Abstract: A pressure transducer using as a component for changing shape in response to a change in the pressure being measured a composite elongated body, with specially arranged reinforcing fibers. Such a pressure transducer can use various means for sensing the change in shape of the elongated body, including an optical fiber affixed to the elongated body so as to itself change in length in response to a change in pressure, and having a Bragg grating as part of the optical fiber, with the Bragg grating positioned and arranged so as to convey, in response to an optical signal, information about the change in shape of the elongated body. The elongated body is provided with at least one pair of contra-helically wound reinforcing fibers, which may even be bi-axially braided, and are wound either to amplify the effect of pressure acting on the elongated body or to insulate the elongated body from the effects of pressure and other sources of stress.

Abstract: Tensile testing device, which measures the strain for a tensile testing specimen (24) by means of the relative displacement of the fastening means (2, 14), as a result of that the attachment of the tensile testing specimen (24) is performed in such a manner which is independent of the applied tensile testing force. Furthermore, the device provides a contact-free dimension measurement (26, 27) of the tensile testing specimen (24) simultaneous to the tensile testing procedure. The device enables at the same time a compensation of measured values for machine strain and friction forces, and the pulling speed in the tensile testing procedure is controllable, depending in the appearance of the tensile test curve. Moreover, the maximum tensile stress, various standardised strain measures and the fracture area may be calculated.

Abstract: This invention describes a process for locating the position, orientation d depth of fiber optic sensors embedded in a composite material. The process encompasses the coating of the fiber optic sensor with an X-ray opaque material prior to embedding the sensor in a composite material and then mapping the composite material using radiographic techniques to accurately establish the location, orientation and depth of the sensor. A radiographic film or electronically recorded record of the exact placement of the sensors is prepared that may be referenced during machining operations, correlation of test results and accurate mapping of the structure.

Abstract: A strain isolated optical fibre Bragg grating sensor (1) has an optical fibre (2) provided at or adjacent one end (2a) with the Bragg grating (3). An open mouth cap (4) surrounds the fibre end (2a) and region provided with the Bragg grating (3) at a spacing from the fibre, fibre end and Bragg grating. The cap (4) is sealed to the fibre (2) at the open mouth at a side of the grating (3) remote from the fibre end (2a). The cap (4) is made from a low Young's modulus material and is operable to isolate the grating (3) from strain.

Abstract: A method, technique, and apparatus proof test an optical fiber interconnect by applying an ends off-set stress on the optical fiber until the optical fiber fails or breaks, either immediately (short-term strength), or as a result of the delayed-fracture/"static-fatigue" phenomenon for the given off-set, and, hence, for the given stress (long-term strength), imposed for the measured period of time. If, for instance, the short-term strength is addressed, the off-set is measured at the time of the failure, and the corresponding critical strain of the optical fiber is then predicted. In predicting the critical strain, the method and apparatus iteratively determine the total strain, including non-linear components thereof, for an optical fiber interconnect experiencing the measured ends off-set. The analytical model/method includes the steps of iteratively processing characteristic parameters associated with the optical fiber, and determining the non-linear strain associated with the optical fiber.

Abstract: In a probe disposed at the distal end of a heart catheter for the coagulation of muscle and connective tissues by subjecting them to a high frequency field, a pressure sensor is provided for measuring the axial force effective on the probe tip which pressure sensor inlcudes a plastic body with an axial bore into which a light conductor extends and which has at its end opposite the light conductor a mirror for reflecting light supplied through the light conductor back into the light conductor. The plastic body is resiliently movably supported with respect to the light conductor so that the light reflected by the mirror back into the light conductor depends on the displacement of the probe tip caused by a pressure force applied to the probe tip.

Abstract: A method for measuring strain on a structure having a bore and an untethered fiber-optic strain gauge embedded in the bore, which includes the steps of inserting a coupler portion of a fiber-optic cable into the bore in operative relationship to the fiber-optic strain gauge, and using an optical cavity length measurement device attached to the distal end of the fiber-optic cable to measure the strain on the structure. The coupler portion of the fiber-optic cable is removed from the bore after the strain on the structure has been measured. In an illustrative embodiment, the structure is a fastener, e.g., a rivet, used to join together the aluminum skin and the airframe of an aircraft, the bore being provided coincident with the central, longitudinal axis of the rivet.

