Abstract: A system and method for measuring acceleration using a fiber optic accelerometer having a pair of fiber optic coils positioned around a deformable support structure. The support structure possesses a nominally cylindrical shape with the fiber optic coils being wound around opposite ends of the cylindrical support structure from each other. The support structure deforms from its nominally cylindrical shape to a conical shape in response to acceleration along a sensing axis. The changing shape of the support structure causes one of the fiber optic coils to expand while the other of the fiber optic coils contracts. The fiber optic coils are included in an interferometer such that acceleration along the sensing axis produces a phase difference between light signals propagating in the fiber optic coils resulting from their expansion and contraction.

Abstract: Method and apparatus for sensing the displacements of micromachined devices and sensors. The method is referred to as the enhanced modulated integrative differential optical sensing (EMIDOS). The target micromachined proof-mass, for which displacements are measured, includes a grid of slits. The émicromachined device is bonded to a CMOS chip containing a matching photodiodes array and their readout electronics. The grid is aligned with the photodiodes. An illumination source, such as an LED, is then mounted above the méicromachiend device.

Abstract: An apparatus for measuring exit velocity of a round from a muzzle of a gun barrel includes a first optical fiber having a first fiber optic Bragg grating (FBG) circumferentially attached to the gun barrel at the muzzle and a second FBG circumferentially attached to the gun barrel further from the muzzle than the first FBG; a coupler that receives one end of the first optical fiber; a light source connected by a second optical fiber to the coupler for supplying light to the first optical fiber; a third optical fiber comprising an FBG notch filter, the third optical fiber being connected to the coupler to receive light reflected from the first optical fiber; a notch filter mount attached to the gun barrel, the FBG notch filter being disposed in the notch filter mount; a photodetector connected to an end of the third optical fiber; and data processing electronics electrically connected to the photodetector.

Abstract: A method for delicately adjusting an orientation of features in completed micro-machined electromechanical sensor (MEMS) devices after initial formation and installation within the device packaging to trim one or more performance parameters of interest, including modulation, bias and other dynamic behaviors of the MEMS devices.

Abstract: A micromechanical component comprises a frame layer and an oscillating body which, with the aid of a suspension means, is supported in an opening penetrating the frame layer, in such a way that the oscillating body is adapted to be pivoted about an axis of oscillation vertically to the frame layer plane. At least one oscillating-body lateral surface, which extends substantially at right angles to the frame layer plane, is arranged in relation to at least one inner lateral surface of the opening in such a way that a capacitance formed therebetween is varied by an oscillation of the oscillating body in such a way that an oscillation of the oscillating body about the axis of oscillation can be generated by periodically varying a voltage applied between the frame layer and the oscillating body.

Abstract: An accelerometer is based upon the monolithic integration of a Fabry-Perot interferometer and a p+n silicon photosensor. Transmission of light through a Fabry-Perot etalon is exponentially sensitive to small displacements in a movable mirror due to an applied accelerating force. The photosensor converts this displacement into an electrical signal as well as provides for additional amplification. Because the interferometer and photosensor are monolithically integrated on a silicon substrate, the combination is compact and has minimal parasitic elements, thereby reducing the accelerometer's noise level and increasing its signal-to-noise ratio (SNR).

Abstract: A microelectricalmechanical system (MEMS) digital isolator may be created in which an actuator such as an electrostatic motor drives a beam against a predefined force set, for example, by another electrostatic motor. When the threshold of the opposing force is overcome, motion of the beam may be sensed by a sensor also attached to the beam. The beam itself is electrically isolated between the locations of the actuator and the sensor. The structure may be incorporated into integrated circuits to provide on-chip isolation.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Abstract: A multi-axis accelerometer is disclosed comprising at least one optical sensor for generating a sensor signal in response to light illuminating the optical sensor, a mask positioned over the optical sensor for covering a first area of the optical sensor, at least one spring, and a mass suspended above the optical sensor by the spring. The mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask. When the multi-axis accelerometer accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration.

Abstract: A method for measuring acceleration uses an accelerometer apparatus having an optically transparent, stress-birefringent material, a source of polarized light positioned to direct a polarized beam of light into the optically transparent, stress-birefringent material, and a detector system positioned to detect an output beam from the optically transparent, stress-birefringent material. The accelerometer apparatus is accelerated, and the acceleration of the accelerometer apparatus is simultaneously determined from a measurement of stress-induced optical birefringence in the optically transparent, stress-birefringent material.

Abstract: For sensing the relative movements of an object a force sensing unit (15) comprises a stationary supporting means (6) and a cap (150) located movable relative to said supporting means as well as a force/moment sensor (1) for sensing the three possible translational and three possible rotational movements of the cap relative to said supporting means.

