Abstract: An equalization system and method. In a most general sense, the inventive equalization system includes first and second filters for filtering an in-phase component of a received signal in accordance with first and second sets of coefficients, respectively. The system includes third and fourth filters for filtering a quadrature component of the input signal in accordance with third and fourth sets of coefficients, respectively. The outputs of the first and third filters are subtracted to provide an equalized in-phase output signal and the outputs of the second and fourth filters are added to provide an equalized quadrature output signal. In the illustrative embodiment the filters are finite impulse response filters and the coefficients are provided by a microprocessor. In accordance with the present teachings, the filters are implemented in a general purpose filter. The delay elements of the filters are calculated in accordance with a mean square error algorithm.

Abstract: A versatile signal processor. The inventive signal processor includes a plurality of filters which are selectively interconnected to provide a variety of digital signal processing functions. In the illustrative embodiment, each filter is adapted to multiply input data by a coefficient. Further, each filter includes adders for accumulating the products. The coefficients are provided by an external processor which configures the general purpose filter to a particular function, such as a general purpose filter, a Hilbert filter, a finite impulse response filter, an equalizer, a beamforming network, a convolver, a correlator, or an application specific integrated circuit by way of example. When interconnected in accordance with the teachings provided herein, these circuits may be used to provide a digital receiver.

Abstract: A passively operated thermal diode for controlling heat transfer from heat-generating electronic components to an external environment through an airframe is provided. The thermal diode comprises: (a) an electronics package within the airframe; (b) a heat-transferring mechanism thermally connected to the electronics package and controllably disengagable from thermal contact with the airframe at a predetermined temperature; (c) a shape-memory alloy component having a phase change at the predetermined temperature for thermally disconnecting the electronics package from the airframe once the predetermined temperature is exceeded; and (d) a spring for maintaining the heat-transferring mechanism in thermal contact the airframe below the predetermined temperature. The present invention solves the problem of heat transfer by introducing a shape-memory-alloy sensor-actuator component.

Abstract: A centrally-obscured reflective telescope having a semi-active focus and thermal compensation system. The telescope has a housing having an input window, a primary mirror, a secondary mirror suspended between the input window and the primary mirror by support struts, an optional tertiary mirror, and an optional fold mirror. The system includes one or more heating elements respectively disposed on each of the support struts. A first temperature sensor (disposed on the primary mirror) generates a reference temperature, a second temperature sensor is disposed on the secondary mirror, and one or more third temperature sensors are disposed on each of the support struts. A temperature compensation controller is coupled to the heating elements and temperature sensors and controls the heat output of the plurality of heating elements to heat the support struts and control the position of the secondary mirror relative to the primary mirror.

Abstract: An infrared-transparent structure includes a first infrared-transparent element that is transparent to infrared radiation in the 3.6-7 micrometer wavelength range, preferably coated with a zinc-sulfide antireflective coating, and a layer of a solvent-free, infrared-transparent polymer transparent on the first infrared-transparent element. The polymer is formed of an addition-cured silicone, such as addition-cured dimethyl silicone, and a small amount of an adhesion promoter, such as 3-glycidoxypropyltrimethoxysilane. The polymer layer may either be a surface layer, or it may be used as an adhesive between the first infrared-transparent element and a second infrared-transparent element.

Abstract: A pulse tube expander includes a regenerator, a pulse tube, a porous plug phase shifter, and a surge tank, in series gaseous communication with each other. The porous plug phase shifter is made of a porous material such as a sintered mass or a packed solid bed of distinct, free-flowing bodies. The porous plug phase shifter introduces a phase shift between the pressure wave and the mass flow rate in the pulse tube expander. The porous plug phase shifter is resistant to clogging due to contamination that may be present in the system.

Abstract: An optical system has an extended boresight source including a boresight light source that produces a light beam, a condenser lens that receives the light beam from the boresight light source, a spatial light integrator that receives the light beam from the condenser and mixes the light beam to reduce its spatial inhomogeneities, a constriction through which the light beam from the spatial light integrator is directed, and a collimator that receives the light beam which passes through the constriction and outputs a boresight light beam. The boresight light beam is typically provided to a sensor imager that uses the boresight light beam to establish its centroid.

