Abstract: Aspects of the present disclosure are directed to alternative repeater design(s) that advantageously improve signal-to-noise of distributed acoustic sensing (DAS) systems using coherent detection of Rayleigh backscatter in multi-span links including inline amplification that may be employed—for example—in undersea submarine systems. The repeater designs incorporate Rayleigh combine units (RCU) and Rayleigh drop units (RDU) to reduce Rayleigh backscatter loss as Rayleigh signal(s) is/are routed to a link that propagates the backscatter signal in an opposite direction relative to interrogation pulse(s).

Abstract: An apparatus is described, the apparatus including a case, a display assembly, a chassis connected to the display assembly, a suspension component between the display assembly and the case, wherein the suspension component is configured to allow the display assembly to move relative to the case, at least one vibrating element configured to actuate the chassis to move the display assembly relative to the case to generate at least one of acoustic waves or haptic/tactile effect, and an internal cavity below the display, wherein electronic components of the apparatus are located at the internal cavity.

Abstract: An acceleration measuring device includes a housing with an inner cavity, a reference substance disposed in the inner cavity, an elastic supporting member connected between the bottom portion of the inner cavity and the reference substance, a light source secured to a side of the reference substance, a lens secured to the reference substance that is positioned at a side of the light source away from the reference substance, an image sensor at a top portion of the inner cavity and located at a side of the lens away from the reference substance for receiving light emitted by the light source and scattered by the lens, and a processor configured to calculate displacement information of the reference substance in a vertical direction according to light received by the image sensor, and calculate an acceleration of the reference substance according to the displacement information.

Abstract: There is provided a medical observation device, including: an observation unit configured to perform magnified observation of a surgical site; a vibration sensor that detects a vibration of the observation unit; a support unit that supports the observation unit; and a control unit that conducts an image shake correction that corrects a shake in an image observed by the observation unit, based on a detection value from the vibration sensor.

Abstract: An apparatus is described, the apparatus including a case, a display assembly, a chassis connected to the display assembly, a suspension component between the display assembly and the case, wherein the suspension component is configured to allow the display assembly to move relative to the case, at least one vibrating element configured to actuate the chassis to move the display assembly relative to the case to generate at least one of acoustic waves or haptic/tactile effect, and an internal cavity below the display, wherein electronic components of the apparatus are located at the internal cavity.

Abstract: An unbalance detection device for detecting unbalance of a rotor of a turbo-cartridge which includes the rotor including a turbine wheel and a compressor wheel coupled via a rotational shaft and a bearing housing accommodating a bearing which supports the rotor rotatably, includes: a turbine-side housing member accommodating the turbine wheel; a compressor-side housing member accommodating the compressor wheel; a support mechanism configured to nip and support the turbo-cartridge from both sides by pressing at least one of the turbine-side housing member or the compressor-side housing member toward the turbo-cartridge; a vibration insulator interposed in each of a gap between the turbine-side housing member and the turbo-cartridge and a gap between the compressor-side housing member and the turbo-cartridge; and a vibration sensor installed so as to be contactable with the bearing housing, the vibration sensor being capable of detecting vibration upon rotation of the rotor.

Abstract: A fiber-based accelerometer (FAC) detector includes a base; first and second flexures mechanically coupled to the base; first and second masses mechanically coupled to the first and second flexures, respectively; and a fiber Bragg grating (FBG) fiber mechanically coupled to the first and second masses, wherein the first and second flexures and the first and second masses are configured to move in response to a force and/or acceleration acting upon the first and second masses to produce a compression or expansion of the first FBG fiber.

Abstract: A light attachable to an outside surface includes a base, a housing and an electronic assembly. The housing has an outer surface, an inner surface and a mating surface. The two are joined to define a substantially fluid tight cavity. The housing has a lens portion and a charging portion; each are at least one of transparent and translucent. The electronic assembly is positioned within the housing, and includes at least one LED light, control circuitry coupled to the LED light, a solar panel and a battery coupled to the control circuitry. The solar panel is configured to charge the battery. The battery is coupled to the LED light under the control of the control circuitry. A plurality of sensors provide data to the control circuitry to direct the LED light in one of an on position and an off position.