Abstract: An improvement to an optical accelerometer based upon the monolithic integration of a Fabry-Perot interferometer and a p+n silicon photosensor includes using one or more pairs of optical accelerometers wherein each pair provides for greater accelerometer sensitivity than a single independent accelerometer, and allows for a reduction in common mode noise due to amplitude and phase difference variations of the utilized light source as well as supply voltage. The differential approach of the invention provides for the biasing of the optical accelerometers such that their output signals are 180 degrees out of phase with each other.

Abstract: A micro electromechanical switch for detecting acceleration or deceleration includes a rectangular planar mass of, for example, etched silicon suspended on a pair of beams from an anchor located in the same silicon base. Motion in a plane of movement caused by acceleration or deceleration is detected by a pair of photodiodes and a light emitting diode located on opposite sides of the planar mass or shutter so that when the shutter moves the interruption of the light is sensed and thus acceleration or deceleration is indicated.

Abstract: An accelerometer signal processor is disclosed comprising a sensor for generating A, B, C and D sensor signals in response to a sensor excitation. Variable oscillators convert the sensor signals into oscillating signals, and the oscillating signals up-count and down-count counters. The outputs of the counters represent a linear acceleration along at least two axes, as well as a rotational acceleration.

Abstract: An accelerometer facilitates optical, interferometric measurement of acceleration. The device includes a proof mass having a first set of spaced-apart, elongated fingers projecting therefrom, and a stationary housing or substrate comprising a second set of similarly arranged projecting fingers. A spring connects the proof mass to the substrate such that, in a rest configuration, the first and second set of fingers interdigitate. When the structure is accelerated, the substrate fingers remain stationary, while the alternating fingers of the proof mass are displaced therefrom. This creates a phase-sensitive diffraction grating which, when illuminated, facilitates determination of the relative displacement between the sets of fingers by measuring the intensity of the diffracted modes. This displacement, in turn, indicates the acceleration experienced by the accelerometer structure.

Abstract: An apparatus for demonstrating changes in motion with respect to time. Two arrays of equally spaced photoresistors and light-emitting diodes are placed on two parallel straight line arrays. Rails upon which an object moves are placed parallel to the arrays. A laser is attached to the object. At any moment of time during the motion of the object, the laser illuminates one or two adjacent photoresistors. Each photoresistor in a line of elements is connected to a first input of a logic AND gate, to whose second input clock pulses are conducted and whose output is connected through a logic flip-flop element to the light-emitting diode. The apparatus provides for demonstration of a motion development in time by conveying a visual demonstration of path sections or intervals traversed by the object in equal time intervals to thereby make possible a picture of whether the motion is steady or accelerated.

Abstract: A fiber optic seismic sensor includes a central support assembly formed of a metal such as aluminum. A support plate has an inner portion retained within the central support assembly and an outer portion that extends beyond the central support assembly. A pair of hollow cylindrical substrates are mounted in axial alignment on opposite sides of the outer portion of the support plate with the central support assembly extending through the centers of the substrates. The central support assembly comprises a first central support member having a cavity in one end, and a second central support member having a projection extending therefrom and arranged to be received within the cavity in the first central support member. The support plate includes a passage arranged to receive the projection such that the inner portion of the support plate is retained between the first and second central support members.

Abstract: A fiber optic particle motion accelerometer has a housing with a mid-section mounted therein such that the mid-section flexes in response to acceleration along a sensing axis. A proof mass is mounted to an outer edge of the mid-section. A first spiral-wound optical fiber coil is mounted to a first side of the mid-section and a second spiral-wound optical fiber coil is mounted to a second side of the mid-section. A first hinge is formed in the mid-section adjacent the mounting of the mid-section in the housing, and a second hinge is formed in the mid-section between the proof mass and the first and second fiber optic coils. The optical fiber coils are included in an interferometer such that acceleration along the sensing axis produces a phase difference between optical signals propagating in the optical fiber coils.

Abstract: An encoder operates in accordance with the transparent scanning principle. The encoder includes a rotating shaft, a partial disk connected nonrotatably concentrically with the shaft, an illuminating unit, and a scanning receiver located axially in front of the end of the shaft. The illuminating unit is connected nonrotatably centrally with the shaft and rotates with the shaft on the side of a partial disk that faces away from the scanning receiver. The scanning receiver includes a monolithic photoreceiver array which is formed with photosensitive sensor areas associated with an angular displacement of the partial disk.

Abstract: A micro-electromechanical optical inertial sensing device comprises a CMOS chip (3), comprising at least one integrated photodiode (6) and analog electronics; an elastically suspended proof mass (1); and a light source (4). A light beam from the light source casts a partial shadow of the proof mass over the photodiode when the proof mass is at rest. When subjected to an inertial movement, the proof mass swings causing the partial shadow to shift and modulate the illumination of the photodiode. An output current signal from the photodiode is processed by the analog electronics to generate measurement results.

