Abstract: The invention relates to a method for optical measuring systems, comprising a sensor element (6) connected to a measuring and control unit (10) via an optical connection (3), and being adapted for providing a signal defining a measurement of a physical parameter (p) influencing the sensor element (6), said method comprising generation of a measuring signal that is brought to come in towards the sensor element (6), and detection of the intensity of the measuring signal (B) in the measuring and control unit (10), after influencing the measuring signal in the sensor element (6).

Abstract: An occupant classification system comprising: a seat upon which an occupant may sit or on which an object may be placed, the seat having one of a seat cushion and a seat back; at least one optical fiber having a measurable optical characteristic, arranged in a specific pattern, the optical characteristics of the fiber changeable when a force is applied to the fiber; and a processor responsive to an output signal from each fiber for generating a control signal determinative of a physical characteristic of an object or occupant on the seat.

Abstract: An optical medium having a cavity that defines a variable gap is provided. The optical medium is used in an optical sensor, laser, and variable frequency resonator, by way of example. The cavity is physically altered in response to changes in a measurable parameter like pressure, temperature, force, flow rate, and material composition. The optical medium is characterized in some embodiments by having a cavity disposed near or within a high Q optical resonator. The optical resonator can be formed by various structures of which Bragg reflector cavities, ring resonators, microdiscs, and microspheres are examples. The optical resonator is preferably coupled to a laser source. The altering of the cavity affects the resonance condition within the optical resonator and thereby the laser signal of the system. If the laser source is a mode locked laser, the repetition rate of the pulse train changes in response to changes in the measurable parameter.

Abstract: A strain sensor comprises an optical waveguide having a plurality of reflecting structure (Bragg grating) along its length. Each structure reflects light at a different characteristic wavelength (&lgr;1 to &lgr;n+1) which changes in dependence on a change of physical length of at least part of the reflecting structure. The reflectivity of reflecting structures which reflect at characteristic wavelengths which are adjacent to each other (&lgr;1 and &lgr;2 or &lgr;n and &lgr;n+1) are configured to be different such that the intensity of light reflected from adjacent structures can be used to discriminate between them.

Abstract: Brillouin scattering spectrum analysis is used to measure strain, displacement, temperature or other physical quantities at any location along an optical fiber attached to a structure. The fiber can be interrogated with different pulse widths for coarse and fine scans. The fiber can also have multiple sensors, either formed in a single fiber or branching off from a backbone fiber, in which case other segments of the fiber can be used for temperature compensation.

Abstract: A touch pad for controlling electronic equipment includes a deformable touch surface and a compressible pad body in contact with the touch surface. The compressible body is formed from a material which scatters or diffuses light within the material. Multiple sources of light or other wave energy are directed into the interior of the substrate to form multiple illuminated cells inside the pad body. Each illuminated cell forms an integrated cavity within the pad body. A detector in communication with the compressible material detects light intensity within the integrated cavity. A processor receives signals from the detector and converts the signals into useable information relating to the position of regions of compression of the pad.

Abstract: A strain sensor has a fiber Bragg grating fastened in a one-quarter circular arc to the strain sensing section of a strain sensor member. One end of the fiber Bragg grating is aligned in the longitudinal direction of the strain sensing section, while the other end is aligned at a right angle to the longitudinal direction. When longitudinal stress is applied, the fiber Bragg grating is elongated at one end and compressed at the other end, creating a high degree of chirp, thereby enabling strain to be measured with high sensitivity. The sensitivity is determined partly by Poisson's ratio, and thus is not limited by geometrical constraints on the strain sensing section.

Abstract: A method and apparatus for monitoring a structure and for locating the position of an event including a light source, a waveguide, and a detector means. The waveguide receives light from the light source so that the light is caused to propagate in counter-propagating optical signals in the waveguide. The waveguide includes the counter-propagating optical signals or some characteristic of the signals modified or effected by an external parameter caused by or indicative of the event to provide modified counter-propagating optical signals. The detector means detects the modified counter-propagating optical signals effected by the parameter and determines the time delay or difference between the modified counter-propagating optical signals in order to determine the location of the event.

Abstract: Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.

Abstract: Fiber optic sensor with transmission/reflection analyzer for detection and localization of a perturbation that generates additional losses in the test fiber.

Abstract: The device serves for changing the length of a running path of an electromagnetic wave. It comprises a wave guide which is wound onto a core. The core is formed in two parts, wherein the distance of the core parts to one another is changeable in order to extend the wave length in a defined manner.

