Abstract: A method and system for stress engineering of a transparent material can include an imaging system that can visualize a spatial distribution of an internal stress in a transparent material, an actuator system that can induce stress in the transparent material, the actuator system comprising one or more actuator elements, and a feedback system that can communicate with the imaging system and the actuator system, and which can guide an internal stress distribution in the transparent material toward a preferred final state.

Abstract: A flexible conduit for transporting a fluid in a submarine environment, suitable for being inspected by an ultrasonic control method for detecting the presence of water in the annular space.

Abstract: Aspects of the present disclosure generally relate to systems and methods for monitoring the structural health of components. In an aspect is provided a system for monitoring structural health of a component that includes a mechanotropic elastomeric (ME) layer at least partially disposed on a surface of the component, the ME layer having a first portion corresponding to a first end of the component and a second portion corresponding to a second end of the component; a fiber optic light guide coupled to the first end; and a detector coupled to the second end. In another aspect is provided a method that includes pulsing an electromagnetic energy source coupled to a system comprising a ME layer; and detecting a wavelength or wavelength range by a detector, the detected wavelength or wavelength range being responsive to an amount of stimulus and being indicative of a deformation in a component.

Abstract: Apparatus and method of processing a substrate according to a PECVD process is described. Temperature profile of the substrate is adjusted to change deposition rate profile across the substrate. Plasma density profile is adjusted to change deposition rate profile across the substrate. Chamber surfaces exposed to the plasma are heated to improve plasma density uniformity and reduce formation of low quality deposits on chamber surfaces. In situ metrology may be used to monitor progress of a deposition process and trigger control actions involving substrate temperature profile, plasma density profile, pressure, temperature, and flow of reactants.

Abstract: A system for tamper identification. A fastener has a tamper identification surface with a unique grain structure that is altered if the fastener is removed or otherwise exposed to sufficient torque. After a period of time such as e.g., shipment and/or storage of the sealed container, a determination of whether tampering has occurred can be undertaken by examining the grain structure to determine if it has changed since the fastener was used to seal the container or secure the device.

Abstract: A system and method for post-tensioned tendon monitoring includes at least one optical sensor arranged in monitoring proximity to a post-tensioned tendon, a test instrument in communication with the optical sensor, a processor capable of managing operation of the test instrument, a storage device and a display. They further include a database adapted to contain sensor baseline information and sensor measurement data. The test instrument is capable of sending a first wavelength to the optical sensor and receiving a second wavelength from the optical sensor, wherein at least one of the instrument or the processor is configured to analyze the second wavelength and output sensor measurement data for storage in the database. The processor is configured to calculate an amount of tensile loading which exists in the post-tensioned tendon, based on the sensor measurement data and the sensor baseline data, and to provide an output.

Abstract: The invention relates to a flexible pipe system comprising an unbonded flexible pipe having a center axis and a sensor system at least partly integrated in the unbonded flexible pipe. The unbonded flexible pipe has a length and a longitudinal direction along the length and comprises an inner sealing sheath and at least a first sensor containing armoring layer. The first sensor containing armoring layer comprises a plurality of elongated armoring elements arranged around the internal sealing sheath. The sensor system comprises: a plurality of optical fiber sensor units, at least one light pump for the optical fiber sensor units, a data collecting unit, and a computing unit. The optical fiber sensor units are optically connected to the data collecting unit, and the data collecting unit is in data communication with the computing unit. At least one of the elongated armoring elements of the first sensor containing armoring layer is a sensor containing element.

Abstract: A Brillouin analysis sensor system comprising: a Brillouin analysis sensor; a polarization beam splitter/combiner, operably connected to the Brillouin analysis sensor between the sensor and the sensing fiber, for receiving polarized lightwaves from the sensor, combining the lightwaves and launching combined lightwaves waves in the sensing fiber a first direction, and a phase conjugate mirror at a free end of the sensing fiber for receiving combined lightwaves from the polarization beam splitter/combiner, rotating the polarization of the combined lightwaves and launching the rotated combined lightwaves in the sensing fiber in an opposing direction to the first direction.