Abstract: A reference line mark for an optical extensometer of the invention has a mark main body with a boundary shape, in which a reflectance of light is different from other portions. The boundary shape is arranged such that when the mark main body is integrated in a direction perpendicular to the deformation direction under the condition that the mark is attached to a test piece, results of the integration constitute an isosceles triangle having a base in a deformation direction of the test piece. Thus, data points for obtaining edge portions of the mark can be increased, and error-free approximation can be available. Elongation of the test piece can be measured with high accuracy at high computing speed.

Abstract: A non-destructive measurement method for determining residual stress proximate an intermediate layer in a multilayer thermal barrier coating system by directing a laser beam through an outer ceramic thermal insulating layer with the laser beam illuminating a ceramic-bearing intermediate layer in a manner to cause species present in the intermediate layer to fluoresce, measuring the frequency of the light or photons emitted by the fluroescing species, and comparing the measured frequency shift of the intermediate ceramic layer to the frequency shift determined on like ceramic material under controlled stress states to determine a representation of relative residual stress in the measured coating. The invention can be used to assess integrity or quality control of as-manufactured TBC coatings or to assess remaining coating service life of engine-run TBC coated components during an inspection or repair procedure.

Abstract: This invention concerns a novel optical micromanipulation tool, referred to as the optical stretcher, which may use a tunable laser to trap and deform cells between two counterpropogating beams generated by the laser. It is possible to detect the deformation of cancer cells.

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 weight sensor (10) for sensing a load applied to a vehicle seat (14) includes a light source (16) for providing light and detectors (18, 20, 22, 24) for detecting light received from the light source (16). A member (50, 52, 54, 56) impedes the passage of light between the light source (16) and the detectors (18, 20, 22, 24) in response to the load applied to the seat (14). The light detectors (18, 20, 22, 24) provide a signal to a control device (27) indicative of the amount of light received. In response to the light detector signals, the control device (27) determines a value in accordance with the load applied to the seat (14).

Abstract: It comprises a series of measurement optical fiber (2) segments (2a, 2b, 2c) and a series of stress fiber (3) segments (3a, 3b) extending transversely to a longitudinal direction of the measurement optical fiber segments, the stress fiber segments being disposed in alternation on opposite sides of the measurement optical fiber segments, the fiber segments of at least one series being covered by a protective member (4) enabling the covered fiber segments to move relative to the protective member.

Abstract: The present noninvasive load and pressure sensing system makes use of a transparent pressure vessel that is filled with a compressible fluid, whose refractive index changes as a function of the pressure applied to the compressible fluid to redirect the path of a light beam that is transmitted through the transparent pressure vessel. An incident beam of coherent monochromatic light is applied to a transparent segment of a wall of the transparent pressure vessel, where this incident light beam is refracted by the compressible fluid contained in the transparent pressure vessel. The refracted light beam traverses the transparent pressure vessel and exits the transparent pressure vessel at a point along the opposite wall of the transparent pressure vessel as determined by the refractive index of the compressible fluid, which is determined by the pressure of the compressible fluid.

Abstract: A method for characterizing a sample includes the steps of (a) providing a semiconductor material; (b) applying at least one of an electric field, a pulsed or cw light source, a change in temperature and/or a change in pump pulse intensity to the semiconductor material; (c) absorbing pump light pulses in a portion of the semiconductor material and measuring changes in optical constants as indicated by probe light pulses applied at some time t following the absorption of the pump light pulses; and (e) associating a measured change in the optical constants with at least one of a surface charge, dopant concentration, trap density, or minority carrier lifetime.

Abstract: Described is a procedure for investigating the mechanical-dynamic properties of a work piece, whereby the work piece is subjected to cyclical tensile and/or compression stress in a first direction. A power signal representing the tensile and/or compression stress of a work piece is produced with the use of a power-registering device and produces a length change representing at least one specified section of the work piece my means of a distance-registering device. The power signal and distance signal are fed to an evaluation device, which determines a characteristic value for the mechanical-dynamic properties of the specified section from the power signal and distance signal obtained during one stress cycle.

Abstract: A compound testing machine for testing mechanical properties used for an optical connector does not additionally have each testing machine for each of mechanical properties (such as a tensile force including both a straight pull and a side pull, a flex, a twist and an impact) in testing a mechanical property between optical connectors and other mechanical property between optical fibers of the optical connectors, and includes only one testing machine for simultaneously testing various mechanical properties in order to enhance a test machine's efficiency.

