Abstract: One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

Abstract: A tunable colorimetric sensor/optical filter is based on a lithography-free, asymmetric Fabry-Perot cavity. The sensor has a thin-film structure formed by a lossy, porous nanoplasmonic top film deposited on an actively tunable spacer middle layer, and a reflective base layer (either a metal or semiconductor). The structure is fabricated using wafer-scale PVD processes, and the middle layer responds to the presence of a stimulus in the local environment, by expanding in thickness resulting in a shift in resonance wavelength and thus an obvious change in color of the sensor, which color change is detectable by the naked-eye. Such layered geometries exhibit vibrant, macroscopic structural coloration owing to the broadband optical absorption of the top film, enabling the change in spacer thickness to be transduced visually, circumventing the need for sophisticated optical equipment for signal readout to observe the presence of the environmental stimulus.

Abstract: In various embodiments, a pancake lens block may include (i) a first compound retarder comprising a first plurality of retarders oriented to a plurality of first axes of orientation, respectively, where the first compound retarder is configured to selectively transmit a portion of the emitted light, (ii) a partial reflector that receives the portion of emitted light from the first compound retarder and transmits the portion of the emitted light, (iii) a second compound retarder comprising a second plurality of retarders oriented to a plurality of second axes of orientation that are substantially orthogonal to the respective plurality of first axes of orientation, and (iv) a reflective polarizer configured to reflect the portion of the emitted light selectively transmitted by the second compound retarder back to the second compound retarder.

Abstract: In a measurement requiring a high space resolution using S-BOTDR, a pulse train composed of a plurality of pulses having the interval between the pulses longer than the phonon lifetime is interpulse-code-modulated. A Golay code is used for the interpulse code modulation to eliminate the sidelobes of the correlation in using a technique of correlation. In a technique without using correlation, an Hadamard matrix is used for the interpulse code modulation and the resultant matrix is inverted in the signal processing.

Abstract: An apparatus includes a photoelastic modulator (PEM) optical element including a first driving axis and a second driving axis arranged at a selected angle with respect to each other and perpendicular to an optical axis, wherein the first driving axis and the second driving axis extend respective predetermined non-equal lengths that correspond to respective predetermined non-equal natural first and second PEM frequencies f1 and f2. Methods of manufacture and operation are also disclosed.

Abstract: A glass product stress evaluation system is provided. The glass product stress evaluation system includes a background light source to selectively transmit light of different wavelengths and illuminates a glass product. An imaging device is mounted in proximity to the glass product and develops digitally encoded representations of internal annealing stresses formed within the glass product. The imaging device converts the digitally encoded internal stress representations into digital signals. A plurality of optical devices provides a converging view of the glass product. A plurality of filters is mounted in proximity to the plurality of optical devices and selectively transmits light of different wavelengths to the optical devices, thereby transforming detected imaged stresses in the glass product into visible colors. A processing unit receives the digital images from the imaging device and converts the digital images into visible images. The digital images can be classified into annealing grades.

Abstract: A stress measurement device includes a first obtaining unit obtaining thermal data including information indicating a temperature of a measuring region, a second obtaining unit obtaining data related to stress occurring in one part of the measuring region, and a controller finding stress occurring in the measuring region from the thermal data and the data related to the stress. The controller finds, first waveform data respectively on the one part and a part other than the one part based on a change with time of the thermal data, and second waveform data based on a change with time of the data related to the stress. The controller finds, disturbance data through a deduction of the second waveform data from the first waveform data on the one part, and stress data indicating stress occurring in the part through a deduction the disturbance data from the first waveform data on the part.

Abstract: A measurement method for measuring an effective refractive index difference between two propagation modes of a multimode fiber is provided. The method includes: measuring a first Brillouin frequency shift ?1 by specifying a frequency having a lowest-frequency peak out of peaks in a first frequency spectrum of scattered light in a first propagation mode; measuring a second Brillouin frequency shift ?2 by specifying a frequency having a lowest-frequency peak out of peaks in a second frequency spectrum of scattered light in a second propagation mode; and calculating an effective refractive index difference ?neff in accordance with ?neff=(?1??2)/(2kVL) with use of the first Brillouin frequency shift ?1, the second Brillouin frequency shift ?2, a predetermined wave number k of light in a vacuum, and a predetermined constant VL.