Abstract: A curvature sensing device 10 comprising, a first fiber Bragg grating (FBG) strain sensor 12, a second FBG strain sensor 14, a flexible piece comprising two end pieces 16, 18 joined by a tubular mid-section 20. The device 10 further comprises 16 contact rollers 22 provided on the internal surfaces of the end pieces 16, 18, which maintain the end pieces 16, 18 tangential to a pipe around which the device 10 is located. The FBG strain sensors 12, 14 are embedded within the mid-section 20 and are arranged in two generally orthogonal planes, so that the curvature is measured in two dimensions. This enables the device 10 to detect both the magnitude and direction of bending/curvature within a pipe. Bending in a pipe is transferred through the end pieces 16, 18 to the mid-section 20. The FBG sensors 12, 14 measure bending of the mid-section 20 from which bending of the pipe can be inferred.

Abstract: A current transformer (5) having a plurality of primary and secondary windings, comprising a top Strain measuring system of wind turbine blades (11) during the performance of static tests that comprises an equipment for measuring the strain at multiple locations in mono-mode optical fibers (5, 7, 9) using Rayleigh scattered light, that includes an OBR interrogator (23), an interface device (25) and an Acquisition System (27), said mono-mode optical fibers (5, 7, 9) being attached to the blade (11) subjected to said tests for obtaining high spatial resolution measurements of the blade strain during said tests. Said optical fibers (5, 7, 9) may be placed whether in a longitudinal direction or in a non-longitudinal direction or in a non-linear shape in given blade sections and may be bonded whether to the outer skin (31) of the blade (11), or into grooves (51, 53) in the outer skin (31) of the blade (11) or embedded between two structural laminates (33, 35) of the blade (11).

Abstract: An optical measurement instrument includes a measurement head and mechanical support elements arranged to support a sample well plate. The measurement head is moved towards the sample well plate and, after the measurement head has touched the sample well plate, the measurement head is moved backwards away from the sample well plate so as to provide a desired distance between the measurement head and the sample well plate. A sensor device is attached to the mechanical support elements and arranged detect a mechanical effect occurring in the mechanical support elements due to force directed by the measurement head to the sample well plate. Hence, the situation in which the measurement head touches the sample well plate can be detected without a need to provide the measurement head with a force sensor. This is advantageous because the measurement head can be a changeable module of the optical measurement instrument.

Abstract: The present invention relates to a portable industrial instrument for performing, in an integrated and two-way manner, an interferometric fringe projection and shearography, on a object to be tested, so that, when the two-way interferometer (1) is associated with the coherent or quasi-coherent projection device (2), the instrument is able to measure the 3D shape of the object by interferometric fringe projection, also known as moiré method, and, when the two-way interferometer (1) is associated with the recording or imaging device (4), the instrument is able to perform shearographic measurements on the object, the direction of the traversing light beam in the interferometer (1) being reversed when shifting from one measurement configuration to the other one.

Abstract: A bridge intelligent cable system with a built-in fiber grating sensor is provided, which is applied in a cable bearing structure such as a cable-stayed bridge, a suspension bridge, and an arch bridge. The system includes an anchor cup, a wire dividing plate, a connecting cylinder, a fiber grating sensor, and a cable body, in which the fiber grating sensor includes a fiber grating strain sensor and a fiber grating temperature sensor, tail fibers of the fiber grating strain sensor and the fiber grating temperature sensor are led out, the packaged fiber grating strain sensor is fixedly connected to an outer-layer steel wire of the connecting cylinder, the packaged fiber grating temperature sensor is suspended on the steel wire of the connecting cylinder, holes are punched in the wire dividing plate, and a preserved steel pipe is buried in advance in the connecting cylinder and the anchor cup.

Abstract: The present invention relates to a kit comprising a supporting device for maintaining a transparent article having a longitudinal axis A, a proximal end and a distal end, said supporting device including a proximal holder including a port intended to receive the proximal end of said article, and a distal holder including a receiving part intended to receive the distal end of said article, said port and said receiving part being aligned on the same longitudinal axis B, said supporting device further comprising compression means for putting said article under longitudinal compression directed towards a center of said article, when said article is mounted on said supporting device with its longitudinal axis A aligned on said longitudinal axis B, and a polarimeter. The invention also pertains to a method for measuring the stress inside an article made of transparent material.

