Abstract: A method of unobtrusive evaluation of structural material integrity without requiring physical contact for referencing integrity values, comprising: directing an impact source at said structural material; obtaining signal information from the structural material by optical reflectometry; and, processing the signal information to determine physical properties of the structural material.

Abstract: The invention relates to devices and methods for detecting a ligand in a liquid, based on deflection of one or more microscopic cantilevers. Each cantilever has an optical waveguide fixed thereto or integral therewith. Deflection of the cantilever is detected by assessing coupling of light between the optical waveguide on the cantilever and an optical waveguide fixed distally thereto.

Abstract: A micro-tensile testing system providing a stand-alone test platform for testing and reporting physical or engineering properties of test samples of materials having thicknesses of approximately between 0.002 inch and 0.030 inch, including, for example, LiGA engineered materials. The testing system is able to perform a variety of static, dynamic, and cyclic tests. The testing system includes a rigid frame and adjustable gripping supports to minimize measurement errors due to deflection or bending under load; serrated grips for securing the extremely small test sample; high-speed laser scan micrometers for obtaining accurate results; and test software for controlling the testing procedure and reporting results.

Abstract: The present invention provides a method and apparatus mainly for measuring mechanical properties, electrical properties and transducer properties (e.g., electromechanical coupling constant) of piezoelectrics, wherein three measurement specimens of the same material and the same dimension, each having parallel planes, and two insertion plates of the same material and the same dimension, each having known mechanical properties, are stacked alternately, a load is applied to these measurement specimens and insertion plates via the measurement specimens located on both end sides, the displacements in the direction of application of the load are measured before and after application of the load, and an elastic constant of the measurement specimen is determined based on those displacements, and the measurement of the electromechanical coupling constant is applied to the piezoelectrics by using the same apparatus under short-and-open circuit conditions.

Abstract: A system and method relating to the measuring of torque in a rotating shaft is provided. An optical torque sensing system comprises a rotating shaft, wherein a sleeve of photo-elastic material overlays a portion of the shaft. A light emitting component delivers light into the photo-elastic material, wherein the light delivered by the light emitting component is directed through the photo-elastic material along an axis of the rotating shaft. A capturing component captures the light that exits the photo-elastic material. The exiting light comprises fringe pattern data, and a computing system computes torsion strain of the shaft based at least in part on the fringe pattern information.

Abstract: Disclosed herein is an accelerometer and/or displacement device that uses a mass coupled to a rhomboidal flexure to provide compression to an optical sensing element preferably having a fiber Bragg grating (FBG). The transducer includes a precompressed optical sensor disposed along a first axis between sides of the flexure. The top portion of the flexure connects to the mass which intersects the flexure along a second axis perpendicular to the first axis. When the mass experiences a force due to acceleration or displacement, the flexure will expand or contract along the second axis, which respectively compresses or relieves the compression of the FBG in the optical sensing element along the first axis. Perturbing the force presented to the FBG changes its Bragg reflection wavelength, which is interrogated to quantify the dynamic or constant force.

Abstract: A system and method relating to the measuring of torque in a rotating shaft is provided. An optical torque sensing system comprises a rotating shaft, wherein a sleeve of photo-elastic material overlays a portion of the shaft. A light emitting component delivers light into the photo-elastic material, wherein the light delivered by the light emitting component is directed through the photo-elastic material along an axis of the rotating shaft. A capturing component captures the light that exits the photo-elastic material. The exiting light comprises fringe pattern data, and a computing system computes torsion strain of the shaft based at least in part on the fringe pattern information.

Abstract: A method and apparatus for measuring strain on a surface of a substrate utilizes a substrate surface coated with at least one coating layer. The coating layer provides both luminescence and photoelasticity. The coating layer is illuminated with excitation light, wherein longer wavelength light is emitted having a polarization dependent upon stress or strain in the coating. At least one characteristic of the emitted light is measured, and strain (if present) on the substrate is determined from the measured characteristic.