Abstract: The present invention discloses an optical sensor device, comprising: an optical fiber; a transducer; and an intrinsic fiber optic sensor embedded in the optical fiber; wherein the transducer is arranged as to receive an input action and converting such input action into a proportional strain on the intrinsic fiber optic sensor being at least the transducer and the intrinsic fiber optic sensor enclosed by a housing being the housing filled either with a thermally-responsive substance or a pressure-responsive substance being such device characterized in that the substance is a substance whose viscosity is reduced by at least 70% upon the change from ambient conditions to working conditions.

Abstract: A polarizer and fabrication method thereof, a display panel and a display device are provided. The polarizer includes an organic film capable of being aligned during a polarization treatment. The organic film includes at least one first region having a first polarization axis and at least one second region having a second polarization axis. A direction of the first polarization axis is different from a direction of the second polarization axis.

Abstract: A defect inspecting method and apparatus for inspecting a surface state including a defect on a wafer surface, in which a polarization state of a laser beam irradiated onto the wafer surface is connected into a specified polarization state, the converted laser beam having the specified polarization state is inserted onto the wafer surface, and a scattering light occurring from an irradiated region where the laser beam having the specified polarization state is irradiated, is separated into a first scattering light occurring due to a defect on the wafer and a second scattering light occurring due to a surface roughness on the wafer. An optical element for optical path division separates the first and second scattering lights approximately at the same time.

Abstract: A drive device includes a drive member, a light source, a marker, a detector, a signal processor and a strain controller. The drive member includes at least a material which generates a plasmon. The drive member generates strain in response to input energy. The marker is formed on a surface of the drive member. Strain occurs in the marker in accordance with a deformation of the drive member and the marker reflects or transmits light emitted from the light source. The detector detects a light intensity of light reflected from or transmitted through the marker. The signal processor calculates an amount of strain which occurs in the marker based on the light intensity. The strain controller controls an amount of strain of the drive member based on the amount of strain calculated by the signal processor.

Abstract: Method for measuring residual strain in a cured composite part includes taking a first image of at least two spaced apart particles positioned on a side of the cured composite part with the side positioned transverse to a first face side. The cure composite part includes a first ply has fibers and a second ply has fibers wherein the first ply and the second ply are positioned in overlying relationship to one another. At least a portion of the fibers of the first ply are positioned in angular relationship with at least a portion of the fibers of the second ply. The at least two spaced apart particles are associated with the second ply. Further included is a step of removing at least a portion of the first ply and taking a second image of the at least two spaced apart particles.

Abstract: A method for analyzing stress in an object according to spectrum data is provided. The spectrum data is obtained from an interference fringe pattern of the object that results from performing photoelasticity. The method includes: analyzing the spectrum data to obtain three sets of intensity data related respectively to different wavelengths of light used in photoelasticity; calculating wrapped phases according to the three sets of intensity data, respectively; calculating preliminary stress values according to the wrapped phases, respectively; determining a system of stress equations according to a relation among the preliminary stress values; and calculating an estimated stress value using the system of stress equations.

Abstract: Disclosed are a light polarization state detection apparatus, a detection method and a light polarization state modulation method. The light polarization state detection apparatus comprises a lens with a variable birefringence feature as an optical phase modulator, a polarizer as a SOP analyzer, a plurality of common lenses and a CCD as imaging devices, and a data processing and displaying unit. The SOP detection apparatus uses wide special birefringence distribution of birefringence optical elements such as a GRIN lens to obtain the Stokes parameters of light to be measured by CCD single frame imaging, and can rapidly accurately measure the SOP. The SOP detection apparatus is simple in structure, lower in cost without containing any motion parts and electrical modulation devices, and is a fully static full Stokes parameters SOP detection apparatus.

