Abstract: First and second coils (A, B) of optical fibers are disposed adjacent opposite ends of a housing (40). The housing defines an interior reservoir which contains a material (C) having substantial mass. Preferably, the material is a dense fluid such as mercury. Phase coherent light from a laser (10) is transmitted through the first and second optical fiber coils. The phase coherent light passing through the first and second coils is combined by an optical coupler (22). Under acceleration, the pressure to which the mercury subjects the two fiber optic coils varies by a pressure differential that is proportional to acceleration. The pressure differential causes a corresponding elongation and contraction of the optical fiber lengths which, in turn, causes a corresponding optical phase shift. The optical phase shift is detected interferometrically providing optical intensity changes.

Abstract: A silicon accelerometer employing the piezoresistive effect of single crystal silicon to measure the flexure of semiconductor beams supporting a semiconductor mass. In one embodiment a rectangular semiconductor center mass is supported at each corner by a semiconductor beam parallel to one side of the center mass and perpendicular to the adjacent beams, each of the beams having an implanted resistor at the stationary end thereof. The crystal planes and relative orientations of the resistors are selected so that two resistors always increase, and two always decrease their resistance by the same amount as the center mass is displaced, which allows them to be connected in a Wheatstone bridge having a symmetric differential output.

Abstract: An angular accelerometer utilizing a sensing element 10 comprising a strain member 18 and a crosswise torsion member 24, both substantially comprising flat beams 18 and 25, respectively. The strain member 18 is affixed at each end to the object whose angular acceleration is to be measured, the angular acceleration vector lying along the axis of the strain member 18. The torsion member 24 is formed with an end mass 26,26' at each end. The strain member 18 is formed from a material such as quartz whose elasticity changes in proportion to the torque it experiences. A high-frequency surface acoustic wave is sent along the strain member and the change in its frequency due to the torque in the strain member 18 is measured.

Abstract: The invention concerns method and apparatus to obtain accurate tracking of rotor blades, as for example helicopter rotor blades, despite the existence of conditions transiently altering rotor angular velocity.

Abstract: In a method of and an apparatus for detecting flaws inside articles, the flaw area for detection being subjected to ultrasonic pulses on which, after reaction with the flaw, a reference beam is superimposed, whereupon the resulting interference field is holographically detected, reconstructed and evaluated. This method can be applied to thin and sound-scattering materials with improved resolution and a description of the flaw configuration and detection of the deformation behavior of flaws. In the method, a load is applied to the flaw area under investigation and this area is subjected to ultrasonic pulses at least at two different times each corresponding to an extreme value of the loading, the ultrasonic pulses being short with respect to the load period and, after reaction with the flaw, reference pulses are superimposed on the ultrasonic pulses, whereupon the holograms of these ultrasonic applications are superimposed to give an interferogram which can be evaluated.

Abstract: A method of identifying and determining the size of particulates in a flowing fluid comprising detecting the portion of an ultrasonic pulse scattered from a particulate at a preselected angle, converting the results into density and elasticity-related values and comparing the values with measured or computed values for known particulates.

Abstract: A vibratory angular rate sensor system preferably consists of a Z-cut quartz plate forming a mounting frame with a rectangular opening. Within the opening are mounted two pairs of tines. Each pair of tines is parallel to each other, one pair forming the drive tines and the other pair the output tines. Each corresponding set of two tines is disposed along the same axis having a common stem or base. The tines are secured by four bridges integral with the frame and connected to the stem. The arrangement is such that the pair of input tines vibrates in opposition to each other, while the pair of output tines vibrates with one tine going up while the other moves downwardly. As a result, the angular rate sensors drive frequency and the structural torque frequency are unequal. Therefore large displacements of the stem are unnecessary.

Abstract: In an electromagnetic passage surveillance system, first and second receiver means are employed in mutually-spaced locations across a guarded portal to detect perturbations in an electromagnetic field extending across the portal, resulting from presence within the field of a high-permeability, low-coercivity marker. From the outputs of such receivers a sum signal and a difference signal are produced, and the high-order harmonics of the sum signal are emphasized to produce a first analysis signal while the low-order harmonics of the difference signal are emphasized to produce a second analysis signal. The ratio of the first analysis signal to the second, and thus the ratio of high-order to low-order harmonics, is used in logic and processing circuitry to dynamically vary the detection threshold by which the presence of a marker is determined.

Abstract: Apparatus employing ultrasonic pulse production at a transmit transducer at a known frequency is received at a receive transducer for sampling a liquid slurry of known composition, but unknown ratio, makeup of liquid, gas and fine, suspended particles. The transmission time is converted to digital form and an adjustable velocity-density slope factor is applied from empirical data to result in a readout voltage that directly relates to the density of the liquid slurry.

Abstract: In a structure utilizing a pair of accelerometers vibrating in a direction normal to their force sensing axes, a circuit utilizing voltage-to-frequency converters is utilized to convert the analog output signals from the accelerometers to digital signals representing the translational motion and the angular rate rotation of the structure.

