Abstract: By performing optical measurements and evaluating the optical response of an appropriately prepared measurement site, stress-related characteristics, such as intrinsic stress of dielectric layers, may be evaluated due to the dependency of the optical response on stress-induced modifications of the charge carrier mobility of a conductive layer provided below the dielectric layer probed by an optical signal. Consequently, inline measurement results may be obtained in a highly efficient manner, thereby providing the potential for monitoring complex stress engineering strategies during a manufacturing sequence for forming microstructure devices.

Abstract: Disclosed is a method for characterizing a sample having a structure disposed on or within the sample, comprising the steps of applying a first pulse of light to a surface of the sample for creating a propagating strain pulse in the sample, applying a second pulse of light to the surface so that the second pulse of light interacts with the propagating strain pulse in the sample, sensing from a reflection of the second pulse a change in optical response of the sample, and relating a time of occurrence of the change in optical response to at least one dimension of the structure.

Abstract: A new method of photo-reflectance characterization of strain and active dopant in semiconductor structures has been developed for characterization of physical properties of semiconductor structures. The underlying principle of the strain and active dopant characterization technique is to measure photo-reflectance signals occurring nearby to interband transitions in the semiconductor bandstructure and which are highly sensitive to strain and/or active dopant through the effect of the nanometer scale space charge fields induced at the semiconductor surface. To attain this, the present disclosure comprises an intensity modulated pump laser beam and a continuous wave probe laser beam, focused coincident on a semiconductor structure. The pump laser provides approximately 15 mW optical power in the NIR-VIS. The pump light is amplitude modulated by a signal generator operating in the range of 100 kHz-50 MHz.

Abstract: Systems and methods for spectral imaging are disclosed. Such spectral imaging can be used to determine properties of a subject material at different locations upon the surface and/or within the material. For example, strain and/or stress within an imaged area of the material can be determined. A system for spectral imaging can include a light source, a two-dimensional sensor array configured to image light from a two-dimensional area of a subject material, a filter configured to filter light from the subject material before the light is imaged and a processor in communication with the two-dimensional sensor array. The processor can be configured to determine a property of the subject material at a plurality of locations within the two-dimensional area of the subject material. Such spectral imaging systems can facilitate the performance of piezospectroscopic measurements of two-dimensional surfaces in a rapid manner while preserving accuracy.

Abstract: A sensor to detect and map various mechanical stimuli spatially distributed over the area of contact with the surface of the sensor. The sensor is a thin film including a stack of alternating layers of nanoparticles and dielectric materials sandwiched between electrodes. By applying a bias between the electrodes, the applied stimuli to the sensor is converted to light and/or device-current through the stack. The optical signal may be directly focused on a photo detector, such as a digital camera, to image the distribution of the stimuli. The electronic signal in the form of spatial distribution of device-current over the area of contact may be obtained by patterning top and bottom electrodes and analyzed using standard electronics. The sensor has applications in many fields, including medicine, forensics, basic and applied research, and robotics.

Abstract: This invention discloses an optical fiber structured to measure stress. The optical fiber includes a core, substantially surrounding the core is a cladding having a plurality of air holes, substantially surrounding the cladding is a buffer, and substantially surrounding the buffer is a jacket.

Abstract: An object of this invention is to provide stress measurement method that is stress of the measuring object nondestructively in a short period of time.

Abstract: This invention takes advantages of color characteristics of medical devices for the cosmetic and indication purposes. For example, the appearances of the metallic brackets used in orthodontics are improved with colors other than the original metallic color by surface treatment using plasma techniques. For example, orthodontic brackets are made with piezochromic materials. When the archwire's torsion and bending forces are fading due to the movement of the teeth, the color of the pressure sensitive brackets will be changed, and the need of archwire's readjustment to have proper torsion and bending forces is signalized. For example, rehabilitation equipments are made with piezochromic materials. When the pressures exerting on the rehabilitation equipments are different, different colors of the equipments are displayed, and the therapists can then act accordingly.

Abstract: The present invention provides a method and substrate examining device that sequentially and automatically measures at least the thickness and the internal stress of the thin film at a predetermined measurement point on the surface of every manufactured semiconductor substrate to perform quality control on each substrate, and reliably recognizes the cause of defects to improve productivity. The examining device and method accurately analyzes the correlation between film thickness and stress to establish the manufacturing processes necessary for manufacturing a semiconductor substrate of higher performance, and measures the distribution of a physical quantity such as internal stress, index of refraction, and composition of the semiconductor substrate in the film thickness direction, without being influenced by change in ambient environmental temperature thereby further improving examination precision.

