Abstract: Solar tabs are provided which have thermal emissivity and absorptivity properties designed to increase the attitude-control torques that can be generated with rotatable wings in a spacecraft. These increased torques enhance the ability to offset attitude-disturbance torques which typically tend to alter the attitude of a spacecraft from a desired attitude. The tabs include highly absorptive and nonemissive front faces, highly emissive back faces and a high thermal conductivity between the front faces and the back faces.

Abstract: A gimbal system includes a pair of stepper motors that drive respective drive trains of a differential drive assembly such as a differential gear assembly. Either the drive ratios or the step sizes for the two motors are offset from each other to provide four modes of operation, including modes for improved resolution and faster slew rate, and two intermediate modes with more balanced resolution and slew rate.

Abstract: A memory cell is constructed using a ferroelectric capacitor having an insulator formed of a ferroelectric material that has a zero field capacitance which is controllably dependent upon the electrical charging path by which the zero field capacitance is reached. Preferably, the material is characterized by a first zero field capacitance following saturation of the polarization by a first applied voltage applied in a first polarization direction, and a second zero field capacitance following saturation of the polarization by the first applied voltage applied in the first polarization direction followed by partial depolarization by a second voltage applied in a direction opposite to the first polarization direction. A second ferroelectric capacitor or a linear capacitor may be placed in parallel with the ferroelectric capacitor to form a two-capacitor memory cell. Data may be read to or from the capacitor cell without impairing the state of the stored data.

Abstract: An improved circuit and method of making precise time of arrival measurements on optical pulse data of relatively varying widths. The invention provides an analog input pulse representing received optical pulse data, along with a delayed version of the analog input pulse. The time of delay is set such that the original analog pulse and the delayed analog pulse cross each other at a predetermined point. This cross-over consistently occurs at the same point on the signal independent of the size or shape of the analog pulse. Preferably, the cross-over occurs at approximately 70% of the analog pulse amplitude. The cross-over point between the original pulse and the delayed pulse triggers the generation of the leading edge of a time of arrival pulse.

Abstract: An optical device comprising a glass prism that functions as a 180.degree. fold prism and a quarter-wave retarder. The optical device comprises a 180.degree. folding glass prism having first and second total internal reflecting surfaces that provides a 90.degree. phase shift of laser energy at a plurality of wavelengths propagating therethrough. The composition of the glass prism is selected so that its refractive index provides a 45.degree. shift at each of first and second total internal reflecting surfaces. Dispersion in the glass is chosen to be small enough so that the phase shift of the energy propagating therethrough is relatively insensitive to wavelength. Consequently, the prism also functions as a quarter-wave retarder at the plurality of wavelengths.

Abstract: A laser system includes a laser resonator cavity having a resonant path and an Er,Yb:glass lasing element with an output of from about 1.5 to about 1.6 micrometers within the laser resonator cavity. A diode array optically pumps the lasing element to emit light. A Q-switch lies along the resonant path within the laser resonator cavity. The Q-switch is formed of a host material having a concentration of uranium ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch is preferably a uranium-doped fluoride such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.

Abstract: An optical apparatus monitors the entire panorama in low resolution and simultaneously monitors a selected portion of the panorama in high resolution. For the panoramic portion of the apparatus, a mirror having a convex surface of revolution with a hole therein is used. The higher resolution part of the apparatus uses a pointing mirror positioned above this hole. The panoramic and higher resolution views are imaged through lenses or optical components onto a detector. The panoramic view is imaged onto the detector as an annulus of light in which either higher or lower elevational angles of the panorama are imaged further away from the detector's center depending upon how the convex mirror is configured. In this way, the resolution of that portion of panorama that is imaged further away from the detector's center is enhanced. The higher resolution view is imaged to the center of the annulus.

Abstract: Boresighting apparatus that includes a multispectral reflective collimator combined with an adjustable rhomboid reflector that allows boresighting of any wavelength sighting, pointing, aiming or rangefinding device disposed on a small arms weapon. The boresighting apparatus comprises a housing and a small arms weapon adapter for securing the housing to small arms weapons having different calibers. An illuminated or heated target is disposed in the housing for selectively providing an image of an illuminated or heated target pattern. A power source is coupled to the target for providing power to selectively illuminate or heat the target. An adjustment mechanism is provided for incrementally adjusting the optical location of the target and thus the location of the target pattern. A mirror, such as an off-axis parabolic mirror, is disposed to reflect the image of the illuminated or heated target pattern along a visual optical path.

Abstract: A system and method that provides an electronic indication that unauthorized access has been gained to a system. The mechanisms used by the present invention cannot be forged, bypassed, or subverted. In fact, even persons authorized to access the environment cannot do so without leaving evidence. When an intrusion is detected, a random number is generated. This random number, referred to as an audit count, is then encrypted and stored, and a sequence number is incremented. To recover this information at a later time, a trusted individual inserts an external device containing a decryption key. The decryption key is extracted, and the encrypted audit count and sequence number are decrypted and displayed. Periodic verification that the audit count and sequence number have not changed provides assurance that access has not been gained to the system.

Abstract: A software-based resolver-to-digital converter (RDC) (80) for computing an angle of rotation .THETA. 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 .THETA. and output the computed value to system circuitry (31) for processing to enhance system operation.

Abstract: A system and technique for directing intensity modulated electromagnetic energy. The inventive system (10) includes an intensity modulated source of electromagnetic energy (12). Individual elements (22) in an array of energy directing elements (15) are activated in sync with the modulation of the energy source (12). In a particular implementation, the source (12) is a laser. The intensity of the laser is reduced during each successive field per frame. The energy directing elements (15), in this case, light directing elements, are implemented with an array of digital micromirrors. The light source (12) is modulated in intensity in accordance with a fixed modulation scheme. The mirrors (22) are selectively activated relative to the light source modulation scheme. Hence, the invention provides a gray scale output while allowing the time between mirror flips to be constant.