Abstract: A passive proximity fuze. The inventive fuze (10) is adapted to be mounted on a munition (11) and includes a receiver (16) adapted to lock on to a signal transmitted by a target transmitter (12). The receiver (16) detects a Doppler shift in the signal as the munition approaches the target. When a closest point of approach is reached the Doppler shift changes from increasing to decreasing. The inventive fuze (10) includes a mechanism for detecting this change in the Doppler shift and provides a detonation signal in response thereto. In the illustrative embodiment, the receiver (16) is an FM receiver. The mechanism for detecting a change in the Doppler shift may be implemented with discrete analog circuitry or digital circuitry. In an illustrative analog implementation, first and second resistive/capacitive networks (R1C1 and R2C2) are employed to compute a second derivative of the Doppler shift signal output by the receiver (16).

Abstract: A multi-resolution feature extraction method and apparatus. In the illustrative embodiment, the feature extractor includes circuitry for receiving and transforming a time variant data signal into a multi-resolution data signal. The multi-resolution data signal is compared to each of a plurality of object templates. The system then generates a feature vector based on a correlation of the multi-resolution data signal to one of the object templates. The multi-resolution feature extraction method employs object templates formed by transforming time variant image data for each of a plurality of objects into a respective multi-resolution template and averaging all templates for each respective object. The method includes steps for transforming an incoming time variant data signal into a multi-resolution data signal, comparing the multi-resolution data signal to each of the object templates, and generating a feature vector when the multi-resolution data signal correlates to one of the object templates.

Abstract: A control system for a rolling missile that has a seeker head including an optical system and a heat detector assembly. The optical system including a primary reflector, a secondary reflector, a reticle/lens assembly, and a fiber optics assembly operatively associated with the reticle/lens assembly. The fiber optics assembly is constructed so as to translate images appearing near the optical axis of the optical system to a radially displaced point on the reticle/lens assembly to provide a more efficient chopping of the image by the reticle/lens assembly thus providing continuous pulses to the heat sensitive detector assembly.

Abstract: Self aligning, blind mating connector bodies are provided for connecting to mating connector bodies. One embodiment of the connector body has an annular housing with two slots disposed 180 degrees apart. An inner body has two dowel pins disposed at locations corresponding to the slots in the annular housing. A compliant O-ring is disposed between and is resiliently coupled to the inner body and the annular housing. The inner body is free to rotate relative to the annular housing about an axis defined by the dowel pins to provide single axis gimbal motion. Another embodiment of the connector body has an annular housing with two holes disposed 180 degrees apart. An inner body has two dowel pins disposed at locations corresponding to the holes in the annular housing. An external housing ring is connected to the annular housing using a second pair of dowel pins located 180 degrees apart that are disposed at 90 degrees with respect to the first set of dowel pins.

Abstract: An optical system includes a window, an optical corrector formed of a curved piece of a transparent material having a front surface and a back surface, and a sensor system with a sensor positioned such that the optical corrector is between the window and the sensor. At least one of the front surface and the back surface of the optical corrector is a segment of a convex aspheric curve rotated about a center, otherwise known as a torus.

Abstract: A system and method of finding a detection threshold that separates real scene objects seen through an optical system from sensor fixed artifacts. The inventive system continuously scans the sensor so that objects in the scene move in an inverse sense relative to the scanning motion while fixed frame artifacts remain fixed in focal plane coordinate system. The difference in temporal behavior is used to discriminate against fixed frame artifacts. The inventive system finds a detection threshold that maximizes the portion of a target that may be segmented while avoiding setting the threshold so low that it merges spatially adjacent artifacts in with the target.

Abstract: A dual cavity multifunction laser comprising a diode-pumped, contact cooled, slab laser head that supports two different length unstable resonators. The laser produces short (<8 ns), low energy 1 &mgr;m pulses or long (>15 ns), higher energy 1 &mgr;m pulses from the same laser system at different repetition rates, if desired. The output from each resonator can be separately optimized for different operating modes such as target designation and target profiling. The unstable resonators use independently optimized super Gaussian output couplers to generate high quality beams for each of the high and low pulse energy modes. The resonators also share a common bounce path to minimize intracavity losses and thermally induced birefringence for both resonators.