Abstract: An optical tactile sensor has a touch pad and a CCD camera for imaging behavior of the touch pad. A CPU processes image information from the CCD camera, extracts information on the size, shape, and center of gravity of a contact region, and extracts information on the size of a fixation region. The CPU obtains a normal force from the size of the contact region, obtains a tangential force from the shape of the contact region and the center of gravity of the contact region, and obtains a friction coefficient from the ratio of the size of the fixation region to the size of the contact region.

Abstract: Disclosed are heat management method, and system, and computer program product that include at least one optical strain gauge that is mounted on a printed board in proximity to an object being monitored for temperature changes. Power for controlling heat to the object is modified in response to changes in the optical reference signal of the gauge, whereby such changes are correlated to the rate of strain change in the object as measured relative to predefined temperature changes of the object being monitored.

Abstract: A color switchable stress/fracture sensor in combination with a structure. The combination apparatus includes a structure requiring stress and/or fracture detection, and at least one elasto-mechanoluminescent material at least partially dispersed in and/or on the structure and/or in a coating on the structure. The combination apparatus further includes at least one fracto-mechanoluminescent material at least partially dispersed in and/or on the structure and/or in a coating on the structure, and at least one fiber optic cable positioned to receive and transmit sufficient light emitted from the elasto-mechanoluminescent material due to stress applied to the elasto-mechanoluminescent material and to receive and transmit sufficient light emitted from the fracto-mechanoluminescent material due to fracture of the fracto-mechanoluminescent material.

Abstract: The present invention provides a method of and a device for measuring the stress in a semiconductor material. An excitation light is irradiated on a semiconductor material formed with a silicon germanium layer and a strained silicon layer in a multilayer structure on a single crystal silicon substrate from the direction of the strained silicon layer.

Abstract: An apparatus for determining physical properties of a mask blank. The apparatus includes, for example, an illumination device for radiating a predetermined light laterally into the mask blank, a detection device opposite the illumination device for detecting the light which has been scattered and/or runs through the mask blank, and an evaluation device for determining predetermined properties of the mask blank from the light which has been scattered and/or has run through the mask blank and has been detected in the detection device. The present invention likewise provides a method for determining physical properties of a mask blank.

Abstract: A passive optical sensor operates independently of light amplitude by using a semiconducting carbon nanotube material. The material has an optical property dependent on wavelength, e.g., wavelength of absorption, ratio of absorptions at two wavelengths, or fluorescence at one wavelength in response to light at another wavelength. The property is changed by compressing the material or exposing the material to a charge. Light is passed through the material so that the change in the property can be detected.

Abstract: A method is described using optical fiber technology to measure the vibration characteristics of long slender structures subjected to dynamic disturbances imposed by water or wind generated loads. The method is based on making bending strain measurements at selected locations along the length of long slender structures such as marine risers or large ropes using fiber optics technology including Optical Time Domain Reflectometry and Bragg diffraction gratings. Engineering interpretation of information obtained from bending strains determines the vibration characteristics including frequency, amplitude, and wave length. Maximum bending strain measurements assess pending structural damage. One application is measurement of vortex induced vibrations (VIV) response of marine risers.

Abstract: The invention comprises systems and methods determining residual stress such as that found in interferometric modulators. In one example, a test unit can be configured to indicate residual stress in a film by interferometrically modulating light indicative of an average residual stress in two orthogonal directions of the substrate. The test unit can include a reflective membrane attached to the substrate where membrane is configured as a parallelogram with at least a portion of each side attached to the substrate, and an interferometric cavity formed between a portion of the membrane and a portion of the substrate, and where the membrane is configured to deform based on the residual stress of in the film and modulate light indicative of the amount of membrane deformation.

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 distribution optical fiber sensor system measures distortion and temperature of a structure with a high spatial resolution. The system has an optical fiber on an object to be measured. A light source emits a first pulse light having a pulse width longer than a transient response of an acoustic phonon and a second pulse light after a time interval during which vibration of the acoustic phonon is maintained thereby supplying the pulse lights to the optical fiber. A detector detects scattering gain spectra of a Brillouin-scattered light created in the optical fiber by the second pulse light at intervals corresponding to twice the time obtained by equally dividing the pulse width of the second pulse light. A controlling/calculating unit calculates distortion and/or temperature based on the scattering gain spectra for sections of the optical fiber corresponding to the scattering gain spectra at the respective time intervals.

