Abstract: A precision, micro-mechanical semiconductor accelerometer of the differential-capacitor type comprises a pair of etched opposing cover layers fusion bonded to opposite sides of an etched proofmass layer to form a hermetically sealed assembly. The cover layers are formed from commercially available, Silicon-On-Insulator (“SOI”) wafers to significantly reduce cost and complexity of fabrication and assembly. The functional semiconductor parts of the accelerometer are dry-etched using the BOSCH method of reactive ion etching (“RIE”), thereby significantly reducing contamination inherent in prior art wet-etching processes, and resulting in features advantageously bounded by substantially vertical sidewalls.

Abstract: A sensor array includes a fiber optic cable and at least one electro-optical conversion unit connected to the cable. The electro-optical conversion unit includes a housing formed of mating upper and lower covers. The housing includes an interior cavity for receiving a phase modulator module, a strength member and an interferometer formed by fibers connected to various splices and couplers in combination with the phase modulator module. The interior of the housing is filled with a fill material for holding the position of optical fibers to thereby protect against environmental factors such as shock and moisture.

Abstract: The invention comprises an alignment element for a multiple channel sight and method. In accordance with one embodiment of the invention, an alignment element (456) may comprise a first prism (492) and a second prism (494). The second prism (494) may be disposed proximate to the first prism (492). An adjustment device (506) may rotate the first prism (492) with respect to the second prism (494) to deviate an image of a first channel (54, 56) at an image plane (300).

Abstract: A “Rendering Process and Method for Digital Map Illumination Intensity Shading” is disclosed that assigns an illumination intensity to pixels in a video display imaging a mapped terrain. The process comprises the steps of: providing a rectangular grid array of altitude values covering an area to be shaded. Each altitude value has a map position characterized by a coordinate location referenced to a first and second coordinate axes crossing orthogonally at an origin. Each coordinate location has a first and second value. Each first and second value characterizes the distance of the respective coordinate location from the origin. The map area is divided into an array of contiguous triangles. Each triangle area has a perimeter bounded by three straight line segments passing between three coordinate locations. The video display has pixel areas that corresponding to each respective triangle area. A normal vector is calculated for each triangle area.

Abstract: A system for sensing subterranean acoustic waves emitted from an acoustic source includes a plurality of laser sources, a plurality of subterranean optical sensors, at least one optical detector, and electronics. The laser sources each emit light at a different frequency. The subterranean optical sensors receive the light and alter the light in response to the acoustic waves. The optical detector receives the altered light and outputs an electrical signal. The electronics receives the electrical signal and converts it into seismic data format. Preferably, the light emitted from the optical sources is modulated at a plurality of modulation frequencies. The electronics can be used to demodulate the signal. The electronics may demodulate the electrical signal by mixing the signal with periodic waveforms having frequencies corresponding to the modulation frequencies and twice the modulation frequencies.

Abstract: The invention is a method and apparatus for obtaining an accurate value x1c of a variable x1 based on an estimate x1e that is a function of K variables x1, x2, . . . , xk, . . . , xK. The method comprises the steps of (a) obtaining a plurality of estimates x1e, x2e, . . . , xke, . . . , xKe of the variables x1, x2, . . . , xk, . . . , xK over a method-execution time period, the values of the variables x1, x2, . . . , xk, . . . , xK changing or being changed during the method-execution time period; (b) obtaining from an external source the actual values x1a of x1 during the method-execution time period; (c) defining a compensation model &dgr;x1 that is a function of one or more of the estimates x1e, x2e, . . . , xke, . . . xKe of the variables x1, x2, . . . , xk, . . . , xK, the compensation model being further defined by I unknown constants a1, a2, . . . , ai, . . . , aI; (d) applying an operator G to the values of x1e−x1a and &dgr;x1; (e) determining the values of a1, a2, . . . , ai, . . .