Abstract: A rotational direction and angle detecting apparatus includes a stationary plate having first and second electrodes and a rotatable plate having third and fourth electrodes. Rectangular wave signals of opposite phases are applied to the first and second electrodes of the stationary plate. The third electrode of the rotatable plate has first and second auxiliary electrodes and the fourth electrode has third and fourth auxiliary electrodes. The first and second auxiliary electrodes and the third and fourth auxiliary electrodes are in opposed relation to the first and second electrodes respectively. With rotation of the rotatable plate, the capacitance values formed between the first and second auxiliary electrode and the first electrode and between the third and fourth auxiliary electrode and the second electrode are changed respectively.

Abstract: Portable measuring device, including a measuring instrument, a carrying strap fastened to the measuring instrument for hanging the measuring instrument around the neck, measuring lines electrically connected to the measuring instrument and passing through at least part of the carrying strap, measuring probes connected to the measuring lines, the measuring lines being in the form of flexible spiral cables between the carrying strap and the measuring probes, and at least one mounting disposed on the measuring instrument for fastening unused measuring probes hanging on the measuring lines.

Abstract: A thin-film strain gauge and a method for producing it are proposed; the strain gauge is advantageously capable of integration into a thin-film circuit. The strain gauge comprises an elastically deformable spring element in combination with at least one elongation-sensitive resistor. The resistor disposition (R1-R4), the low-impedance connections (L11-L42) between the various resistance regions and the associated connection tracks (L5-L8) are applied in a vacuum process, preferably by cathode sputtering. The low-impedance connections (L11-L42) and the connection tracks (L5-L8) are of material which, although different from the material making up the actual resistance region, still has approximately the same temperature coefficient of resistance, so as to preclude errors caused by temperature.

Abstract: A low-cost, two-axis rate and acceleration sensor utilizing piezoelectric generator elements affixed to the rotating housing of an inside-out synchronous motor. Signals generated by the piezoelectric bender elements are amplified, compensated, balanced, and converted to FM signals for transmission off the rotating assembly.

Abstract: A device for detecting the failure of a sensor which is installed on machine elements which are fitted with rotating parts, a reference signal being obtained from the output signal of the sensor, the reference signal being compared, in a comparator, with the output signal of the sensor, the output pulses from the comparator being employed to trigger a retriggerable one-shot multivibrator circuit. The absence of the output signal initiates an alarm and/or an adjustment of certain machine sub-systems. The arrangement can be employed for monitoring the most diverse types of sensor, for example for monitoring knock sensors in internal combustion engines.

Abstract: Leakage in a conduit system is detected by means of a fluid flow detector and evaluated by means of a control device on the basis of predetermined criteria. When the control device, which may include a microcomputer has received a signal from the flow detector indicating that fluid is flowing through the conduit system the control device operates an alarm device and/or closes the fluid supply by means of a valve, if the fluid flow is condidered to be caused by a leak or break in the conduit system evaluated on the basis of the time at which the flow takes place, the duration of the detected flow, the intensity of the detected flow, and/or information about whether the fluid drains of the conduit system are closed. The conduit system may, for example, be a conduit system for supply of water or gas to apartment houses and one-family houses, but may also form parts of industrial plants.

Abstract: An accelerometer includes a hinged proof mass constrained from movement by a beam resonator force transducer. To afford greater movement of the proof mass and greater latitude in positioning mechanical stops, one end of the force transducer is connected with the accelerometer base through a compliant mount. The other end of the force transducer is connected with the proof mass at the center of percussion of the proof mass. Adjacent surfaces of the proof mass and base provide squeeze film viscous gas damping. A pair of proof mass-force transducer systems are mounted on a carrier in opposite positions with the sensitive axes of the proof masses aligned and the proof mass hinge axes parallel and opposed to each other.

Abstract: A rate measuring instrument uses acoustic energy transmitted through a crystalline media (41) to sense rate. Acoustic energy travels along a path (1-31) within the crystalline media and impinges upon an output transducer (45) at an established point after being reflected a number of times from facets (47) of the crystalline media (41). Rate information is detected as a shift in the point of impingement of the greatest amount of acoustic energy upon the output transducer (45).

Abstract: The present invention provides an improved intrusion detection system of the type in which interruption of a beam of infrared energy transmitted from a transmitter to a receiver generates an alarm signal. The receiver includes a light source which remains unlighted when the transmitter and receiver are properly aligned but will be continuously lighted if either the beam is interrupted or the receiver and transmitter are not aligned. In one aspect of the invention, flasher circuitry in the receiver causes the light source to flash when the transmitted beam is only marginally aligned with the receiver. In another aspect of the invention, a lens in the receiver for focusing infrared radiation on a photodetector is movably mounted and accessible from the outside of the receiver to properly align the transmitted beam with the receiver without dismounting the receiver or requiring the use of any special alignment tools.

Abstract: An off-the-car wheel unbalance measuring system has a rotationally driven wheel mounting shaft supported in a pedestal together with a pair of force transducers mounted in the pedestal adjacent to and spaced along the shaft. The force transducers are coupled mechanically to the shaft and provide periodic electrical output signals indicative of unbalance forces transmitted through the shaft when the shaft is driven rotationally. The angular position of the shaft is monitored with respect to an angular reference position at a predetermined number of angular increments during each full revolution of the shaft. The transducer output signals are converted in electrical circuitry within the system to digital form, and a multiplication operation is performed on the digitized signals at each angular increment using sine and cosine representative factors corresponding to that particular angular increment.