Abstract: A fiber optic displacement sensor includes a flexural disk assembly affixed to mounting post that extends from a support base. The flexural disk assembly is mounted in a housing. Spiral wound optical fiber coils are mounted on opposite sides of the flexural disk with optical fiber leads extending from both the inner and outer diameters of the optical fiber coils. Optical signals output from the coils are coupled together to form an interferometer. An inertia ring connected to the periphery of the flexural disk. has a plurality of peripheral slots therein for routing the optical fiber leads from the first and second optical fiber coils to other components in the housing. The inertia ring has curved side edges formed such that the optical fiber leads may be spiral wound thereon between the first and second coils and the peripheral slots to prevent damage to the optical fiber leads from sharp bends.

Abstract: Methods and apparatus for detecting particular frequencies of acoustic vibration utilize an electrostatically-tunable beam element having a stress-sensitive coating and means for providing electrostatic force to controllably deflect the beam element thereby changing its stiffness and its resonance frequency. It is then determined from the response of the electrostatically-tunable beam element to the acoustical vibration to which the beam is exposed whether or not a particular frequency or frequencies of acoustic vibration are detected.

Abstract: A vehicle acceleration and attitude sensor is provided, having use as a vehicle collision sensor for activation of air bags and the like, and as well for detecting an unsafe angle or attitude of the vehicle. A compressible carrier medium of light or other wave energy, such as translucent foam, is coupled with a light or other wave energy source and a receiver. An inertial mass, which may consist of the carrier medium itself, is in contact with the carrier medium and operates to compress the carrier medium when the apparatus is either accelerated or tilted beyond a predetermined amount. A signal coupler and processor are associated with the energy source and receiver. The apparatus operates on the principle whereby compression of a scattering medium or an integrating cavity, within the region surrounding a light or other wave energy source, will increase the intensity of the wave energy. This increased intensity is translated into a measurement of the acceleration or tilt experienced by the sensor.

Abstract: A gravity-type horizontal shift sensing apparatus being mounted on and moved along with an object for efficiently sensing and measuring any difference in angle of inclination of the object when the object moves. The apparatus includes two intersected rocking arms rotatably disposed between close-up inner cover and inner seat, and a weight suspended from the rocking arms. The rocking arm each is provided at one end outside the inner cover and the inner seat with a toothed wheel and an optical wheel associated with the toothed wheel. The toothed wheel meshes with a gear sideward projected from a wheel mounted to one side of the rocking arm. The wheel each also has an optical wheel associated therewith. Outer peripheries of the optical wheels on the rocking arms and the wheels respectively pass between two sensing elements mounted at two sides of recesses formed on the circuit board.

Abstract: Secondary circuit board which carries an acceleration sensor is mounted upon a primary circuit board in an anti-lock brake system control unit. The secondary circuit board is mounted at an angle to the primary circuit board and the acceleration sensor is mounted at an angle relative to the secondary circuit board to align a sensing element contained in the acceleration sensor perpendicular to a direction of vehicle travel.

Abstract: A vehicle rollover sensor (10) includes an optical transmitter (80) for providing a light beam (86) extending in a first direction (36) and an optical receiver (90) for receiving the light beam. A movable member (40) when in a first orientation enables the light beam (86) from the optical transmitter (80) to be directed to the optical receiver (90). The movable member (40) when in a second orientation prevents at least a part of the light beam (86) from being directed to the optical receiver (90). The movable member (40) is supported on the vehicle for movement between the first and second orientations in a direction transverse to the first direction (36), in response to rolling movement of the vehicle of a predetermined amount relative to the first direction. An inertia mass (60) is connected with the movable member (40) to maintain the movable member in a predetermined orientation relative to the ground surface on which the vehicle is disposed.

Abstract: An accelerometer has a main body in combination with one or more Bragg grating sensors respectively arranged along one or more axes. The main body has a mass that responds to an acceleration, for providing a force having a component in one or more axes. The Bragg grating sensor means responds to the force, and further responds to an optical signal, for providing a Bragg grating sensor signal containing information about the acceleration respectively in one or more axes. The one or more axes may include orthogonal axes such as the X, Y and Z Euclidian axes. In one embodiment, the main body includes a proof mass and a pair of flexure disks, each having an inner ring, an outer ring, and radial splines connecting the inner ring and the outer ring. The proof mass is slidably arranged between the flexure disks. The Bragg grating means has an optical fiber and a Bragg grating sensor arranged therein. A first end of the Bragg grating sensor is fixedly coupled by a first ferrule to the proof mass.