Abstract: In the method and apparatus for providing an optical fiber interconnect, a transmitter transmits an optical signal through an optical fiber. The transmitter does not transmit to a controller, information about the power of the transmitted optical signal near the input end of the fiber. The controller receives an indication of the power of a returned portion of the transmitted optical signal. The controller causes the lowering of the power of the transmitted optical signal to a predetermined level based the received indication.

Abstract: A ribbon-like sensor assembly is described wherein a length of an optical fiber embedded within a similar lengths of a prepreg tow. The fiber is “sandwiched” by two layers of the prepreg tow which are merged to form a single consolidated ribbon. The consolidated ribbon achieving a generally uniform distribution of composite filaments near the embedded fiber such that excess resin does not “pool” around the periphery of the embedded fiber.

Abstract: The present invention relates to a fiber optic rotation sensing device. The sensing device includes a stationary base, a rotatable member, and an optical fiber configured in at least one loop about the rotatable member. The optical fiber is secured to an exterior portion of the rotatable member and to the base. Rotation of the rotatable member causes a distortion of the at least one loop and a change in the intensity of the light passing through the optical fiber. The change in light intensity is measured to provide an indication of the degree of twist of the rotatable member.

Abstract: Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.

Abstract: Sensors and sensing apparatus are described, based on fused tapered fiber optic couplers with the taper waist portion formed into a loop or cleaved to provide a reflecting end. Light is typically input to the taper waist portion along a single input fiber, and bending of the loop or cleaved taper waist portion causes changes in the coupling ratio between the output fibers. The taper waist portion may be formed into a loop with a small bend radius without loss, and sensors embodying the claimed invention are particularly suitable for in-vivo measurement of pressure, the taper waist portions advantageously being arranged in contact with a membrane which deflects according to surrounding pressure. Further embodiments are described which are suitable for measurement of fluid flow velocity and/or acceleration.

Abstract: Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.

Abstract: The invention relates to a frequency-coded fiber laser pressure sensor (1) which is especially suitable for measuring isotropic pressures in oil wells. The sensor principle provided for in the invention is based on the fact that in a fiber laser (2) doped with Er3+ a monomode or bimodal sensor fiber (5, 5a, 5b) is positioned whose pressure-related birefraction results in a frequency shift and beat frequencies between the orthogonal linear polarisation modes x, y or the spatial modes LP01 and LP11straight line. The beat frequencies are easily measured using a frequency counter (19). Temperature-related variations in birefraction are compensated in a differential arrangement of two sensor fiber segments (5a, 5b). Fiber-integrated Bragg gratings (4a, 4b) with low bandwidths (0.2 nm) are especially suitable as laser end reflectors.

Abstract: A differential output optical fiber displacement sensor includes a structure subject to mechanical displacement over a displacement range. A pair of optical fibers is positioned so that the first optical fiber and the second optical fiber bend inversely to each other over at least part of the displacement range when the structure experiences mechanical displacement. The light transmitted through each of the optical fibers is measured, and a differential calculator determines the difference between the two transmitted light signals.

Abstract: Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.

Abstract: A fiber optic acoustic sensor system including an optical conductor having low reflectivity mirrors is provided. Optical sensors are provided by sections of the optical conductor bounded by pairs of the low reflectivity mirrors. Pulses of light are injected into the optical conductor and reflected by the low reflectivity mirrors. The reflected pulses of light are processed using a compensating interferometer to generate interference patterns representative of the environmental conditions acting upon the optical conductor.

Abstract: A detection system for use in detecting the presence of a non-aqueous organic measurand is provided. The system comprises a fiber-optic probe assembly incorporating an optical fiber which is susceptible to micro bending anywhere along its length, and a body of material contained within a rigid containment structure, wherein said body comprises a material selected from the group consisting of a rubber, plastic and semi-crystalline/rubbery polymeric material which is subject to a volumetric change capable of inducing a microbend in said optical fiber in the presence of said non-aqueous organic measurand and wherein the body of material is a substantially continuous coating which has a thickness prior to contact with the non-aqueous measurand of less than 7.

Abstract: Strain sensors, and in particular strain rosettes, are described and claimed, in which the strain sensing elements are fiber Bragg gratings. Strain sensors in accordance with the described invention comprise first and second fiber Bragg gratings, and a length of optical fiber connecting the gratings in series, each grating being substantially straight and the two gratings being non-parallel and having different nominal Bragg wavelengths, the connecting length of optical fiber having a bend, characterised in that a portion of the connecting length is tapered, the tapered portion including an elongate waist portion having a reduced cross sectional area and said bend is formed in the waist portion.