Abstract: The invention concerns a folded pendulum, comprising: a support (F); a test mass (PM); a simple pendulum (SP); an inverted pendulum (IP); the simple pendulum and the inverted pendulum being connected at one of their ends to the test mass (PM) and at the other end to the support (F) by means of 4 corresponding joint systems (G), the test mass being not connected to the support (F) and being therefore free to oscillate, each joint system (G) relevant to the simple pendulum (PS) comprising one or more joints in tension, the folded pendulum being characterized in that: each of the joint systems (G) relevant to the inverted pendulum (IP) comprises one or more joints in compression. The invention further concern a seismic sensor utilizing the folded pendulum according to the invention.

Abstract: A sensor includes a housing adapted to be secured to a component within a system to be monitored by the sensor, an optical fiber, and a membrane spring assembly. The optical fiber includes a sensing portion containing a fiber Bragg grating that is able to undergo expansion and contraction resulting from movement of the optical fiber at a second location relative to a first location. The membrane spring assembly includes a membrane disc, wherein movement of a central portion thereof causes corresponding displacement of the optical fiber at the second location to cause expansion and contraction of the sensing portion of the optical fiber containing the fiber Bragg grating, which expansion and contraction effects a change in a light wavelength reflected by the fiber Bragg grating. The light wavelength reflected by the fiber Bragg grating can be used to measure movement of the central portion of the membrane disc.

Abstract: A device for detecting seismic acceleration includes a proof mass; a base for providing a sensor acceleration, relative to the proof mass, based on the seismic acceleration; and an optical fiber portion operatively connected between the proof mass and the base for providing a fiber tension based on the sensor acceleration. A fiber Fabry-Perot interferometer (FFPI) in the optical fiber portion provides an optical characteristic representative of the fiber tension. A compensator applies a compensating tension to the FFPI to compensate for a change of the optical characteristic due to a temperature change of the FFPI.

Abstract: The transparent photodetector includes a substrate; a waveguide on the substrate; a displaceable structure that can be displaced with respect to the substrate, the displaceable structure in proximity to the waveguide; and a silicon nanowire array suspended with respect to the substrate and mechanically linked to the displaceable structure, the silicon nanowire array comprising a plurality of silicon nanowires having piezoresistance. In operation, a light source propagating through the waveguide results in an optical force on the displaceable structure which further results in a strain on the nanowires to cause a change in electrical resistance of the nanowires. The substrate may be a semiconductor on insulator substrate.

Abstract: An acoustic-wave sensor (10) is constructed by a membrane (11) adapted to be displaced by an acoustic wave, a first waveguide (16a) for transmitting light therein, an optical coupling part (15) to which the light transmitted through the first waveguide (16a) is adapted to be optically coupled, and a second waveguide (16b) through which the light coupled from the optical coupling part (15) transmits. When the membrane (11) is displaced by its reception of the acoustic wave, at least one of an optical coupling coefficient between the first waveguide (16a) and the optical resonator (15) and an optical coupling coefficient between the second waveguide (16b) and the optical resonator (15) is changed to output a corresponding optical signal.

Abstract: A tri-axis accelerometer for use in seismic surveying is provided. The accelerometer comprises at least three fiber optic accelerometer elements which have respective fiber sensor coils, and which are characteristic in that the fiber sensor coils are coiled about a common coiling axis and at least one of the accelerometer elements is a slant angle accelerometer element. A corresponding method of manufacturing a tri-axis fiber optic accelerometer is also disclosed. A fiber optic tri-axis accelerometer for sensing acceleration in three directions is also provided, which comprises a first, a second, and a third sensor base, each base including a first, a second, and a third fixed element, respectively, and a first, a second, and a third movable element, respectively, each pair of fixed and movable elements carrying a fiber sensing coil.

Abstract: Methods, structures, devices and systems are disclosed for implementing optical seismometers that detect seismic information based on optical interferometry. In one aspect, a device includes a first retroreflector attached to a mass of a seismometer, a second retroreflector attached to a member of a frame of the seismometer, the frame structured to suspend the mass, and optical components attached to the member of the frame and configured with the first and second retroreflectors to form an interferometer, in which a change in position of the mass is identified by detecting by a change in an optical path of a light beam generated by a light energy source transmitted to the interferometer.