Abstract: A method and a device for dynamic measurement of the radial deformation of a bearing ring (12) of a rolling bearing (10) for a rotating element (16), a glass fiber segment (22) of a fiber optic sensor (24) that is fixed in or to the periphery of the bearing ring, a light signal which has been generated by the light source (30) being injected into the glass fiber segment, and the light signal passing through the glass fiber segment being detected by a detector (34), the longitudinal deformation of the glass fiber segment being determined from the change of at least one parameter of the light signal, when the light signal passes through the glass fiber segment, in order to determine the corresponding radial deformation of the bearing ring.

Abstract: A method and system for simultaneously measuring strain and temperature characteristics of an object involves the attachment to the object of a pair of optical fibers having different refractive indices, the fibers being connected together at least one end thereof, and directing laser light into at least one end of the fibers. The Brillouin frequency of each of the fibers is measure and the strain and temperature characteristics are calculated based on the coefficients of strain and temperature and the measured Brillouin frequencies of the fibers.

Abstract: An ion beam irradiating apparatus has: a beam profile monitor 14 which measures a beam current density distribution in y direction of an ion beam 4 in the vicinity of a target 8; movable shielding plate groups 18a, 18b respectively having plural movable shielding plates 16 which are arranged in the y direction so as to be opposed to each other across an ion beam path on an upstream side of the position of the target, the movable shielding plates being mutually independently movable in x direction; shielding-plate driving devices 22a, 22b which reciprocally drive the movable shielding plates 16 constituting the groups, in the x direction in a mutually independent manner; and a shielding-plate controlling device 24 which, on the basis of measurement information obtained by the monitor 14, controls the shielding-plate driving devices 22a, 22b to relatively increase an amount of blocking the ion beam 4 by the opposed movable shielding plates 16 which correspond to a position where a measured y-direction beam curr

Abstract: Provided are a stress analysis method and stress analysis equipment that enable a detailed stress measurement, by using both a photoelasticity measurement method and a stress measurement (mechanoluminescence measurement) which utilizes a mechanoluminescent substance to measure a stress state of an object. Physical quantities that are measurable include individual principal stress component and a principal stress direction. The photoelasticity measurement method alone cannot measure individual principal stress component values.

Abstract: In a method and system for evaluating sub-critical fatigue crack growth in a semiconductor device, a plurality of energy pulses generated by an energy source are repeatedly impinged onto the semiconductor device for a predefined time interval. The repeated impinging of the plurality of energy pulses induces a mechanical stress within the semiconductor device. The induced mechanical stress, maintained below a threshold and repeated for a predefined number of cycles, causes a formation of a sub-critical fatigue crack within the semiconductor device. A detector detects the presence of the sub-critical fatigue crack leading to a fatigue failure. A rapid determination of a pass or fail status for a fatigue test of the semiconductor device is made by comparing a total number of cycles to fatigue failure to a predefined benchmark.

Abstract: Systems and methods for measuring stress in a specimen are provided. One system includes an optical subsystem configured to measure stress-induced birefringence in patterned structures formed on the specimen. In some embodiments, the optical subsystem may be configured as a spectroscopic ellipsometer, a multi-angle laser ellipsometer, a polarimeter, a polarized reflectometer, or some combination thereof. The system also includes a processor coupled to the optical subsystem. The processor is configured to determine stress in a material of the patterned structures using the stress-induced birefringence measurements. One method includes measuring stress-induced birefringence in patterned structures formed on the specimen using an optical technique. The method also includes determining stress in a material of the patterned structures using the stress-induced birefringence measurements.

Abstract: Photoelastic elements are formed deliberately with stress concentrations so that, when evaluated with a polariscope, more pronounced isochromatic bands or fringes result when loads are applied to these elements or to assemblies of these elements. A kit of photoelastic elements, at least some of which have stress concentrations formed therein, is also disclosed. In addition, a toy for producing color patterns is disclosed.