Abstract: A micro piezo-optic composite transducer comprises: dielectric material; electrodes situated over opposing surfaces of the dielectric material; an optical fiber embedded in the dielectric material, the optical fiber configured to have a wavelength response as a function of material strain; and piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber.

Abstract: A method is disclosed for calibrating a mathematical model of a component using prototype full-field experimentally collected deformation/strain data. Specifically, the method involves obtaining actual experimental field data using strain sensitive coating material and then mapping said data on a CAD mesh model. The analytical mesh model is then compared to a finite element model that is based on theoretical values referred to as boundary conditions. The finite element model boundary conditions are then calibrated to reflect the values derived from the experimental field measurements. Once calibrated, the model can be used to optimize design of components.

Abstract: This invention relates to a new technique of interrogating fiber grating sensors employed for measuring physical quantities such as temperature and force. The technique involves the edge filtering of transmitted light that occurs when a narrow bandwidth light of suitable wavelength from a laser source is passed through a Long Period Fiber Grating (LPFG). When the characteristics attenuation spectrum of the LPFG is shifting, an energy modulation effect will be achieved when one measures the intensity of the transmitted narrow bandwidth light. The narrow bandwidth strong light is best obtained by the reflection of a broad band light from a fiber Bragg gratings (FBGs).

Abstract: A method for the direct measurement of large strains in ropes in situ using a plastic optical fiber, for example, perfluorocarbon or polymethyl methacrylate and Optical Time-Domain Reflectometer or other light time-of-flight measurement instrumentation. Protective sheaths and guides are incorporated to protect the plastic optical fiber. In one embodiment, a small rope is braided around the plastic optical fiber to impose lateral compressive forces to restrain the plastic optical fiber from slipping and thus experience the same strain as the rope. Methods are described for making reflective interfaces along the length of the plastic optical fiber and to provide the capability to measure strain within discrete segments of the rope. Interpretation of the data allows one to calculate the accumulated strain at any point in time and to determine if the rope has experienced local damage.

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: An extensometer including a base, a tensioned optical fiber, and a Bragg grating. The extensometer relates particularly to monitoring of structures. Part of the optical fiber containing the Bragg grating is arranged in a tube. This part is tensioned between the two ends of the tube. The ends of this part are fixed to the ends of the tube, and the tube is rigidly fixed to a host material.

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 optical fiber sensor system comprising of an optical fiber including plurality of sensitive elements, each sensitive element has characteristic spectral band which in normal undisturbed condition lies in a first wavelength range and, under an influence of some specified condition to be detected, shifts to a second wavelength range; first and second wavelength ranges do not overlap. Means for probing an optical transmission or reflection of the fiber operate within second wavelength range to monitor the changes of the transparency or reflectivity of the fiber caused by the shift of characteristic spectral band into the second wavelength range. The invention provides means for distributed monitoring of equipment or construction structures and detection of specified conditions and can provide alarm signal when the specified conditions become effective.

Abstract: A tape surface strain inspecting apparatus which optically inspects a surface of a tape and surface strain of the tape is characterized by being provided with a light emitting device emitting a light on the surface of the tape and forming a linear image which slants at a predetermined angle for a tape width direction of the tape, an image taking device taking the image formed on the surface of the tape, an image inspecting means investigating an edge linearity of an image taken by said image taking device, and a strain discriminating means discriminating largeness of surface strain of the tape based on an inspection result by the image inspecting means.

Abstract: The present invention is a device to measure wind velocity and/or direction. These measurements may be useful for various outdoor activities including hunting, golfing, sailing, fishing, photography, kite-flying, parachuting, fireworks displays or other activities that are influenced by wind conditions. In broader context, sensitive detection of pressure (force) is important in everything from aeronautics to the design of biological sensors. In general, the majority of existing devices to measure wind depend on wind's interaction with a relatively large mass, thus limiting sensitivity. Although various types of sensors including optical strain gauges with the desired sensitivity exist, they are too large, complex or expensive to be broadly exploited. The present invention provides a relatively simple, inexpensive and sensitive pressure sensor (optical strain gauge) for incorporation in a wind-measuring device.

Abstract: Method and apparatus for providing film stress measurements. The invention provides a method for calculating film stress based on an inverse finite element analysis of a displaced substrate such as a semiconductor wafer. The surface displacement of the substrate is measured, and structural compliance based on an inverse finite element model of the substrate is determined. A stress field is ultimately calculated based on the structural compliance and a stress-load. The stress measurement is output based on values in the stress field. The invention can be implemented in software running on a computer system interfaced to a measurement system such as a stress and flatness gauge.