Abstract: An electronic scale having a measuring sensor (1 . . . 16), a digital signal processing unit (18), a digital display (19) and an inclinometer (40). The inclinometer derives a signal for the tilt of the scale from the difference of at least two signals. The digital signal processing unit (18) is provided with an additional circuit component or program routine that adds the two signals and, by way of this cumulative signal, corrects the vibration-distorted signal of the measuring sensor (1 . . . 16). A plurality of inclinometers enables the simultaneous detection of momentary gravitational acceleration. For example, in an electric bubble level, the gas bubble moves out of place when tilted and the diameter of the gas bubble changes when the gravitational acceleration changes. The scale thus provides an additional signal for correcting the influence of disturbances with minimum complexity.

Abstract: The present invention relates to an optic seismic MEMS sensor. More specifically, a proof mass is supported by a frame having supporting beams. The proof mass is positioned within the frame and has a hinged attachment to the beams. The proof mass has a sensor gap having a first reflector and a second reflector positioned at opposing ends of the sensor gap. An optical fiber injects light into the sensor gap and light is reflected to determine seismic movement of the proof mass with respect to the frame. Stops are provided for limiting the movement of the proof mass to minimize strain on the attachment of the beams and the proof mass.

Abstract: A sensor and a method for sensing a change in mass of a reflective microbeam in a sensor, the sensor having a reflective layer disposed on a substrate and spaced apart from the reflective microbeam. The microbeam receives amplitude modulated laser energy at a first wavelength and is photothermally excited into resonance at the frequency of amplitude modulation, the reflective microbridge and the reflective layer receive optical energy at a second wavelength and reflect the optical energy toward a receiver. A change in reflectivity of the microbeam at different frequencies is determined. A change in reflectivity indicates a change in resonant frequency of the microbeam. Mass of the microbeam changes when a chemoselective material on the microbeam sorbs a target chemical.

Abstract: An optical characteristic measuring apparatus of the invention is configured in such a manner that a specular reflection light component in reflection light from an object to be measured is received, and shake of the apparatus is detected based on the amount of the received light. The optical characteristic measuring apparatus having the above arrangement enables to precisely measure an optical characteristic of the object to be measured, without the need of providing a mechanical switch or a like device, and without depending on the shape of the object to be measured.

Abstract: A sensor having a mass that moves relative to a structure is disclosed. A spring mechanism applies a restoring force to the mass when the mass moves from an equilibrium position with respect to the structure. A first code scale is attached to the mass and viewed by a first imaging system that is fixed with respect to the structure. The first imaging system forms images of the first code scale that are used by a controller to provide an indication of the relative position of the mass with respect to the structure. The mass can be located in a sealed chamber in the structure that has a transparent liquid through which the mass moves. The first imaging can view the first code scale from outside the chamber through a transparent window in the chamber.

Abstract: The present invention relates to an optic seismic MEMS sensor. More specifically, a proof mass is supported by a frame having supporting beams. The proof mass is positioned within the frame and has a hinged attachment to the beams. The proof mass has a sensor gap having a first reflector and a second reflector positioned at opposing ends of the sensor gap. An optical fiber injects light into the sensor gap and light is reflected to determine seismic movement of the proof mass with respect to the frame. Stops are provided for limiting the movement of the proof mass to minimize strain on the attachment of the beams and the proof mass.

Abstract: An obstacle sensor includes: a supersonic sensor for detecting an obstacle in a first range, the supersonic sensor including a substrate, a transmission device and a reception device disposed on the substrate; a detection element for detecting the obstacle in a second range; and a case. The reception device includes multiple reception elements. At least a part of the first range of the supersonic sensor is different from the second range of the detection element. The supersonic sensor and the detection element are disposed in the case.

Abstract: A vibration measuring and monitoring system (100) for an object (20) includes a laser unit (11), a laser sensor unit (12), and a processor (15). The laser unit is used for emitting a laser beam (13). The laser sensor unit is used for receiving the laser beam, and the laser sensor detects a light intensity signal of the laser beam. The processor is used for processing the light intensity signal of the laser beam. The object is partially disposed between the laser unit and the laser sensor unit. The laser beam crosses the object and is received by the laser sensor unit. The processor obtains a vibration signal by processing the light intensity signal.

Abstract: A system for sensing vibration of a machine is provided. A light source directs a beam of light toward a light receiving system adapted to receive at least a portion of the beam of light. A light modulating system modulates the light beam received by the light receiving system so as to correspond to vibration of the machine. A processing system operatively coupled to the light receiving system processes data received from the light receiving system to facilitate determining vibration of the machine.