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: Apparatus and a method for inspecting a topology of a surface (2) of a structural member (1) are provided. The degree to which a known type of stress has been applied to the member may be ascertained using a Moiré grid (8). The method involves providing a range of calibration samples of structurally equivalent members, the samples each having been subject to the known type of stress to a differing respective degree. Measurements taken using the apparatus and method of the invention are then compared with measurements taken from a calibration sample to determine the amount of stress which has been applied.

Abstract: Test apparatus comprising means for holding a sample to be tested, means for altering the strain in the sample, an optical arrangement for monitoring the sample to be tested, and processing means for processing the signals resulting from the monitoring of the sample under test, wherein the environment between the optical arrangement and the sample under test is controlled, and wherein the sample to be tested is located in a position external to the controlled environment.

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 measuring method capable of automatically analyzing quantitatively the inner state of a disk is provided. Linearly polarized light from a light source enters a retarder to produce a desired elliptically polarized state. The elliptically polarized light is then passed through a half-wave plate to rotate the direction of a principal axis of the ellipse. The light is expanded into two dimensions by lens systems and to obtain planar information, and is further transmitted through a disk substrate so that the birefringence of a specimen, which depends on an inner stress state and a polymer orientation state, changes the phase of the light. The light wave with its phase changed is passed through a polarizer arranged perpendicular to the principal axis of the retarder. The CCD detects the light wave as a light intensity.

Abstract: A method for inspecting an aircraft fuselage using an inspection system including a movable detector, wherein the method includes coupling a collision avoidance system to the inspection system detector, monitoring the collision avoidance system during operation of the inspection system, and controlling operation of the inspection system with the collision avoidance system.

Abstract: In a sensor arrangement for sensing temperature and strain, an optical fiber with a Bragg grating therein is arranged on a substrate and embedded in a cover layer. The fiber is initially adhered onto an adhesive carrier, which then positions and applies the fiber onto the substrate. The fiber is point-wise fixed onto the substrate by a binder applied through holes in the adhesive carrier. Next, the carrier is stripped off to leave the fiber on the substrate. A cover layer is applied over the fiber and the substrate. Temperature and strain variations are transmitted from the cover layer into the fiber as non-circularly-symmetrical strains. The strain and temperature can be independently determined using this single sensor, by feeding quasi-depolarized light into the fiber and measuring the overlapping birefringent reflections from the Bragg grating. The full width at half maximum value indicates the temperature, while the Bragg wavelengths indicate the strain and the temperature.

Abstract: A structural specimen coated with or constructed of photoelastic material, when illuminated with circularly polarized light will, when stressed; reflect or transmit elliptically polarized light, the direction of the axes of the ellipse and variation of the elliptically light from illuminating circular light will correspond to and indicate the direction and magnitude of the shear stresses for each illuminated point on the specimen. The principles of this invention allow for several embodiments of stress analyzing apparatus, ranging from those involving multiple rotating optical elements, to those which require no moving parts at all. A simple polariscope may be constructed having two polarizing filters with a single one-quarter waveplate placed between the polarizing filters. Light is projected through the first polarizing filter and the one-quarter waveplate and is reflected from a sub-fringe birefringent coating on a structure under load.

Abstract: A structural specimen coated with or constructed of photoelastic material, when illuminated with circularly polarized light will, when stressed; reflect or transmit elliptically polarized light, the direction of the axes of the ellipse and variation of the elliptically light from illuminating circular light will correspond to and indicate the direction and magnitude of the shear stresses for each illuminated point on the specimen. The principles of this invention allow for several embodiments of stress analyzing apparatus, ranging from those involving multiple rotating optical elements, to those which require no moving parts at all. A simple polariscope may be constructed having two polarizing filters with a single one-quarter waveplate placed between the polarizing filters. Light is projected through the first polarizing filter and the one-quarter waveplate and is reflected from a sub-fringe birefringent coating on a structure under load.

