Abstract: Extended laser life may be obtained by measuring, with an ammeter AM, the discharge current applied to a laser (either linear or a ring laser gyro RLG), measuring the intensity of the resulting light beam with an intensity monitor IM, calculating the noise with an integrated circuit IC, and maintaining the discharge current at the lowest level possible which is consistent both with maintaining the intensity above the intensity service limit and the noise below the noise service limit.

Abstract: An improved fly by wire or fly by light system which provides for a smooth manual override of the autopilot function by allowing the pilot to modify the autopilot command to the control surfaces by physically manipulating the yoke to a position different than that commanded by the autopilot.

Abstract: An improved microwave radar antenna including a plurality of linear waveguides arranged in a two dimensional array with each linear waveguide having a mounting flange along the bottom narrow edge of the waveguide for attachment to the ground plane of the antenna by the conductive epoxy. Also disclosed is a method of manufacturing an improved microwave antenna where flanged linear waveguides are milled to provide for radiator slots and then are affixed to a attentive ground plane along the flanged edge of the waveguide by a conductive epoxy.

Abstract: An apparatus for housing a focal plane array includes a tubular metal stem for housing a cryostat inside of it, and a hollow conical metal housing having its narrow end brazed onto the end of the tubular metal stem. A ceramic electrical interconnection assembly is rigidly sealed onto the wide end of the housing, having embedded electrical connections for providing electrical connections between the interior and exterior of the assembly. A metal ring-shaped mounting structure is rigidly attached to the ceramic interconnection assembly. A ceramic coldplate is sealed over the other end of the rigid metal tube in the interior of the structure for holding the focal plane array. The rigidity of the structure provides a known positional relationship between the coldplate and the mounting ring, to facilitate positioning the focal plane array during dewar installation. A metal cap is sealed to the mounting ring to provide a reworkable, hermetic closure.

Abstract: An improved three dimensional head-up display utilizing a holographic optic element diffraction grating to selectively reflect light emitted from a first CRT into a first of the pilot's eyes and reflecting light from a second CRT into the second of the pilot's eyes.

Abstract: An electric pump comprises a housing (22) that encloses a stack of waveplates (18) in which electrically created traveling waves forcefully move fluid (20) from an inlet duct (24) to an outlet duct (26). Each waveplate is made of shear type transducer material that is segmented by film electrodes, the electrode planes lying perpendicular to the direction of fluid flow. Electrode sets are stimulated by a multiphase electrical power source. The pressure at wave crest contacts is electrically controlled to hermetically trap fluid portions between waves, thereby achieving high throughput against high pressure differential. Rubbing is essentially absent throughout the pump, life shortening mechanisms being few and benign. High electromechanical efficiency obtains when waveplates are stimulated by electrically resonant frequencies. Pump variants include variable wavelength, variable wave amplitude, and tapered waveplates for improved effectiveness with compressible fluids.

Abstract: The tuner for ring laser gyro dither mechanism shown herein is a disk 32 which is bolted to the top end 48 of a base mounted vane 24 of the gyro. All such base mounted vane top ends 48 are thus bolted together, thereby stiffening the spring constant of the azimuthal vibration 52 of the top ends 48, thus increasing the frequency of the dither mechanism.

Abstract: An apparatus and method are disclosed for characterizing the surface of mirrors in which a cross-grid type phase grating is illuminated from behind by light reflected from the mirror so as to create a grid-like interference pattern when observed along an observation axis. The fringe lines in the generated or observed interference pattern are correlated to the grating and observed for relative displacement from the grating axis. Apparent fringe index numbers for the fringe lines are used to determine coefficients for a plurality of monomial series which are in turn used to derive Zernike coefficients from which a wavefront contour is obtained. In order to reduce alignment errors during analysis, each fringe line is subtracted from the next lower order line and before monomial coefficients are determined.

Abstract: The present invention is useful for quickly releasing an object which is being moved by an actuator. Generally actuators of the piezoelectric type move objects slowly. For applications where an object must be quickly moved such as when releasing brakes or reinserting a control rod in a reactor core an actuator should have a quick release feature. The invention uses a set of actuators which contact a bolt and moves the bolt with smooth walking motion. The bolt in turn is driven by the actuators such that it engages an object with smooth walking motion to move or position the object. When the object is to be released the actuators are removed from contact from the bolt thereby releasing the object.

Abstract: An integrated attitude director indicator and horizontal situation indicator is disclosed that utilizes stereopsis to combine information that normally requires two display surfaces onto a single electronic display. One embodiment of the display comprises left and right eye versions alternately presented on the display in synchronism with alternate eye shuttered lenses worn by the viewer. The viewer has an instantaneous sense of the real world direction from his aircraft as apparently suspended within a spherical grid. The integrated display provides a presentation somewhat similar to existing flat screen separate instruments with an aircraft symbol lying at the center of the sphere with roll, pitch and heading scales displayed on this sphere. The sphere itself has one color such as blue above the horizon line and a different color such as brown below the horizon line.