Abstract: A compressed symbology strain gage includes a target in the form of a symbolic strain rosette (“SSR”), the target being associated with a body for which strain is to be measured and being adapted to emit a detectable physical quantity; a sensor compatible with and adapted to pre-process the detectable physical quantity emitted by the target and output data representing the physical quantity adapted to receive signals from the target and provide output signals based thereon; a computer program or programs for analyzing the signals data output by the sensor to define the SSR; and for calculating the strain directly on the body based on the pre-processed and analyzed data. The SSR can be defined either a priori by manufacture or a posteriori by identification.

Abstract: A pressure sensor includes an optical waveguide having an optical fiber with a refractive index n1, located in a fiber guide with a refractive index n3, forming an intermediate region. A medium with a refractive index n2 is located in the intermediate region. The refractive indices correspond to the relation n3>n1>n2. When subjected to a pressure, the fiber guide is pressed against the optical fiber such that the condition for the total reflection required for the normal optical waveguidance in the optical waveguide is no longer fulfilled, and attenuation takes place. The attenuation is evaluated in a corresponding control unit. The pressure sensor is especially provided for an anti-pinch device in the motor vehicle industry.

Abstract: An apparatus and a method for measuring the force (GL) applied by an elastically flexible element (5;71,71?) undergoing a pre-set elastic deformation, more specifically an element that carries a slider (3) and includes a thrust device that applies a force to the flexible element. The thrust device includes, for instance, a pneumatic nozzle (27;57,57?;28) for applying a force (R) to an intermediate portion (4) of the thin plate, at a thrust section (K). A position sensor (30;80) detects the height (z) of the slider—indicative of the deformation of the flexible element. The value (MF) of the moment of the applied torque when the height (ZF) of the slider indicates the pre-set elastic deformation of the flexible element, is utilized for calculating the force to be measured according to the formula GL=MF/L where L is the distance separating the slider from the section of weakness.

Abstract: A single-axial precision measuring apparatus includes a base, a flatbed at the base, a flattening mechanism and a monitor above the flatbed, and a distance measuring mechanism below the flatbed. The characteristics of the invention are that, the flatbed is a transparent plate having a plurality of ventilation openings that are connected with a suction tube of a vacuum suction device; the flattening mechanism is capable of up-and-down displacements, and has multi-sectional halt heights through program controls; and the distance measuring mechanism disposed below the flatbed is capable of transverse movements, and at least has an optical ruler, a laser positioning element and CCD cameras. Wherein, the CCD cameras focus at the measuring points, and transmit images captured to the monitor.

Abstract: The fiber optic pressure sensing system includes a sensor housing formed using MEMS processing. The sensor housing has ribs and grooves in both horizontal and vertical directions relative to the surface to allow the membrane to flex in a consistent manner. The flexing of the membrane allows the pedestal to be repeatedly positioned in response to pressure acting on the extension of the sensor head and membrane.

Abstract: An apparatus for varying the gain of a fiber optic sensor that non-intrusively senses the strain response of a pipe is provided. The apparatus includes a circumferential strain attenuator that has an annular land portion that mechanically couples the attenuator to the pipe. An annular web extends coaxially from the land portion and has a reduced cross sectional area relative to the land, and an annular mandrel portion extends coaxially from the web portion and forms a gap between the pipe and the mandrel. The fiber optic sensor is wound on the circumferential strain attenuator. The web and mandrel cooperate to reduce the strain response of the fiber optic sensor relative to the strain response of the pipe.

Abstract: The invention relates to polymeric/semiconductor thin film strain gauges comprising visible light from spectrometer (10) which is directed onto a thin film passive sensor (12) having a transparent glass substrate (14) and a laminated construction in succession from the substrate (14), of a polyimide layer(18a) a polysiloxane layer (16a) filled with alumina particles, a polyimide layer (18b) and a polysiloxane layer (16b) filled with alumina particles.