Abstract: A fracture detecting apparatus for identifying fractures in a metallic workpiece includes a fiber optic element securely affixed to the workpiece with a metallic material, such as a metallic solder. Accordingly, a fracture in the portion of the metallic workpiece to which the fiber optic element is attached will damage the fiber optic element. A light source and a detector are connected to the fiber optic element for transmitting light therethrough and receiving the transmitted light, respectively. The detector determines, based upon the reflection or attenuation of the transmitted light, if the fiber optic element has been damaged. Accordingly, a damaged fiber optic element as well as the fracture in the underlying metallic workpiece which caused the damage to the fiber optic element may be detected and repaired prior to causing additional damage to the metallic workpiece.

Abstract: An optical fiber strain sensor is provided which remembers the maximum stn a structure has experienced in a given timeframe. A reflective surface is fixed at one location on the structure, and a multi-mode optical fiber with a flat end is fixed at another location on the structure and is positioned so that its flat end is in contact with the reflective surface. A microbore capillary tube attached to the reflective surface encloses the fiber at its flat end and frictionally retains it in contact with the reflective surface. Increasing strain in the structure pulls the fiber end away from the reflective surface in proportion to the amount of strain; however, when strain is decreasing, the fiber buckles rather than moving closer to the reflective surface. Therefore, the maximum strain is reflected as a maximum distance between the fiber end and the reflective surface.

Abstract: An optical fiber strain sensor is provided which remembers the maximum stn a structure has experienced in a given timeframe. A pair of multi-mode optical fibers with flat ends meet end-to-end within a microbore capillary tube with which the fibers have frictional contact. The fibers are fastened to the structure at two points a known distance apart on either side of the capillary tube. Increasing strain in the structure pulls the fiber ends apart in proportion to the amount of strain; however, when strain is decreasing, the fibers buckle rather than move closer together. Therefore, the maximum strain is reflected as a maximum distance between the fiber ends. When the maximum strain experienced is to be measured, the free end of one fiber is connected to a light source and the free end of the other fiber is connected to a detector.

Abstract: The present invention is a method and an apparatus for the precise quantitative measurement of the magnitude of force exerted at the points of contact on a high density electrical interconnect that quantitatively determines the magnitude of the force. The invention includes the steps of establishing a pressing relationship between a photoelastic material and the high density interconnect, coupling plane-polarized light into the photoelastic material stressed as a result of the pressing relationship with the high density interconnect, coupling of the polarized light being at 45 degrees with the direction of pressing, capturing an image of the fringe pattern of the plane polarized light exiting the stressed photoelastic material, the fringe pattern comprising of fringes wherein the number of fringes varies with the magnitude of the pressing force, and counting the number of fringes produced to determine the magnitude of force exerted on the photoelastic member.

Abstract: A polarization is controlled by introducing a phase difference in an incident light at first, then introducing a phase difference by 45 degrees, and then the polarized light is rotated. The light is passed through an analyzer so arranged that the direction of the transmission axis of the analyzer does not coincide with the principal axes of the means for introducing the phase differences, thereby to convert the polarized condition into a light volume which is used to control the phase differences and the rotation.

Abstract: A system for measuring the angular displacement of a point of interest on a structure, such as aircraft model within a wind tunnel, includes a source of polarized light located at the point of interest. A remote detector arrangement detects the orientation of the plane of the polarized light received from the source and compares this orientation with the initial orientation to determine the amount or rate of angular displacement of the point of interest. The detector arrangement comprises a rotating polarizing filter and a dual filter and light detector unit. The latter unit comprises an inner aligned filter and photodetector assembly which is disposed relative to the periphery of the polarizer so as to receive polarized light passing the polarizing filter and an outer aligned filter and photodetector assembly which recives the polarized light directly, i.e., without passing through the polarizing filter. The purpose of the unit is to compensate for the effects of dust, fog and the like.

Abstract: A structural element is provided with at least one light conduit which is arranged thereon under a selected mechanical initial stress. In this manner, the deformation or breakage can be detected at loads or deformations which are lower than the breaking loads or deformations of the component parts to be monitored.

Abstract: A method and an apparatus for optical strain measurement are disclosed. Prior to the deformation or loading of the object to be tested, the latter is provided with a thin transparent film which adheres well to the object and has a thickness between 3 and 20 .mu.m. After the deformation or during loading, the wavelength-dependent intensity course developed because of the interference of the portion of the beam of light reflected and superimposed at the boundary surfaces of the transparent film is measured and evaluated by a computer.