Abstract: The present invention provides an attitude sensing device and method for determining an attitude of a reference axis of a package containing a fiber optic sensor sensor. The attitude sensing device comprises an electro-mechanical attitude sensor for generating an electrical signal indicative of the attitude sensor, and converter logic for converting the electrical signal into a stimulus signal. A local power source is preferably provided for the electro-mechanical attitude sensor in the converter logic. The stimulus signal is such that the fiber optical sensor is responsive to the stimulus signal to cause a variation in at least one predetermined property of an optical signal transmitted through the fiber optic sensor, the attitude of the reference axis being determinable from the variation of the predetermined property.

Abstract: An apparatus for demonstrating, investigating and observing Brownian motion and temperature of a medium, such as gas or liquid, uses a small particle which is diamagnetically suspended in the medium. The tiny magnetized particle having a known mass is levitated using a diamagnetic technique, and the displacement of the particle over time is observable, which can be used to determine a temperature of the medium. Optionally, a second particle is suspended in a vacuum but mechanically connected to the same apparatus as the first enclosure with the first particle, thereby allowing observation and measurement of non-Brownian movement of the structure, and allowing more precise observation of Brownian movement effects on the first suspended particle.

Abstract: The present invention provides a configuration where all optical parts of a monitoring system are contained within a seal and within the generator itself. Non-optical preamplifier functions may also be placed within the seal. In this configuration there is an electrical rather than optical feed-through at the generator wall, which is hermetically sealed, unlike a fiber optic feed-through. The fiber optic light source and detector for each sensor is located in the seal on the generator side of the hermetic electrical feed-through. Electrical power and the sensor's converted electrical vibration signals pass through the electrical feed-through to preamplifier circuitry on the outside of the seal where direct electrical connection is then made to a main chassis unit.

Abstract: A mass is levitated with respect to a base, at least one of which is comprised of a diamagnetic material, with the levitated mass also having a permanent magnetic property. A second permanent magnet is optionally configured such that it attracts the levitation mass away from the base to overcome gravitational force on the mass, thereby suspending the mass over the surface of the base. The mass is contained in a nonmagnetic, non-shielding and optionally optically-transparent housing so as to limit its excursion within a range of levitation positions. A position measurement means such as a laser interferometer, capacitance detector, or pickup coil is configured to measure positional deviations of the mass in response to incident pressure wave, the output of which being an electronic signal representing the pressure wave.

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: The invention relates to a steam turbine (3) comprising an optical measuring system (60) for measuring a moving blade vibration. A transmitter (55) produces a light beam (61) which strikes the moving blades (27, 29, 31, 33) and is reflected by these into a receiver (57). By providing that the transmitter (55) is separated from the receiver (56), the invention achieves a measuring angle that actually reduces the scattered light effect of the steam enough to enable reliable optical measurements of the blades vibration. The invention also relates to a method for measuring the vibration of a moving blade (33) in a flow channel (19, 21, 23, 25) of a steam turbine (3).

Abstract: A vibration measuring apparatus (10) inlcudes an accelerometer (12) which is contained within a surface micromachined integrated chip, and signal processing means including a high pass filter (14), a low pass filter (16) and an integrator (18).

Abstract: A sensor for detecting acoustic energy includes a microstructure tuned to a predetermined acoustic frequency and a device for detecting movement of the microstructure. A display device is operatively linked to the movement detecting device. When acoustic energy strikes the acoustic sensor, acoustic energy having a predetermined frequency moves the microstructure, where the movement is detected by the movement detecting device.

Abstract: This invention is pertaining to multi purpose shock sensor comprising three conductive plates arranged in 3 layers in parallel which make 2 variable capacitors connected in series. Two outer plates are firmly attached to a supporting insulating material and the center plate is located between the 2 outer plates and arranged as movable by resilient element toward either side of the outer plate depending on the direction of the impact felt on the shock sensor causing changes of the capacitance values of the both capacitors. If the 2 capacitors are connected across a voltage source through a resistor, the voltage is charged across the 2 capacitors and their charged values are inversely proportional to their capacitance values. Moving the center plate due to a shock causes changes on both capacitance values, which change voltages across the capacitors, and the changed voltage can be used to activate an object.

Abstract: An elastic-wave monitoring device includes an optical system which is arranged so that a circularly polarized light from a light source is incident to a measured object and a light beam from the measured object passes through a polarizing filter to a photodetector. A detection unit detects periodic fluctuation components of an output signal of the photodetector. In the elastic-wave monitoring device, the polarizing filter is arranged to have a polarization transmission axis directed to one of directions of principal axes of an ellipse formed by intersections of an index ellipsoid of the measured object and a plane perpendicular to an incidence direction of the light beam and passing through an origin of the index ellipsoid.