Abstract: Methods and apparatus for evaluating internal film stress on a sample at high lateral resolutions are provided. The sample comprises at least one material and has a planar or smooth surface. To determine internal stress, a calibration curve correlating a set of first ellipsometric parameter amplitudes to a set of first stress values is generated. One first stress value is correlated to one first ellipsometric amplitude. Then, the sample for which stress is to be determined is rotated as a function of sample rotation angle a and is measured for a set of second ellipsometric parameter at a selected area of the sample to determine a second ellipsometric amplitude. The internal stress at the selected area of the sample is then determined from the calibration curve by using the second ellipsometric amplitude as an index to determine a corresponding stress value from the calibration curve.

Abstract: Apparatus for the measurement of out of plane displacements of a panel of material under test comprises; a laser (2) capable of focusing a laser spot (8) onto the surface of the panel (6) of material; a line generating lens (12) for converting the image of the projected laser spot (8) into a focused line (22); and, a photo diode (16) responsive to illumination by laser light and so orientated and disposed in relation to the generated laser line (22) that the out of plane distortions of the panel (16) and resulting movement of the spot (8 to 8') produce a corresponding translation of the generated line (18) across the face of the photo diode (16) and the photo diode (16) produces a recordable output proportional to the out of plane deflection of the panel (6).

Abstract: The present invention features an apparatus for detecting a shoulder load between two components in a drill string, comprising a pin connection, a box connection and a washer for sensing tensioning strain force therebetween. The pin connection has coupling means, and the box connection has corresponding coupling means for coupling to the pin connection to form a drill string. The washer is arranged between the pin connection and the box connection. The washer has embedded fiber optic Bragg Grating sensors that respond to a compressive strain shoulder load force when the pin connection is coupled to the box connection, and further responds to a light signal, for providing a compressive strain shoulder load force light signal containing information about a sensed compressive strain shoulder load force between the pin connection and the box connection in the drill string.

Abstract: An apparatus for measuring the reliability of a swage mount interconnecting components of a workpiece using a computer-controlled apparatus. The apparatus includes a mechanism that connects the components by a swaging process under precisely controlled conditions and a mechanism to subsequently cause the swaged connection to fail under controlled conditions. A computer-controlled power twist mechanism applies known, controlled torques to the swaged test components. A laser beam detection system is used to monitor any displacement of the test components as the torque is applied.

Abstract: The present invention features an apparatus that provides an indication of tensioning strain when it is tensioned with respect to a workpiece, comprising either a bolt, stud or fastener together with an embedded fiber optic Bragg Grating sensor. For example, the bolt has a head at one end, threads at the other end and a central bore with a bore wall drilled into at least one end thereof. The bolt responds to a tensioning force applied on the head of the bolt, for providing a tensioning strain force applied inwardly on the wall of the central bore. The fiber optic Bragg Grating sensor is arranged inside the central bore of the bolt and bonded, for example by epoxy, to the central bore wall. The fiber optic Bragg Grating sensor responds to the tensioning strain force, and further responds to a light signal, for providing a fiber optic Bragg Grating sensor light signal containing information about a sensed tensioning strain force on the bolt when the threads are tensioned to the workpiece.

Abstract: An improved method for measuring residual stress in a material comprising the steps of applying a spot of temperature indicating coating to the surface to be studied, establishing a speckle pattern surrounds the spot of coating with a first laser then heating the spot of coating with a far infrared laser until the surface plastically deforms. Comparing the speckle patterns before and after deformation by subtracting one pattern from the other will produce a fringe pattern that serves as a visual and quantitative indication of the degree to which the plasticized surface responded to the stress during heating and enables calculation of the stress.

Abstract: A strain gauge includes an image sensing device having a lens, a magnification lens optically coupled to the lens, a positioning mechanism connected to the image sensing device, an image capture device for receiving an image from the image sensing device, and a processor for mathematically analyzing the image received from the image capture device and to calculate strain.

Abstract: A first aspect of the invention relates to an epoxy resin coating used in reflection photoelasticity, which is "black" in the infra-red part of the spectrum; another aspect to the use of an epoxy resin as a coating on at least one surface of a body to be subjected to cyclic loading and examined by thermoelasticity, and another aspect to a method of making thermoelastic measurements of a body when subjected to cyclic loading and hence measurements of stresses or strains, comprising, as an initial step, coating the surface(s) of the body to be measured with an epoxy resin whereby the surface(s) so coated represents a black body.