Abstract: The invention corrects for rotational misalignment of images having a prominent periodic structure in a preferred direction, particularly imaged text pages. It preferably also finds the degree of correlation between different images. First the rotational misalignment of an imaged page is detected and corrected, bringing the page into alignment with an axis. The angle of rotation of the page is detected by performing a linear regression analysis on filtered, two-dimensional power spectral density distribution of the page, to find the angular orientation of the periodic components. In the preferred embodiment, two imaged pages are then cross-correlated, preferably by an optical correlator, to find the degree of correlation between the pages.

Abstract: These and other objects of the present invention are achieved by inserting electrically conductive rings and a bearing into a mold before a slip ring body is injection molded. During the injection molding process, the rings and the bearing are partially encapsulated by the injected plastic and retained. Plastic is prevented from entering the race of the bearing by using a pair of additional plastic inserts which prevent plastic from entering the bearing race. When the injected plastic cools, the plastic shrinks and compresses the bearing thereby preventing axial movement. Wires attached to the rings are also encapsulated by the plastic material during the injection molding process.

Abstract: The present invention determines the geolocation of an emitter, using at least one observer measuring signal change while moving on at least two observation tracks. The measurement of emitter signal change is begun between a first observer position and a second observer position. The second observer position is predicted at the time the last measurement from which signal change will be derived is made. The method utilizes knowledge of the measurement start and end points to determine a second pair of observer signal-change measurement start and end positions such that the emitter line-of-position (LOP) determined by the second signal change measurement will intersect the LOP associated with the first signal change measurement at possibly multiple points, but at each of these point intercept orthogonally to within the signal change measurement errors.

Abstract: Apparatus for measuring concentration of oxygen includes a plurality of status displays, identifying concentration status relative to a plurality of thresholds, an alarm for immediate and prominent identification of status relative to a threshold of particular significance, and a quantitative display indicative of an actual concentration. Although measurements are performed and results are indicated relative to a number of thresholds, only a single calibration procedure is required, using only a single calibration gas. The apparatus is calibrated by adjusting a circuit parameter of one of the circuit components to vary a sensed output value to correspond to a narrow range surrounding the known concentration of the calibration gas. Both the circuit parameter and the actually sensed output value are stored. In a monitoring operation, the circuit parameter is retrieved to reset the circuit component to its calibrated setting.

Abstract: An acoustic array includes amplifiers and sensor subarrays, both of which are placed along rungs that connect a return distribution bus with both a signal distribution bus and a pump distribution bus. By placing the amplifiers along the rungs, separate buses can be used for distributing the optical signal and the pump energy for the amplifiers, thereby facilitating the use of standardized couplers. Time division multiplexed sensor subarrays are advantageously connected to unique combinations of laser signal sources and signal return buses, in which the laser signal sources generate different optical wavelengths that are multiplexed on the signal return buses. Optical sources include intensity modulators on either side of an amplifier to eliminate extraneous noise between optical pulses. In addition, amplified spontaneous emission (ASE) filters may be advantageously used to reduce optical noise at wavelengths other than those of interest.

Abstract: A night vision device (10) includes an improved power (62) that regulates the output brightness of the image intensifier tube (14) of the device (10) according to the two functions of MCP voltage control and photocathode gating duty cycle control. These two functions operate in sequence—the MCP voltage control operates prior to the duty cycle control with increasing input illumination to the image intensifier—in order to provide automatic brightness control and bright source protection while maximizing the high light level image resolution and maintaining the signal-to-noise ratio of the image intensifier at an acceptably high level.

Abstract: A sensor array cable and method of construction thereof utilizing a sensor/interlink assembly to facilitate the relatively easy and inexpensive installation of a sensor device in a cable that includes a strength member to provide tensile strength to the cable, optical fibers or wires for carrying electrical or optical energy to and from the sensor device, and a protective outer jacket. A portion of the protective outer jacket is removed allowing access to the inner strength member and optical fibers. A segment of the strength member is removed and an interlink/sensor assembly is installed in its place. The interlink serves to maintain the tensile strength of the cable. Optical fibers and/or electrical wires are connected to the sensor device for operation. The interlink/sensor assembly and associated optical fibers and electrical wires are then enclosed in an overmold which is sealed to the outer protective jacket.