Abstract: A cryocooler system (20) includes a heat sink (24), such as a Stirling cycle heat engine having a cold cylinder sleeve (26) and a cold gas pocket region (32) within the cold cylinder sleeve (26). An adapter (36) is sealed to the cold cylinder sleeve (26) with a hermetic seal, such as a welded joint (38). A copper cold tip (28) has a first end (34) directly contacting the cold gas pocket region (32) within the cold cylinder sleeve (26). The periphery of the cold tip (28) is welded, preferably by frictional welding, to the adapter (36). The cold tip (28) thereby provides a hermetic seal to the end of the cold cylinder sleeve (26) to retain the working gas within the cold gas pocket region (32) and also to provide an unimpeded heat flow path to the cold gas pocket region (32).

Abstract: A wideband, wide angle sidelobe cancellation array system is disclosed. The system includes a main array formed of a plurality of regularly spaced elements, and an auxiliary array formed of two auxiliary antenna elements spaced from the outermost elements of the main array a distance equal to one-half the spacing of the main array elements. The received signals from the main array elements are combined to form a main array signal. The contributions from the auxiliary array elements are combined to form an auxiliary array signal. The two array signals have a good amplitude and phase match over a wide frequency and angle range. The main array and auxiliary array signals are then combined to form a system array signal wherein the sidelobe energy in the main array signal has been substantially cancelled. The system can be made an adaptive one by the addition of adaptive RF phase and amplitude weighting to the auxiliary array signal prior to combining with the main array signal.

Abstract: A plurality of threshold detectors is provided to pass analog signals of predetermined and varying threshold values. An analog to digital converter converts these analog signals to binary 1s and 0s. A target detected on each radar beam sweep is a 1 and no target is a 0. These binary numbers are then stored in a reversible up-down counter. At the first signal received, the counter counts up on hits (binary 1) and counts down on misses (binary 0). When the contents of the counter reaches a predetermined count, a target's leading edge is declared. At this time, the counter is then reset and proceeds to count up on misses and down on hits until the aforesaid predetermined count is attained, wherein a trailing edge is then declared.

Abstract: Continuous, elongated nickel plated graphite fibers are bound with an epoxy and are formed into a structural shape (11). An area (13) of the epoxy is removed by bead blasting to expose a layer of the plated graphite fibers (14), which are aligned in the desired direction of radio frequency current propagation. The bead blasted area (13) is then silver plated to obtain good contact to the plated graphite fibers (14) and resultant high conductivity from the structural shape (11).

Abstract: A portable gas purge and fill system. The inventive system (10) includes a portable housing having gas inlet and outlet couplings. An electronic pressure gauge (30) is disposed within the housing (11) for measuring the pressure of the fluid at the outlet (24) thereof. A self-check mechanism (32) is disposed within the housing (11) for verifying calibration and operation of the electronic pressure gauge (30). In a specific implementation, the invention further includes a pressure regulator (20) disposed within the housing and connected between the inlet (12) and outlets (24) thereof. A second gauge (14) is included for measuring the pressure of the fluid contained in the source. First, second and third two-way valves (18, 22, and 28) are included. The first two-way valve (18) is mounted between the second gauge (14) and the pressure regulator (20). The second two-way valve (22) is located between the pressure regulator (20) and the outlet (24).

Abstract: A nested cup dipole feed capable of collinear polarization for all bands, and frequency staggering of one linear polarization with respect to the orthogonal linear polarization. The dipole elements for all bands are collinearly placed, making one linearly polarized set to be orthogonal to the other collinear sets. One collinearly placed dipole can be tuned differently from the orthogonal ones to permit frequency staggering at the crossover frequencies, thus permitting at least high gain for one polarization.

Abstract: A missile launch safety enhancement apparatus (135) for inhibiting the launch sequence of a missile launched from an aircraft-based or land vehicle-based missile launch system. The apparatus (135) incorporates means for producing a prefire signal (102a). The prefire signal produced is then compared to a reference signal level by comparing means (167). If the prefire signal is not below the reference signal level by a predetermined amount, interrupting means (216, 240) inhibits the firing sequence of the missile and thus prevents the missile from being launched. If the prefire signal is below the reference signal level by a predetermined amount indicating proper current drawn by the circuit, the firing sequence is not inhibited, and the missile is launched.

Abstract: A two-channel field sequential display system utilizes both simultaneous and sequential color display methods to display full color images in a way that is less complex, smaller in size and less costly than prior art additive color systems, while exhibiting higher light output and fewer temporal visual effects than prior art single-channel field sequential color display systems. The two-channel field sequential display system displays two of three primary colors that make up the image simultaneously during a portion of a display frame and displays the third primary color sequentially during a subsequent part of the display frame. The two-channel field sequential color display concept may be applied to any projection system which combines individual monochrome projector outputs to form an image on a screen or to any display technique that is capable of superimposing two images.

Abstract: A polarizing beamsplitter (PBS) that can be used with reflective light valve displays includes two polarizing surfaces. A light source projects opposing readout beams onto the polarizing surfaces, which reflect linearly polarized (S or P) components of the readout beams. The polarized readout beams illuminate respective portions of a reflective light valve cell that bears an image intensity pattern. The cell spatially modulates the readout beams' polarization in accordance with the image intensity pattern and reflects the polarization modulated beam back towards the polarizing beamsplitter. The PBS spatially analyzes the readout beams' intensities in accordance with their polarization modulations.