Abstract: A measurement device and method for measuring tension in an optical fiber or wire. The measurement device includes a device for producing a vibration surge in the optical fiber or wire which vibrates at a certain, pre-selected frequency and advances as a linearly polarized wave. An optical location-sensitive detector measures the advancing speed (v) of the wave. An illuminator device illuminates the optical fiber or wire so that a shadow or an image of the vibrating fiber or wire is cast onto the indictor whereby the tension (T) of the optical fiber or wire is calculated from the equation T=v.sup.2 .multidot.M, when M is the fiber mass per unit of length of the optical fiber or wire. The indicator device measures the time at which a departing wave surge passes by the indicator and the time at which an arriving wave surge reflected from a subsequent coating vat, or other wave reflector, passes by the indicator.

Abstract: The disclosed method determines at least a first measurement parameter of an object by locating the object in a measurement interaction volume having a light absorbing background and passing through that volume a measurement light beam which has at least two spectrally different wavelengths of light. The measurement light is interacted with the object to product measurement outgoing light which is light reflected from the object while in the measurement reaction volume. That outgoing light is filtered into at least two spectrally different outgoing light portions which are detected and generated therefrom are signals which are a function of the at least a first measurement parameter which is then determined from those signals.

Abstract: New types of fiberoptic microbend sensors are in the form of flexible tapes wherein single or multiple layers of mechanically tough flexible tapes form two outside surfaces of the sensors including between them one or more continuous elongated optical fibers, a variety of monofilaments, wires, threads, meshes, ribbons and or like elements to act as deformers to the optical fiber and sufficient adhesive material to form a permanent flexible tape structure. Additional layers of film, optical fibers, and/or deformer elements may be included to augment or modify the intensity of light that issues from the output end of the optical fibers when they are illuminated at their input end while the surface films of the sensor are subjected to pressure, such as when the sensors are used to weight or detect passage of automobiles. Detection or measuring systems and methods using the flexible sensor tapes are disclosed.

Abstract: Strain in concrete is sensed by a helical optical fiber embedded in the concrete and connected at one end to an external light source, and at the other end to a light detector, providing a signal output to an information processor, which provides a display of the strain in the concrete.

Abstract: A fixture for testing the resiliency of vehicle bulb-type weatherstripping before and after the weatherstripping has been heat treated includes a base and a holder movably positioned on the base for holding the weatherstripping. A ram is movably disposed on the base opposite the holder for motion between a compressed position, wherein the ram abuts the weatherstripping to compress the weatherstripping, and a release position, wherein the ram is distanced from the weatherstripping. A laser device is positioned for directing laser light onto the weatherstripping as it recovers from a compressed configuration to a relaxed configuration. As the weatherstripping recovers, the laser light is reflected off of the weatherstripping, detected, and a detection voltage is correlated to a distanced moved by the weatherstripping as a function of time. Thereby, a measure of the resiliency and recoverability of the weatherstripping is provided.

Abstract: A method and optical system is disclosed for measuring an amount of stress in a film layer disposed over a substrate. The method includes steps of: (A) applying a sequence of optical pump pulses to the film layer, individual ones of said optical pump pulses inducing a propagating strain pulse in the film layer, and for each of the optical pump pulses, applying at least one optical probe pulse, the optical probe pulses being applied with different time delays after the application of the corresponding optical probe pulses; (B) detecting variations in an intensity of a reflection of portions of the optical probe pulses, the variations being due at least in part to the propagation of the strain pulse in the film layer; (C) determining, from the detected intensity variations, a sound velocity in the film layer; and (D) calculating, using the determined sound velocity, the amount of stress in the film layer.

Abstract: A technique for determining properties such as Young's modulus, coefficient of thermal expansion, and residual stress of individual layers within a multi-layered sample is presented. The technique involves preparation of a series of samples, each including one additional layer relative to the preceding sample. By comparison of each sample to a preceding sample, properties of the topmost layer can be determined, and residual stress at any depth in each sample, resulting from deposition of the top layer, can be determined.

Abstract: The present invention relates to a method of testing and/or monitoring structural adhesively bonded joints by the introduction of transducers into the stress or strain field effected by the movement of said adhesively bonded joints under load, such that the load transfer characteristics between the bonded materials and the adhesive can be recorded thus allowing the quantification of the integrity of the adhesive bond lines in such joints. The method assesses the integrity of the bond by comparing the difference in maximum and minimum ratios and curve perameters relating to stress and strain with those of the "at assembly" values.