Abstract: A night vision device (30) with an image intensifier tube (34) including an improved microchannel plate (42) which has a thickness no more than about 110% of the value indicated as optimum by the theoretical Universal Gain Curve. Accordingly, the microchannel plate (42) provides an improved resolution, and reduced operating voltage, and still provides a level of electron gain favorably comparable to conventional microchannel plates.

Abstract: A system for sensing subterranean acoustic waves emitted from an acoustic source includes a plurality of laser sources, each emitting light at different frequencies; a plurality of subterranean optical sensors, receiving and altering the light in response to acoustic waves; at least one optical detector, receiving the altered light and outputting an electrical signal; and electronics, receiving the electrical signal and converting it into seismic data format. Light from the optical sources is modulated at a plurality of modulation frequencies. The electronics can demodulate the signal by mixing the signal with periodic waveforms having frequencies corresponding to one and two times the modulation frequencies.

Abstract: The invention is a method and apparatus for determining the fringe number for a fiber-optic gyro. The fiber-optic gyro comprises a light source feeding an interferometer which in turn feeds a detector. The detector output signal is a function of the fringe number and a plurality of controllable parameters. The method comprises the steps of (1) determining the values of the controllable parameters and (2) extracting the fringe number from the detector output signal utilizing the values of the controllable parameters.

Abstract: In a wrapped ring manufacturing process for slip ring assemblies, the assembly is heated to expand a gap between ends of the slip ring. A conductive material is then used to fill the expanded gap, to assure compression of the conductive material and to eliminate cracks therein. The filled gap is electroplated with a precious metal to form a layer of material of uniform hardness, wear resistance, electrical conductivity and environmental resistance around the entire perimeter of the slip ring.

Abstract: The present invention provides an electrical interconnect system using multiple grounding methods to reduce or prevent spurious signals from interfering with high density contacts carrying high speed transmissions. A first connector includes an insulative pillar partially surrounded by a plurality of signal contacts. A central ground contact is at least partially located within the insulative pillar. A second connector includes a plurality of flexible signal contacts for mating with the signal contacts adjacent the insulative pillar. Additionally, flexible ground contacts in the first connector are in contact with an electrically conductive shield. The second connector also includes a central ground contact for receiving the central ground contact of the first connector. The ground contacts provide a first method of providing a ground path to reduce spurious signals from entering the signal path.

Abstract: A system and method for improving the accuracy of altitude determinations in an inertial navigation system. Pressure measurements available to the inertial navigation system are used to initially calculate an estimated pressure altitude using the standard day model for the atmosphere. Temperature measurements are further utilized in the physical relationship between temperature, pressure, and altitude to compute a second computed altitude. A change between subsequent second computed altitudes is calculated and compared with a respective change in the computed pressure altitude in order to generate a correction value. The correction value is then used to modify the computed pressure altitude to generate a more accurate determination of the absolute altitude of the inertial navigation system.

Abstract: A linear beam device having a multi-stage depressed collector is provided with a single crowbar circuit that quickly removes all voltages from the collector electrodes upon detection of an arc between the collector electrodes. The linear beam device comprises a cathode and an anode spaced therefrom that are operable to form and accelerate an electron beam. A collector having a plurality of successive collector electrodes is arranged downstream from the anode to collect electrons of the electron beam. At least one power supply is coupled to the collector and provides a plurality of distinct voltage levels to respective ones of the collector electrodes. The power supply comprises a plurality of serially coupled filter capacitors, with each one of the filter capacitors being charged to a respective difference between adjacent ones of the distinct voltage levels. A crowbar circuit is coupled across the plurality of filter capacitors.