Abstract: An optical spectrum analyzer (10), receiving a multi-channel optical signal (12). The optical signal (12) is passed through an optical isolator (14) and a fiber coupler (16) to a tunable optical filter. The tunable optical filter comprises one or more fiber Bragg gratings (18) inscribed in a length of optical fiber. The optical fiber is mounted on a means operable to apply a variable strain to the fiber, to they tune the peak wavelength of the Bragg grating (18) over a desired wavelength range, the tunable optical filter thereby reflecting each channel of the input signal (12) in turn. The detector (20) therefore detects a signal only if the input signal (12) contains wavelengths corresponding to the reflection wavelength of a grating (18).

Abstract: A reflected light from a Bragg grating in an electrical transformer or other apparatus at which temperature is to be measured, is positioned by an optocoupler through a second fiber provided with a second Bragg grating whose reflection wavelength is different from that of the first grating. The nonreflected light intensity is measured by a photodetector and is used to signal the temperature measurement.

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

Abstract: A part where a creep void is recognized is observed at an arbitrary magnification by a scanning electron microscope, an optical microscope, and a laser microscope, and the maximum value of creep void crystal grain boundary occupancy is measured in the field of view. The maximum value is applied to a a master curve corrected from the results of a test of simulating an actual machine and a test piece of actual machine size, taking account of internal damage of the machine. Thus the creep lifetime consumption rate of a member is estimated easily with high accuracy.

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: Stress-induced photoelastic birefringence compensates for intrinsic birefringence of cubic crystalline structures in deep ultraviolet (less than 200 nm) microlithographic imaging systems. Both the photoelastic birefringence and the intrinsic birefringence are expressed in a tensor format simplified by the symmetries of cubic crystalline structures. The stress-induced photoelastic birefringence can be sized to individually compensate for intrinsic birefringence exhibited in the same optical elements or preferably to collectively compensate for the cumulative effects of intrinsic birefringence in other optical elements in the lithography system.

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

Abstract: A system for monitoring a fabrication process is provided. The system includes one or more light sources, each light source directing light to one or more gratings on a wafer. Light reflected from the gratings is collected by a measuring system that processes the collected light. The collected light is indicative of distortion due to stress at respective portions of the wafer. The measuring system provides distortion/stress related data to a processor that determines the acceptability of the distortion of the respective portions of the wafer. The collected light may be analyzed by scatterometry systems to produce scatterometry signatures associated with distortion and to produce feed-forward control information that can be employed to control semiconductor fabrication processes.

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 tape surface strain inspecting apparatus which optically inspects a surface of a tape and surface strain of the tape is characterized by being provided with a light emitting device emitting a light on the surface of the tape and forming a linear image which slants at a predetermined angle for a tape width direction of the tape, an image taking device taking the image formed on the surface of the tape, an image inspecting means investigating an edge linearity of an image taken by said image taking device, and a strain discriminating means discriminating largeness of surface strain of the tape based on an inspection result by the image inspecting means.

Abstract: This invention is directed to a method and apparatus for the measurement of web strain in a confined area. The apparatus comprises a fiber optic scope means and a fiber optic tube means operatively connected to the fiber optic scope means. The fiber optic scope means is secured inside the fiber optic tube means. An adjustable stand-off means is placed on the web. In an exemplary embodiment the stand-off means is operatively connected to the fiber optic tube means to provide a fixed but adjustable focal length between an end of the fiber optic scope means and the surface of the web. In an exemplary method, the web surface is marked with a series of reference points. The reference points are visually measured using the fiber optic scope means. After the web undergoes a movement, such as a converting step or fold, the web is again visually examined using the fiber optic scope means. The relative movement of the reference points is visually determined.

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 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: 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: An apparatus and method for measuring residual stress and photoelastic effect of an optical fiber is disclosed.

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: This invention is to provide a method and a system which, by making use of a stress luminescent material, renders it possible to directly observe a stress distribution on the base of a real time without electrical contacts, and to easily measure a stress or a stress distribution and a stress image. Essentially, the invention comprises the steps of adding a stress to a tested body containing a stress luminescent material whose light emission is proportional to the stress, making visually observable a stress distribution over the tested body in accordance with a luminous intensity of the stress luminescent material contained in the tested body, measuring the luminous intensity of the luminescent material of the tested body, comparing the measured value of the luminous intensity with certain correlation data indicating a relationship between the luminous intensity of the stress luminescent material and a stress, thereby obtaining a stress value or a stress distribution over the tested body.

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

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