Abstract: The objective of the present invention is to offer an optical fiber strain-measuring apparatus, which allows the measurement of the strain at an arbitrary position within an optical fiber. An optical frequency conversion section 3 shifts, in a step-wise manner for prescribed frequencies, the frequencies of a continuous light emitted from a light source 1. A sound-light switch 4 coverts into pulses the continuous light forwarded from the optical frequency conversion section 3. When those light pulses are entered into a test optical fiber, back-scattered light is generated. An optical directional coupler 11 branches and forwards to an optical ring circuit and to an optical directional coupler 13 the back-scattered light. A photo-electric converter 14 receives employing heterodyne detection and converts into electric signals the synthesized light signals of the back-scattered light forwarded from the optical directional coupler 11 and the continuous light forwarded from the optical directional coupler 2.

Abstract: A system (50) for determining strain includes: a stimulating light source (54, 56); a device (64) for placing stress on an object (58); a number of local strain gauges (66) attached to the object (58); and an image capturing device (62, 64). A controller (52) is coupled to the stimulating light source (54, 56) and has a signal that turns on the stimulating light source (54, 56). The controller (52) receives a strain signal from each of the local strain gauges (66) located on the object (58). The controller (66) has an image signal that determines when the image capturing device (62, 64) captures an image.

Abstract: The present invention is disclosed comprising a light source, photo detector and a lens system as its main parts. The effect of light intensity on changing current through the photo detector due to the linear or angular displacement of the detector with respect to the light source is the focusing point of this idea. The basic unit of this invention consists of a light source and a detector aiming at each other with a set of lens in between and all are pre-assembled on a film of polymer. The assembly then can be glued on the surface of any test specimen to measure any possible strain. As an alternative, two heads of fiber optic cables can be preassembled on the mounting polymer pointing toward each other. In this method, optical fibers are used to carry the light and the light source and detectors can be isolated from any ambient electro magnetic noise and away from the testing equipment. Lenses are utilized to either converge or to columnate the light rays.

Abstract: Position of a diffusely scattering surface is detected by interfering backscattered light from respective input beams which illuminate a common spot. Through polarization of the input beams and appropriate filtering, backscattered light is isolated from specularly reflected light and interfered to form a fringe pattern on a detector. The position sensor has particular applicability as a push pin sensor in a hard disk servo system.

Abstract: A method or an apparatus for enlarging the range of measurement of speckle measuring systems for elongation measurement on a sample in a testing machine employs a speckle sensor, the sample in the testing machine being loaded in a loading device and the speckle sensor being moved jointly therewith on loading of said sample.

Abstract: A rolling weight deflectometer for monitoring deflection of pavement under load. The deflectometer incorporates an alignment laser beam emitter that measures vertical displacement of each of a plurality of distance sensors mounted on a horizontal sensor bearer member that bends or vibrates as it is transported over a pavement for deflection measurement. The measured vertical displacements, due to member bending, allow the deflectometer to compensate for errors introduced by member bending and thereby provide a more accurate measurement of pavement deflection.

Abstract: A measurement optical fiber is placed into contact with a geological structure, and a reference optical fiber of about the same length is not contacted to the geological structure. An input beam of light is transmitted down the lengths of the measurement and reference optical fibers, and the interference fringes formed between the reflected beams in the two optical fibers are counted to determine the geological displacement, and thence the geologic strain, experienced by the measurement optical fiber. Preferably, multiple pairs of the measurement and reference optical fibers are used, the optical fibers of the various pairs being of different lengths. The difference in displacement measured by any two pairs is a measure of the geological strain in the region between the ends of the two pairs. The multiple pairs are conveniently provided in two optical fiber cables, a measurement cable which contacts the geological structure and a reference cable which extends parallel and adjacent to the measurement cable.

Abstract: A computer system (1) has a data base (DB1) of analytical procedures (AP) for analysing a material sample (30) using radiation such as X-ray radiation. The computer system requests a user to input to the system (1) information for identifying at least one desired parameter (P.sub.d) of the material sample (30). The computer system (1) uses this information to identify the possible analytical procedures for determining that desired parameter. An analytical procedure or procedures selected by the user and/or computer system is then simulated by the computer system to produce a first simulation (I.sub.1) of radiation leaving the sample. The selected analytical procedure is simulated again after the computer system has varied the influence of the desired parameter (P.sub.d) to produce a second simulation (I.sub.2). The computer system then compares the first and second simulations (I.sub.1 and I.sub.