Abstract: A measuring device for providing data corresponding to a geometric configuration in space, in the form of a flexible, compliant, measurement member capable of bending in at least one degree of freedom and extending along a medial axis or plane. The member has spaced flexure sensors distributed at known locations on the member and separated by known sensor spacing intervals to provide flexure signals indicating the local state of flexure present at the locations. The member comprises a multiplicity of formed, i.e. shaped, fibers, these fibers including sensing fibers having sensing portions which provide the flexure sensors, the sensing portions of different fibers being located at differing distances along the member so as to be located at the sensor spacing intervals, the formed fibers being in mutually supporting relationship, as by continuous or repeated contact with each other. Such fibers may constitute most or all of the member.

Abstract: An apparatus for sensing strain applied to a region of a hydrocarbon well comprises an optical fiber in communication with the region. The optical fiber is responsive to strain applied to the region and to a light signal transmitted through it, in order to produce a sensing light signal incorporating scattered light. A characteristic of the scattered light is indicative of the strain being applied to the region.

Abstract: The invention is an integrated optical sensing element for detecting and measuring changes in position or deflection. A deflectable member, such as a microcantilever, is configured to receive a light beam. A waveguide, such as an optical waveguide or an optical fiber, is positioned to redirect light towards the deflectable member. The waveguide can be incorporated into the deflectable member or disposed adjacent to the deflectable member. Means for measuring the extent of position change or deflection of the deflectable member by receiving the light beam from the deflectable member, such as a photodetector or interferometer, receives the reflected light beam from the deflectable member. Changes in the light beam are correlated to the changes in position or deflection of the deflectable member. A plurality of deflectable members can be arranged in a matrix or an array to provide one or two-dimensional imaging or sensing capabilities.

Abstract: A marine seismic fiber optic acoustic sensor system having internal mirrors with a low reflectivity written into the fiber to form a series of continuous, linear sensors incorporated in a single fiber, each sensor bounded by a pair of internal mirrors. A pulsed laser provides optical signals to the fiber at a pulse width less than twice the travel time to assure that there will be no phase or frequency modulation of signals returned from the sensors and reflected optical energy is returned through the same fiber to an optical coupler where it is input to a compensating interferometer to produce interference signals which are then time division multiplexed to produce signals corresponding to acoustic signals received by each mirror bound sensor. Calibration to remove local temperature effects is provided by using a desensitized reference fiber with internal mirrors identical to the sensitized fiber, by a piezoelectric stretcher built into the fiber or any other conventional calibration technique.

Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes an array of sensors that include a plurality of optical fiber coils. The array of sensors senses the fluid flow inside the pipe. At least one optical reflective device is disposed between adjacent optical fiber coils. An isolation pad is disposed between each optical reflective device and the pipe.

Abstract: A method for detecting structural flaws in a structural member that includes plastic composite matrix material involves taking a quantity of matrix material that is substantially free of any non-optic glass fibers, molding the matrix material into a structural loadbearing member having a length and opposite end surfaces, placing a plurality of straight continuous spaced elongated fiber optic strands having the same length as the loadbearing member in the matrix material before molding, loading the structural member to exert stress and strain thereon, exposing one of the ends of the fiber optic strands to a source of light, viewing the opposite ends of the fiber optic strands to determine if light is being emitted therefrom by passing through the fiber optic strands, and making an evaluation of any structural flaws in the member by determining whether light from the light source has been fully transmitted through the fiber optic strands.

Abstract: An apparatus for detecting foreign bodies in fiber material includes at least two light sources. At least one of the light sources has at least three light emitting elements. Each light emitting element radiates a light of different color. An arrangement directs the light emitted by the light sources to the fiber material for illuminating the fiber material, and a sensor detects the illuminating light after illumination of the fiber material for emitting an electric signal upon a sudden color change of the fiber material. An arrangement causes the light sources to alternatingly illuminate the fiber material with different colors, and further, an arrangement selects the color emitted by the light sources as a function of the color of the fiber material.

Abstract: An apparatus and method is described wherein a sensor, such as a mechanical strain sensor, embedded in a fiber core, is “flagged” to identify a preferred orientation of the sensor. The identifying “flag” is a composite material, comprising a plurality of non-woven filaments distributed in a resin matrix, forming a small planar tab. The fiber is first subjected to a stimulus to identify the orientation providing the desired signal response, and then sandwiched between first and second layers of the composite material. The fiber, and therefore, the sensor orientation is thereby captured and fixed in place.

Abstract: A device is provided for measuring a bending load in mechanical constructions, which device enables measurement over a broad range of stresses with high precision and which simultaneously compensates for deviations caused by temperature fluctuations.