Abstract: A filter system which may be configured either as a stopband (notch) or passband filter having controlled gain and low ripple throughout its stopband or passband. The system includes a filter network which is operative for splitting an input signal spectrum into a pair of complimentary spectrum components and a coupler for proportionately combining these spectrum components in accordance with a prescribed gain factor. The filter network may either comprise a pair of complimentary band reject and band pass filters connected to a common input terminal or a diplexer including identical filters coupled between a splitter and a combiner.

Abstract: A direct conversion receiver having a tri-phase architecture including three separate baseband signal channels. RF communications signals which are being tuned by the receiver are split into three equal and in-phase components which are mixed with three equal but substantially out-of-phase injection signals on frequency with the communications signal. The resulting baseband component signals are independently filtered and amplified on the three signal channels. The baseband components are then directed to a signal processing unit which corrects the baseband components for gain or phase mismatch errors between the signal channels based on the information carried by the three components and thereafter demodulates the signals in order to acquire the information carried by the RF communications signal. An automatic gain control system and a signal filtering system adapted for use with direct conversion receivers are also disclosed.

Abstract: The one-bit sigma-delta modulator with improved signal stability disclosed herein includes, in order, a first anti-aliasing filter (20), a chopper (22), a second anti-aliasing filter (30), and a one-bit modulator (32). The chopper (22) and one-bit modulator (32) are driven by a clock generator (38). The chopper (22) is introduced to provide a carrier upon which the signal may ride, thereby eliminating dc stability problems. The first anti-aliasing filter (20) eliminates aliasing from the chopper (22), and the second anti-aliasing filter (30) eliminates aliasing from the one-bit modulator (32). The second anti-aliasing filter (30) may be eliminated if the frequency of the chopper (22) is an exact integer submultiple of the sampling frequency of the one-bit modulator (32). This invention may drive a decimation filter (36), also driven by the clock generator (38), to provide a low cost analog-to-digital converter.

Abstract: This invention is for an accelerometer having a stack comprising both linearly responsive transducers and rotationally responsive transducers for measuring accelerations in the six degrees of freedom. Linear transducers such as lifters and tangenters can be combined in a stack with rotational transducers such as teeters and twisters which react to accelerations. Position sensors can be placed adjacent the transducers to sense their movement. When the position sensors detect a change, a current is applied to the transducer to return the transducer to its rest state. The current applied to return the transducer to its rest state is proportional to the acceleration experienced by the transducer, thereby providing a means to measure the acceleration on the transducer.

Abstract: A bearing assembly includes a bearing characterized by a gradated composition such that the bearing transitions from a metallic substrate such as high strength steel to an inner layer of silver, ceramics, or diamond-like material wherein the thermal coefficient of expansion as between the bearing and a rolling element or shaft is matched.

Abstract: The present invention provides a unique circuit and layout methods for improving upon series redundant circuits. A substitution device, comprising a pair of series connected N or P FETs for respective single FETs, can be further hardened or enhanced against cosmic rays, particles, etc. by spacing the P FETs a predetermined distance apart so that an ion or other particle cannot strike or affect both channels simultaneously, thus avoiding upset. When these devices are placed in cells (i.e., ASIC) in logic or the like circuits, the predetermined spacing is related to cell height. Also, alignment of the gates of the substitution device on a common axis minimizes the window of a satellite through which a particle could effectively strike the common gate axis possibly to upset both gates.

Abstract: The CAVITY REFERENCED ACOUSTO-OPTICAL LASER FREQUENCY STABILIZATION shown here locks the frequency of a laser 10 to that of a reference cavity 26. It frequency modulates the input 24 to the cavity 26 with an acouto-optical modulator 18 which operates on a sample 16 extracted from the output beam 14 of the laser 10 rather than on the output beam 14 itself. The cavity 26 can be tuned to any convenient frequency, and the operator is not limited to any specific reference absorption material. Since dithering is done on the sample 16 rather than on the output 14, no contamination of spectral purity takes place.

Abstract: An electromagnetic shield for components mounted to a printed circuit board includes an electrically conductive wall for interconnection to the printed circuit board for generally surrounding the components. The wall includes a top edge. The wall is disposed generally perpendicular to the printed circuit board. An electrically conductive cover for covering the area surrounded by the wall includes a top portion disposed generally parallel to the printed circuit board and a flange disposed generally parallel to the wall. The top portion of the cover includes a plurality of spaced apart springs disposed along the periphery of the cover for selectively engaging the top edge of the wall when the cover is positioned to enclose the area surrounded by the wall.

Abstract: An active matrix thin film transistor liquid crystal display having two thin film transistors for use in driving each of the liquid crystal pixels making up the matrix of the display. The first thin film transistor associated with each pixel is used in driving the pixel to capture data off of data lines in response to gate drive signals. The second thin film transistor associated with each pixel is used in compensating for the parasitic capacitances associated with the first thin film transistor and is driven by special compensating pulses.

Abstract: A high integrity data communication system for use with critical aviation information on a single transmission line which also utilizes code generators at the transmitter and receiver ends together with means for comparing the outputs of the code generators thereby authenticating the information at the receiver end.