Abstract: A method for measuring torsional stress and axial stress of a rotating workpiece includes the step of arranging at a surface of the workpiece at least two reflector pairs such that connecting lines between reflectors of each reflector pair are slanted relative to one another. The workpiece is rotated about an axis of rotation. A coherent laser light is impinged onto the at least two reflector pairs to produce reflected and interfering light beam pairs for each one of the reflector pairs. The phase difference between the light beams of each light beam pair is determined and the torsional stress and axial stress are calculated from the phase difference.

Abstract: A stress detection apparatus is provided. A piece of semiconductor grade, ngle crystal silicon mounted on the material is illuminated by an infrared source with radiation having a wavelength in the range of 800-1100 nanometers. An infrared detector monitors the photoelastic effects of illuminating the single crystal silicon with the radiation.

Abstract: An opto-mechanical torque sensing device suitable for use with rotary machinery integrates a photoelastic polymer detector, a light source, a photoelastic image sensor and an artificial intelligence neural network and algorithm. The photoelastic polymer is formed into a hollow cylinder and bonded to metal collars located at each end of the cylinder. The collars serve to readily place the cylinder detector over a machine shaft and affix it to the shaft using a keyway, setscrew, or spring pin. Alternatively, split collars and a split sleeve can also be used to clamp the detector to the shaft. In the presence of polarized light, the photoelastic polymer detector generates an optical fringe pattern that varies as a function of torque applied to the shaft or other machine part on which the detector is mounted. The artificial intelligence neural network learns the mapping relationship between the observed optical fringe pattern and the applied torque using a training procedure.

Abstract: A dynamic and thermal mechanical analyzer incorporating a slide driven vertically in an air bearing guidance system with a large displacement capacity, very low friction and low mass. The position of the slide is measured by digitizing and interpolating two quadrature output signals generated by an optical encoder with very high spatial resolution and a long stroke. A force is applied to the slide using a linear permanent magnet motor with high force, high force linearity and low sensitivity to temperature variations. Position signals derived from the digitized and interpolated quadrature output signals are analyzed as a function of the applied force to calculate viscoelastic properties of a sample of material.

Abstract: A birefringent bias is provided to an optical sensor by the addition of one or more single birefringent elements where the total birefringence-length product remains within the accepted tolerances of current devices. The bias provided by two or more elements is such that where each element has a birefringence, a dB/dT and a coefficient of thermal expansion term, the elements are arranged in tandem so that the combined birefringence terms equal the required birefringence bias and the dB/dT and coefficient of thermal expansion terms effectively cancel.

Abstract: A piece of single crystal silicon is embedded in a material such that the licon is flush with the surface thereof. The silicon is illuminated with infrared radiation having a wavelength in the range of 800-1100 nanometers. Isochromatic fringe patterns projected from the silicon are monitored as a direct indication of the amount of stress experienced at the surface.

Abstract: A sensor configuration increases the usefulness of Fiber Optic Displacement Sensors by mounting them on an elastomer substrate. The sensor configuration can also be used for most other sensors. The elastomer substrate is used to pre-mount the sensors, making field installation easier, increasing the range of the sensors, allowing strain sensors to measure compression and elongation, and providing a mechanism whereby the sensors can be protected from failure due to excess strain. The sensing range of the sensor is increased by employing an elastomer substrate to which only a portion provides mounting for the fiber, thereby significantly enhancing the dynamic range of the sensor.

Abstract: This invention comprises an improved rotational displacement apparatus for measuring accurately the twist induced in an extension-twist coupled specimen in response to application of an axial load. The apparatus has an internal cylinder within which a piston rides. A piston rod extends from the piston through a pair of radial ball bearings in the base of the cylinder block to a free end outside the cylinder block. The piston is sized to be slightly smaller in diameter than the cylinder to provide a small space between the piston and the cylinder walls. Means for supplying compressed air to the region of the cylinder below the piston and means for venting air from the region of the cylinder above the piston are provided. An optical encoder is coupled to measure rotational motion of the piston within the cylinder.

Abstract: An assembly which allows use of Fiber Optic Displacement Sensors in a high-temperature environment. The package described is protected against harsh environments. Provisions are taken to allow averaging strains over distances of at least 1/2 to 4 feet, and to allow installation in cramped spaces. A rod is attached to an underlying surface at one point and guided to move in a selected direction of measurement. The distance between a selected movable location on the rod and a point fixed on the surface, is measured using a bent optical fiber having light loss characteristics dependent on that distance. The fiber is gold coated and the holders, guides and other hardware are enclosed in heat shielding trays in which a plurality of sensors are positioned at selected locations along a steam pipe, boiler, vessel or other surface.