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: At least one parameter of at least one fluid in a pipe 12 is measured using a spatial array of acoustic pressure sensors 14,16,18 placed at predetermined axial locations x1,x2,x3 along the pipe 12. The pressure sensors 14,16,18 provide acoustic pressure signals P1(t), P2(t), P3(t) on lines 20,22,24 which are provided to signal processing logic 60 which determines the speed of sound amix of the fluid (or mixture) in the pipe 12 using acoustic spatial array signal processing techniques with the direction of propagation of the acoustic signals along the longitudinal axis of the pipe 12. Numerous spatial array processing techniques may be employed to determined the speed of sound amix. The speed of sound amix is provided to logic 48 which calculates the percent composition of the mixture, e.g., water fraction, or any other parameter of the mixture or fluid which is related to the sound speed amix. The logic 60 may also determine the Mach number Mx of the fluid.

Abstract: The present invention discloses a vibration measurement method and apparatus using a self-mixing type laser Doppler vibration meter. The vibration measurement method according to the present invention comprises: an inclination value calculation step S3 for calculating an ascending inclination and a descending inclination for each beat wave; and a turning point identification step S4 for identifying the turning point of a vibrating object according to the inclination change along the time axis.

Abstract: A method for measuring the ripeness and the texture of a fruit, the method comprising a step for applying a vibration having sequentially hanging frequencies to a fruit to be measured, a step for measuring the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, a step for measuring the weight of the fruit, a step for finding the transfer functional characteristic of the fruit by performing frequency analysis based on the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, and computing the secondary resonance frequency f0 (i.e.

Abstract: A geophone includes an optical element capable of changing its refractive index and path length in response to acceleration of the geophone. The sensor component comprises a mass mounted on a fulcrum for rotational movement against the force of a biasing member. An optical fiber is stretched between the casing of the sensor and an extension of the mass, such that rotational movement of the mass about the fulcrum varies the tension in the fiber. Varying the tension in the fiber varies the optical path length and index of refraction of the fiber, and these variations may be detected as a seismic signal. A first set of magnets dampens the vibratory movement of the mass, and a second set of magnets reduces the frequency of the movement of the mass.

Abstract: The investigation, development and application of a laser-based ultrasonic inspection system to the problems of evaluating polymer/graphite composite materials has been realized. The use of lasers to generate and detect ultrasonic waveforms in materials provides a means to detect material properties remotely. The study consisted of three main aspects: 1) A confocal Fabry-Perot (CFP) based system has been devolved which uses light reflected from the CFP interferometer to derive the ultrasonic signal. This allows higher frequency components of the detected waveforms to be discerned when compared to a CFP-based system using light transmitted through the CFP interferometer. 2) Thermoelastic and ablative laser generation of acoustic pulses in polymer/graphite composite materials has been investigated. Thermoelastic generation of ultrasound occurs when thermal energy deposited by a pulsed laser creates a localized expansion in the material.

Abstract: An apparatus and method of non-invasive measurement of a chosen region (4) within a body (2), using the transmission of an ultrasonic pulse and the measurement of back scattered optical radiation which has been modulated by the ultrasonic pulse at the region of interest. There may be two or more ultrasonic transmitters (10, 14) to allow control of the vibration of the ultrasonic pulses at the region (4) of interest.

Abstract: The invention concerns a faseroptic load sensor with a support structure and at least one interference structure shaped like a wire, on which at least one optical fiber is displayed. The optical fiber is cleared through a wireshaped interference structure at intervals from the support structure so that a large number of bent spots occur. An additional pressure load on the optical fiber vertical to the support structure then causes changes in the bending radius of each bend spot.

Abstract: An optical vibration sensor includes a built-in blade provided with a system for reflecting light, a system for directing light onto the reflecting system, system for collecting the light reflected by the reflecting system and a system for analyzing the intensity and/or the frequency and/or the phase of the reflected light. The blade forms an integral part of an appropriately cut block.

