

Abstract: A transconductance power amplifier for amplifying a signal to a capacitive load, including a first N-channel enhancement MOSFET transistor operatively arranged to source current to the capacitive load, wherein the first N-channel MOSFET transistor has a threshold gate to source voltage, a second N-channel enhancement MOSFET transistor operatively arranged to sink current to the capacitive load, an operational amplifier operatively arranged to transmit and amplify an input signal to both of the first and second MOSFET transistors, and, means for biasing the first N-channel enhancement MOSFET transistor such that its gate to source voltage is always at or above its threshold when the load draws near zero current so that very little additional gate charge is required to turn it on more fully.

Abstract: A dual uncoupled mode box antenna which includes a conductive bottom horizontal ground plane, and a box structure superimposed on this ground plane. The box structure includes a vertical first conductive side insulated from the ground plane, and a vertical second conductive side insulated from the ground plane positioned in gapped relation to the first side. There is also a vertical third conductive side which is grounded to the ground plane and which is positioned in perpendicular gapped relation to second side. A vertical fourth conductive side is also grounded to the ground plane and is positioned in perpendicular gapped relation to the first and third sides. A conductive top is superimposed over and insulated from the first, second, third, and fourth sides. The first and second sides are fed in quadrature to create either left handed or right handed polarization.

Abstract: A very efficient gate array core cell in which the base core cell consists of a group of 6 PMOS transistors and a group of 6 NMOS transistors. It also includes pre-wiring of 2 of the 6 PMOS transistors, with 2 of the 6 NMOS transistors at polysilicon level or at local interconnect level while leaving the remaining PMOS and NMOS transistors as individual transistors to be interconnected during the functional ASIC metallization process. The core cell also has 2 polysilicon or local interconnect wires embedded in it, which can be used to interconnect transistors for logic function implementation. The core cell defined in this invention is highly flexible and has been analyzed to interconnect all types of logic and memory functions needed for ASIC designs. The layout of the transistors, pre-wiring of the strategic transistors at polysilicon level or at local interconnect level, and embedded polysilicon or local interconnect wires reduce the core cell size significantly.

Abstract: A system is provided for assisting in the detection and tracking of narrowband signals arriving at an antenna array operating over a wide detection bandwidth and in a crowded RF environment. Since the nature of the detection mission is constrained to be a general search, the system does not attempt to detect signals of interest via matched filtering mechanisms (i.e. training sets), but exploits general properties such as power, frequency, time and angle of arrival. For the purposes of providing sufficient Frequency/Time resolution as well as to avoid array overloading in the detection process, the digitized wideband streaming data is frequency channelized using a sufficiently high revisit rate for the signal set of interest, constrained by the required feature detection accuracy or environment adaption rates. Within each frequency subchannel, efficient array signal subspace tracking techniques are used to separate and track spatially separated cochannel signals.