Abstract: A soiled piece of fabric is cleaned by mechanical agitation while the fabric is simultaneously subjected to acoustic energy in a gaseous environment wherein the piece of fabric is not immersed in a liquid cleaning medium. Mechanical agitation may be by gas jet action and/or by tumbling. The acoustic energy vibrates the fibers of the fabric to enhance the cleaning action. The piece of fabric may be chemically treated to mobilize the soil.

Abstract: A steerable optical arrangement. The inventive arrangement includes a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about the optical axis. In accordance with the inventive teachings, the first prism and/or the second prism have at least one surface contoured to correct for optical aberration. In the illustrative embodiment, the first and second prisms are Risley prisms. In addition, the illustrative implementation includes a first motor arrangement for rotating the first prism about the optical axis and a second motor arrangement for rotating the second prism about the optical axis. A controller is provided for activating the first and second motors to steer the beam at an angle &phgr; and nod the beam at an angle &thgr;. At least two surfaces at least one prism is contoured to correct for astigmatism, coma, trefoil and other non-rotationally symmetric aberration.

Abstract: An arrangement (10) for efficiently shifting energy received at a first wavelength and outputting the shifted energy at a second wavelength. The arrangement (10) includes a laser (12) and an optical parametric oscillator (14) of unique design. The oscillator (14) is constructed with a energy shifting crystal (20) and first and second reflective elements (16) and (18) disposed on either side thereof. Light from the laser (12) at a fundament frequency is shifted by the crystal and output at a second wavelength. The second wavelength is a primary emission and induces a secondary emission of energy in the crystal. A novel feature of the invention is a coating applied on the reflective elements (16 and/or 18) for minimizing the secondary emission. This constrains the energy to be output by the arrangement (10) at the wavelength of the desired primary emission. In the alternative, the arrangement (10) may be optimized to output one or more of the secondary emissions.

Abstract: The present invention relates to an improved electrical interconnection assembly adaptable for creating electrical connections between spaced-apart sections of a high performance missile assembly. Because the electrical connection must extend outside the missile, a plurality of electrical interconnections are integrally formed within a protective housing that is, itself of aerodynamic configuration. The cables may take the form of flat wires, or printed wire assemblies integral with the housing. Pre-stressed foam is formed in the housing to insulate the electrical interconnections. Wire mesh is preferably mounted in the housing between the interconnections and the outside of the housing to protect the interconnections from Electro-magnetic Interference (EMI).

Abstract: A missile seeker. The inventive missile seeker includes a dome within which a novel optical arrangement is retained. The optical arrangement includes a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about the optical axis. In the illustrative embodiment, the first and second prisms are Risley prisms. In addition, the illustrative implementation includes a first motor arrangement for rotating the first prism about the optical axis and a second motor arrangement for rotating the second prism about the optical axis. A controller is provided for activating the first and second motors to steer the beam at an angle &phgr; and nod the beam at an angle &thgr;. In a specific implementation, the first prism and/or the second prism have at least two surfaces contoured to correct for optical aberration. A teaching is provided to contour the surfaces to correct for astigmatism, coma, trefoil and other non-rotationally symettric abberation.

Abstract: A software-based resolver-to-digital converter (RDC) (80) for computing an angle of rotation &THgr; of gimbal-mounted instrumentation (16) in a gimbal system. The RDC (80) computes the angle of rotation of the instrumentation using parameter signals received from a resolver (32) in the system. The parameter signals, along with a resolver reference signal are input into a multiplexor (60) and are multiplexed. The signals are then fed to an analog to digital converter (38) and converted to digital form. The digital signals are then input into a processor (36) associated with the system. This processor, in addition to performing numerous system computations, is programmed through appropriate software to filter the digital signals received, compute the value for the angle of rotation &THgr; and output the computed value to system circuitry (31) for processing to enhance system operation.