Abstract: Improved methods and apparatuses for directly monitoring well casing strain and structural integrity are disclosed that allows for monitoring of potentially damaging strain from any orientation or mode and over long stretches of well casing. In a preferred embodiment, optical fiber sensors are housed within a housing and attached to the exterior surface of the casing. The sensors may be aligned parallel, perpendicular, or at an appropriate angle to the axis of the casing to detect axial, hoop, and shear stresses respectively. The sensors are preferably interferometrically interrogatable and are capable of measuring both static and dynamic strains such as those emitted from microfractures in the well casing.

Abstract: In a fiber-optical strain-gauge of the kind comprising a mechanical construction providing a linear, strain-dependent relative movement of oppositely positioned spaced-apart first and second optical fiber-holding elements in a direction substantially perpendicular to the axial direction of the optical fibers, and in which the varying transmission of light between the two fibers is used as an indication of the strain, the main new feature is that the strain-gauge is manufactured using the following steps: a) prestressing an optical fibre by applying a pulling force, or prestressing the mechanical construction by applying a compressing force; b) fixing said optical fiber to the fiber-holding elements in the mechanical construction; and c) cleaving the optical fiber at the interspace between the fiber-holding elements.

Abstract: The invention relates to various materials and their use in applications which exploit the triboluminescent effect.

Abstract: Improved methods and apparatuses for directly monitoring well casing strain and structural integrity are disclosed that allows for monitoring of potentially damaging strain from any orientation or mode and over long stretches of well casing. In a preferred embodiment, optical fiber sensors are housed within a housing and attached to the exterior surface of the casing. The sensors may be aligned parallel, perpendicular, or at an appropriate angle to the axis of the casing to detect axial, hoop, and shear stresses respectively. The sensors are preferably interferometrically interrogatable and are capable of measuring both static and dynamic strains such as those emitted from microfractures in the well casing.

Abstract: There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout an elastomeric body and activated by deforming the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

Abstract: A method of measuring the adhesive strength of polymer materials that are arranged in a combinatorial library which involves providing a lens array having a plurality of individual lens elements on a surface thereof and a substrate. A pattern of different polymer materials, processing variables or environmental conditions is applied to either the individual lens elements of the lens array or to the substrate. The individual lens elements of the lens array are brought into contact with the substrate and, as the lens array and substrate are separated from one another, changes in contact area of the individual lens elements with the substrate are monitored and used to calculate the adhesive strength of the polymer.

Abstract: Disclosed is an apparatus for measuring a residual stress and a photoelastic effect of an optical fiber, which includes: a light source; a rotary type optical diffuser distanced from the light source in a predetermined distance for suppressing the spatial coherence of a light radiated in the light source; an optical condenser for condensing the radiated light passed through the optical diffuser into a spot where the optical fiber is located; a polarizer for polarizing the light passed through the optical condenser into a 45° linear polarized light from an axis of the optical fiber; a polarization analyzer, installed at 90° angle with respect to the polariscope and attached closely with the optical fiber, to prevent the penetration by the background image of the optical fiber; an optical fiber strain unit including a strain sensor for straining the optical fiber on the polarization analyzer toward a longitudinal direction and measuring the strain on the optical fiber; an object lens for magnifying the

Abstract: The fibre-optical strain gauge comprises a mechanical construction (1) providing a strain-dependent relative movement of oppositely positioned, spaced apart first and second optical fibre ends in a direction substantially perpendicular to the axial direction of the optical fibres (7a, 7b) and uses the varying transmission of light between the two fibres (7a, 7b) as an indication of the strain. The mechanical construction comprises fibre-holding elements (6a, 6b) for securing the two fibres (7a, 7b) to the mechanical construction (1) in an aligned relationship in the unstrained condition.

Abstract: A non-contact method for evaluating stress in a substrate. An impurity is non-uniformly introduced into at least one region of a crystalline substrate. The crystalline substrate is subjected to physical stress. Fluorescence producing energy is directed at the crystalline substrate. A fluorescence produced by the crystalline substrate is measured. The fluorescence is correlated with the stress on the crystalline substrate.