Abstract: A resonant beam or cantilever is implemented in single crystal silicon or polysilicon. Adjacent the end of the cantilever is an electrode capable of receiving a variable voltage. The cantilever has a natural mechanical resonant frequency when vibrated, and the varying electrostatic field resulting from the variation of applied voltage to the electrode is used to alter the natural restoring force of the cantilever so that a chosen vibration frequency of the cantilever can be achieved. Such vibrating cantilever can be used as the bases for a voltage control oscillator.

Abstract: An apparatus for measuring kinematic errors in power transmission mechanisms with an input shaft and an output shaft. The apparatus comprises a pair of laser doppler velocimeters (LDV's) (16,34). Each generates a laser beam split into two equal-intensity parallel beams which are projected so as to strike a shaft while the shaft rotates. The shaft produces reflected beams having a frequency which is shifted from that of the incident beams, thereby producing returning beams which are heterodyne. A measuring (20,38) channel is in communication with each LDV. An attenuator (24) is in communication with one of the measuring channels (20) for decreasing the amplitude of a signal generated by the measuring channel (20). A summing and integrating amplifier (28) is connected to the attenuator, the amplifier generating a signal indicative of kinematic error in the gear mechanism.

Abstract: An acceleration sensor for measuring accelerations in at least one direction, the sensor including: a plate-like seismic mass which responds to accelerations, is disposed within a fixed frame and is movably fastened to the frame by at least one web extending between the mass and the frame. A first light waveguide for receiving a light beam from a light source, is disposed on a surface of the seismic mass so that a light beam passing therethrough is deflected as a function of movement of the seismic mass, and a second light waveguide is disposed on a surface of the fixed frame opposite an end of the first light waveguide for coupling the light beam to a detector for detecting deflections of the light beam as a measure of detected acceleration by the sensor. Preferably, the first and second light waveguides comprise planar light conductor paths or strips and the mass, webs and frame are all formed of silicon.

Abstract: An apparatus for investigating a sample with ultrasound has a probe head formed by a casing, a transducer element of piezoelectric plastics material, and a source for applying a high frequency pulse to the sample. The source is preferably one end of an optical fibre, which fibre extends to a laser remote from the probe head. The transducer element is connected to the sample by an acoustic coupling medium, e.g. water. Thus, the probe head can be moved relative to the sample, and a compact, but efficient, structure is achieved.

Abstract: An optical lever acoustic and ultrasound sensor with increased sensitivity using an optical amplification means to amplify the motion of an incident acoustic wave and convert it to an electric signal for image processing. Three approaches to the optical amplification are disclosed. In the first approach, the vibrating mirror is part of a cantilever that increases the angular deflection of the incident light beam. In the second approach, a second, stationary mirror is positioned approximately parallel to the vibrating mirror surface. The reflected light beam is reflected back onto the vibrating mirror, and picks up a another increment of the acoustic signal with each reflection. In the third approach, the effective moment of the optical lever is increased within a small volume by the use of two stationary mirrors to increase the path length from the vibrating mirror to the position-sensitive detector.

Abstract: An accelerometer or seismometer has a pair of flat spirals of optical fiber and has one or more elastic disks bearing a mass and supported for flexure. Each spiral is fixedly attached to a corresponding disk side so that disk flexure lengthens a spiral on one disk side and shortens a spiral on an oppositely facing disk side, the spirals being connected as legs of a fiber optic interferometer so that the interferometer provides an output corresponding to the flexure. A pair of the disks may be mounted oppositely of a sealed body with a pair of the spirals arranged to minimize the effect of pressure changes on the sensor, and a pair of the spirals may be mounted oppositely of a thermally conducting disk to minimize temperature differences between the spirals. The mass may be centrally mounted on a disk with the disk peripherally supported, or the mass may be distributed around the disk periphery with the disk centrally supported for isolation from mounting strain.

Abstract: An acoustic sensor, suitable for use as an ultrasonic transducer, microphone or hydrophone, uses an optical lever to amplify the motion of the sensor surface and convert it to an electrical signal suitable for image processing. In the acoustic sensor, a beam of light from a laser is directed at an oblique angle onto a reflective surface coupled to a sensor membrane. The reflected light strikes a position-sensitive light detector (PSD) which generates an electrical signal indicative of the position of the spot of light on the PSD. When an incident acoustic wave strikes the sensor membrane, the small movements of the reflective surface result in large motions of the spot of light on the PSD, thereby amplifying the acoustic signal and converting it into an electrical signal. Also disclosed is a multi-element sensor array suitable for linear array or phased array imaging.