Abstract: A system for measuring aeroelastic deformation of an aircraft wing in flight or in a wind tunnel utilizing light from a linearly polarized light source (101). The light is transmitted through modulating elements (104, 105) to provide a carrier beam, and a small portion of the beam is reflected through a linear polarizer (107) into a photo-detector (108) for utilization as a reference electrical signal (208). The remainder of the beam is reflected back from a retro-reflector target (700) located on the wing into another photo-detector (114) to provide the target electrical signal (209). The two amplified electrical signals are compared in a phase detector (FIG. 3) for providing an angle measurement output signal E.sub.0.

Abstract: A self-contained, unitary device for collecting and interpreting data reflecting the effect of a force acting on a structure includes a housing adapted to be attached at spaced points to the surface of the structure, an optical sensor within the housing for detecting the relative orientation of spaced surface coordinate vectors of the structure, circuitry within the housing for converting signals from the optical sensor to a form usable by signal-processing electronics also located within the housing. The output of this structural information detector embodies useful information which directly indicates the effect of the force acting on the structure.

Abstract: A deformograph comprises a sensitive element shaped as a tube of an optically sensitive material and fixed in a borehole by cementing the gap between said tube and walls of the borehole. One end of the tube is tapered off and provided with a specular coating, while the other end thereof has a specular coating with transparent sections. There are also provided a polarized light source furnishing a light signal transmitted through the material of the tube, and a sensing unit designed to pick off from the sensitive element a useful light signal indicative of the changing condition of the earth's crust in a given area.

Abstract: In the reflection polariscope using filter with four elements transmitting light of four different wavelengths each polarized in appropriate plane and a photoelastic coating having a built-in dichroic filter an image is recorded. The record is further processed in the Fourier processor using special filters to obtain certain potentials and/or the averaged strains in the photoelastic coating and strains in the coating-prototype interface.

Abstract: There is disclosed a method of analyzing formability, strain level, or a related physical characteristic of a given material for a blank which is formed into a desired shape comprising: providing a blank of said given material; applying a flowable photoelastic coating directly on a selected surface area of the blank which is to be analyzed and allowing the coating to cure; forming the blank into the desired shape, and subjecting the coating to analysis. Also disclosed is a novel calibration technique for quantitatively analyzing strain in the plastic region of the metal.

Abstract: The photoelastic strain gauge coating comprises a sheet of photoelastic material of predetermined shape having a multiplicity of minute discontinuities or sets of discontinuities arranged in a predetermined grid. The predetermined shape and grid, together with boundary devices, provide a standard format to enable use of supporting computer programs. In practicing the method, the coating is bonded to the workpiece surface to be analyzed, and then illuminated by polarized light and photographed. The photograph is then magnified greatly to enable examination seriatim of the patterns at and about each discontinuity or set of discontinuities. The data thus obtained is processed, using the supporting computer programs to obtain a strain field of the portion of the workpiece covered by the coating.

Abstract: The coating comprises a sheet of photoelastic material having a multiplicity of regions, in each of which is a plurality of measuring elements at predetermined angles. Each of the measuring elements has an abutment and a finger in operating contact with each other. There will appear in each finger patterns representative of the strain in the associated portion of the workpiece. These patterns are "read" and the values plugged into formulas to determine the magnitude of the strain in each of the two principal directions, and the angle of the principal directions.

Abstract: This invention relates to a photoelastic load measurement device which measures the load on the cable of the crane by measuring the strain in a particular structural member of the crane and is calibrated to operate an alarm, indicator and/or recorder. A source of polarized light directs a beam of light through a photoelastic plate to an analyzer plate and a photocell. The photoelastic plate is subjected to stress from the structural member which varies with the load on the cable of the crane. The stress in the photoelastic plate subjects the beam of polarized light to temporary double refraction (birefringence), and the intensity of the light received by the photocell through the analyzer plate is dependent upon the degree of retardation of the light in the photoelastic plate. The output signal from the photocell is amplified to operate the alarm, indicator and/or recorder. The device includes apparatus which automatically compensates for changes in ambient temperature and variations in boom angle.