Abstract: A micro-tensile testing system providing a stand-alone test platform for testing and reporting physical or engineering properties of test samples of materials having thicknesses of approximately between 0.002 inch and 0.030 inch, including, for example, LiGA engineered materials. The testing system is able to perform a variety of static, dynamic, and cyclic tests. The testing system includes a rigid frame and adjustable gripping supports to minimize measurement errors due to deflection or bending under load; serrated grips for securing the extremely small test sample; high-speed laser scan micrometers for obtaining accurate results; and test software for controlling the testing procedure and reporting results.

Abstract: The coin-type determining device, for determining the presence or absence of inclined notches formed on the circumferential surface of the coin transferred through a coin transfer path, comprises: a plurality of notch detecting devices provided separately from each other with respect to an axis of the coin; a determining device for determining the presence or absence of inclined notches based on the difference between the notch detection results by the notch detecting devices.

Abstract: A stress of a c-axis-oriented specimen of a tetragonal polycrystal is measured using X-ray diffraction under the assumption of a plane stress state. An X-ray optical system is set in the location of &phgr;=0°, 45° or 90°. An X-ray diffracted at a crystal plane (the direction of the normal thereto is the direction of an angle of &psgr;) with the Miller indices (hkl) is detected. A diffraction angle &thgr; in a strain state is measured in the vicinity of a Bragg's angle &thgr;0 in a non-strain state. Strains &egr; with respect to a plurality of &psgr; are calculated from the difference between the measurement values &thgr; and the Bragg's angle &thgr;0. Specific stress calculation formulae are determined with respect to the tetragonal system having the Laue symmetry 4/mmm. The stress is calculated from the slope of the linear line of plotted measurement results.

Abstract: A fiber grating pressure sensor for use in an industrial process includes an optical sensing element 20,600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20,600 may be used by itself as a sensor or located within a housing 48,60,90,270,300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20,600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.

Abstract: A hydrodynamic bearing includes a fiber optic sensor for measuring static and dynamic bearing forces or loads during operation. The fiber optic sensor is positioned within the bearing through the most direct load path, which is through the pad support for a tilting pad style bearing. In additional to being positioned in the pad support of a tilting pad bearing, the sensor is also placed 1) inside the pad support or on the pad support structure, and 2) oriented perpendicularly with the shaft centerlines. After the sensor location is chosen and the sensor is properly positioned, a calibration procedure is utilized to determine the relationship between the radial load and measured strain for the specific bearing. Once the calibration factor has been determined, the sensor may be utilized in the bearing to measure load during operation.

Abstract: A non-contact method for evaluating stress in a substrate. An impurity is non-uniformly introduced into at least one region of a crystalline substrate. The crystalline substrate is subjected to physical stress. Fluorescence producing energy is directed at the crystalline substrate. A fluorescence produced by the crystalline substrate is measured. The fluorescence is correlated with the stress on the crystalline substrate.

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

Abstract: A fiber optic force sensor for sensing a force exerted upon an optical fiber and comprising a fiber Bragg grating having a Bragg grating (204) formed in a portion of an optical fiber (203), and a plurality of stacked layers (201, 202) into which the fiber Bragg grating is embedded.

Abstract: Methods and systems for evaluating stresses in line features formed on substrates. Stresses may be computed from measured curvature information based on simple analytical functions. The curvature information can be obtained optically by, e.g., a coherent gradient sensing method, to obtain a full-field measurement of an illuminated area.

Abstract: A composite structure contains crystalline and/or polycrystalline triboluminescent elements distributed therein externally and/or internally, totally and/or regionally. The structure is instrumented with at least one optical fiber which is coupled therewith penetratingly and/or superficially/tangentially. Each optical fiber is exteriorly light transparent/translucent along at least a longitudinal portion thereof which is situate in the vicinity of at least one triboluminescent element. Concomitant with the occurrence of damage in and/or on the structure is the occurrence of mechanical action with respect to at least one triboluminescent element, a consequence of which is the occurrence of triboluminescence which, to at least some degree, passes radially into at least one optical fiber so as to reach the optical fiber's transmissive axial core and thereby be transmitted to remotely located photosensitive equipment. The triboluminescent elements can exist wholely and/or partly in various capacities, e.g.

Abstract: A film is placed between contacting surfaces in an assembly. The film has an optical property responsive to pressure. A compressive force is applied to the contacting surfaces to generate an initial pressure pattern. The film is removed from between the contacting surfaces. The optical property is sensed to derive a sensed initial pressure pattern. A stored setting controls the compressive force. The sensed initial pressure pattern is compared to a reference pressure pattern. The stored setting is updated to adjust the compressive force as a function of the comparing.

Abstract: A method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift is disclosed. The present method includes the steps of obtaining mean two peak frequencies in a multi-peak Brillouin spectrum of the dispersion-shifted fiber, determining a temperature change according to the formula of a Brillouin frequency shift of the peak relating to strain and temperature conditions of the fiber, and determining a strain change through the formula. In a 3682-m sensing length of Large-Effective-Area NZ-DS fiber, a temperature resolution of 5° C., a strain resolution of 60 &mgr;&egr; and a spatial resolution of 2 m are achieve simultaneously.

Abstract: The invention describes apparatuses and methods of monitoring fatigue, structural response, and operational limits in structural components. More particularly, the present invention relates to fatigue, response, and operational monitoring systems on steel catenary risers using optical fiber sensors.

Abstract: The fibre-optical strain gauge comprises a mechanical construction (1) providing a strain-dependent relative movement of oppositely positioned, spaced apart first and second optical fibre ends in a direction substantially perpendicular to the axial direction of the optical fibres (7a, 7b) and uses the varying transmission of light between the two fibres (7a, 7b) as an indication of the strain. The mechanical construction comprises fibre-holding elements (6a, 6b) for securing the two fibres (7a, 7b) to the mechanical construction (1) in an aligned relationship in the unstrained condition.

Abstract: A fiber-optic pressure sensor having a pressure measuring head including a housing which accommodates a diaphragm functioning as a pressure transducer and completing a translational movement under applied pressure and including at least one optical waveguide, the face of which is directed to the inside surface of the diaphragm and via which the light emitted by a light source is introduced into the pressure measuring head, the inside diaphragm surface having a pattern of highly reflective areas and areas of low reflectivity.

Abstract: A method and apparatus for evaluation of films, such as low-k thin films with nano-scale pores, are provided. The evaluation may include characterization of the pore structure, the characterization results in determining pore sizes, hence obtaining pore size data. Moreover, the characterization may result in a non-destructive evaluation of mechanical properties, in particular the Young's Modulus, or the effect of interfering physical & chemical factors such as Pore Killers. Further, in line monitoring or studying of pore structure porosity and pore size distribution (PSD) of low-k films and evaluation of the mechanical properties of porous low-k films simultaneously using the same set of experimental data is provided.

Abstract: An apparatus for measuring pressure in a medium includes a laser for emitting linearly polarized light; a polarizing beam splitter that reflects the linearly polarized light from the laser; a first lens that receives and focuses the linearly polarized light from the polarizing beam splitter; an optical fiber having first and second ends, the first end for receiving the linearly polarized light from the first lens, the second end comprising a tip disposed in the medium, the tip receiving reflected light from the medium, the reflected light being transmitted back through the optical fiber and the first lens to the polarizing beam splitter; the polarizing beam splitter transmitting the reflected light that has polarization orthogonal to the linearly polarized light emitted by the laser but not transmitting the reflected light that has polarization substantially parallel to the linearly polarized light emitted by the laser; a second lens for receiving the reflected light that has polarization orthogonal to the li

Abstract: A method of detecting stress and strain using a powder coat finish and photoelastic techniques. A part is provided with a photoelastic layer comprising a non-opaque powder coat finish that becomes optically anisotropic when stressed. Photoelastic techniques are used to detect and measure stress and strain in the part. Fringe patterns appear in the photoelastic layer indicating the locations and magnitudes of the stress and strain when the part is illuminated with polarized light and viewed through a polarizing filter. Stress and strain resulting from applied forces are detected. Structural deformation in parts that have experienced plastic deformation is also detected. Photoelastic techniques using powder coat as a photoelastic technique are less expensive and easier to apply than traditional photoelastic coatings. Applications include testing of prototypes, stress testing, inspection and monitoring of production parts, and anywhere that viewing and measuring of stress and strain are of interest.

Abstract: The present invention provides a simple design for a temperature-insensitive extrinsic polarimetric strain sensor. The sensing element is a thin sheet of photoelastic material that is bonded to the test object. It is illuminated with linearly polarized light with the polarization direction at 45 degrees relative to the strain-induced fast and slow axes in the photoelastic material. The sensor measures the difference between the strains along these two orthogonal directions. The reduced sensitivity of the sensor to temperature results from the fact that the illumination is perpendicular to the surface of the test object. All polarization components that are parallel to the surface will experience identical refractive index changes due to thermal effects. Consequently, a measurement of the difference in strains along two directions in the surface plane is insensitive to temperature.

Abstract: There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout an elastomeric body and activated by deforming the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

Abstract: Disclosed is a fiber optic sensor system for sensing strain of the structure by using a wavelength swept fiber laser as a light source and using a fiber Bragg grating sensor as a fiber optic sensor, comprising: a reference fiber Bragg grating sensor, a fiber Bragg grating sensor array being branched from the reference fiber Bragg grating sensor through a coupler; a strain rate measuring coordinate signal-outputting means adapted to output an optical signal having a certain wavelength, an optical detector being connected to the coupler from which the fiber Bragg grating sensor group and the strain measuring coordinate signal-outputting means are branched for detecting output signals generated from the strain measuring coordinate signal-outputting means.

Abstract: The invention relates to a crack testing system using the dye penetration method or for magnetic crack testing, having an illumination unit, a device for applying testing material and an evaluation station, which has light-emitting diodes (LEDs) as illumination units.

Abstract: A method and system for measuring a strength of a test specimen are provided. The method includes the steps of selecting a tensile load of interest for the test specimen, and bulk heating the test specimen at a localized region such that the test specimen is placed under the tensile load of interest. The method further provides for determining whether the tensile load of interest has caused a failure at the localized region. Bulk heating the test specimen provides a non-destructive evaluation technique that is unachievable through conventional approaches.

Abstract: The object of the invention is a measuring device for measuring small forces and displacements having in a body (1) of the device a detector means comprising a light source (4) and a position-sensitive detector (5), and a sensing means comprising a spring means (2) to be loaded by a force to be measured and a shading means (3) mounted to this spring means (2), which shading means moves under the influence of the force loading the spring means (2) in a light source (4) of the detector means, the beam being directed towards an active surface of the detector (5). It is characterizing for the invention that the detector means and the sensing means are arranged to a common clamp (8) arranged to the body (1) of the device.

Abstract: A strain transducer strand (10) is provided comprising an elongatable central core (12) around which are helically wound one or more plastic tubes (14) each of which contains an optical fibre (16). Each tube (14) is overfilled with the optical fibre (16), such that the fibre (16) is longer than the tube (14). As the transducer strand (10) experiences strain, the core (12), plastic tubes (14), and optical fibres (16) elongate, with the helical winding acting as gearing to produce a reduced elongation in the fibres (16) proportional to the elongation of the transducer strand (10). The degree of elongation may be detected by monitoring the optical properties of light transmitted along the fibres (16). The transducer strand is particulary intended for incorporation into elongate load bearing members, such as ropes.

Abstract: A beltless fiber optic labor contraction sensing device including a fiber optic strain sensor for detecting labor contractions during childbirth. The fiber optic strain sensor includes an optic cable, a light source for transmitting a light beam through the optic cable and a light detector for identifying changes in the optical signal. The fiber optic strain sensor is operable to generate an appropriate response to any changes in the optical signal that are caused by the application of force against the fiber optic cable. An adhesive pad or sensor jacket is provided to secure the fiber optic strain sensor to the mother's abdomen without the use of a belt or strap. The contraction device includes wireless communication for transmitting an output signal to a standard contraction recording device. Further, one or more of the components of the labor contraction sensing device are fabricated so as to be disposable.