Abstract: A surface-guiding photonic device includes a planar, tempered glass, comprising a bulk layer and a tempered superficial layer contiguous with the bulk layer. The superficial layer is at least partly exposed to air and has an intrinsic gradient refractive index in a direction z perpendicular to a main plane of the glass, whereas the bulk layer has a refractive index that is essentially constant along direction z. The average refractive index of the superficial layer is larger than each of: (i) the average refractive index of the bulk layer; and (ii) the refractive index of air. The glass can include lateral structures, e.g., trenches, extending parallel to the propagation direction y, so as for the device to have a rib waveguide-like configuration. The lateral structures form recesses in the superficial layer, so as to laterally confine radiation propagating in the tempered superficial layer, by total internal reflection.

Abstract: A wavelength locker for use with tunable optical devices may include an etalon, a polarization beam splitter, and a first and second detector. The etalon may be positioned to receive a first beam and may include a first birefringent crystal having a first optical axis and a second birefringent crystal having a second optical axis. The first birefringent crystal may be coupled to the second birefringent crystal such that the first optical axis and the second optical axis are orthogonal to one another.

Abstract: The present disclosure generally relates to techniques for measuring a phase difference between a first set of photons and a second set of photons. The techniques can include directing the first set of photons to a first parametric downconverter, directing the second set of photons to a second parametric downconverter, directing photons output from an exotic photon source to the first downconverter and directing photons output from the first parametric downconverter to a first beam splitter, directing photons output from an exotic photon source to the first beam splitter, directing photons output from the second parametric downconverter to a second beam splitter, directing photons output from the first beam splitter to the second beam splitter, detecting photons output from the second beam splitter, deriving, from the detecting, a phase difference between the first set of photons and the second set of photons, and outputting the phase difference.

Abstract: An optical device, particularly a polarimeter, is provided for analyzing a liquid sample, having: a light-generating system for generating light for the surface irradiation of the sample; a detection system which is set up for the spatially resolved detection of light which originates from the transmission of the light provided for the surface irradiation through the sample; a telecentric optical system with a lens between the sample and the detection system and with an aperture diaphragm in the focal plane of the lens between the lens and the detection system.

Abstract: Disclosed is a lithographic apparatus comprising a member susceptible to deformation and a deformation sensor for measuring a deformation of said member. The deformation sensor comprises a first birefringence sensing element arranged to be subjected to stress in dependency of the deformation of said member and a light system configured to transmit polarized light through the first birefringence sensing element, wherein said polarized light has a first polarization state prior to being transmitted through the first birefringence sensing element. The deformation sensor further comprises a detector for detecting a second polarization state of the polarized light after being transmitted through the first birefringence sensing element and a calculation unit to determine the deformation of said member based on the first and second polarization state.

Abstract: A stress detection device and a detection method for a light-transmissive structure are disclosed. The stress detection device for a light-transmissive structure comprises: a light source, a first polarizer, a light intensity distribution state detection unit and a stress distribution state analysis unit; wherein the light source emits uniform polarized light; during detection, the first polarizer and the light sources are located at opposite sides of the light-transmissive structure, respectively; the light intensity distribution state detection unit is configured to obtain a light intensity distribution state of the polarized light emitted from the first polarizer; the stress distribution state analysis unit is configured to obtain a stress distribution state of the light-transmissive structure according to the light intensity distribution state.

Abstract: A method for the adjustment of an optical measurement system comprises providing an optical measurement system, which comprises, as optical elements, a beam splitter; a first photo sensor, exposed by a first partial beam from the beam splitter; an optical filter; a second photo sensor, arranged downstream of the optical filter, exposed by a second partial beam from the beam splitter. Additionally, the angularity and relative position between multiple optical elements is designed to be adjustable.

Abstract: An accurate measurement method and apparatus using an optical fiber are disclosed. A total change in optical length in an optical core in the optical fiber is determined that reflects an accumulation of all of the changes in optical length for multiple segment lengths of the optical core up to a point on the optical fiber. The total change in optical length in the optical core is provided for calculation of an average strain over a length of the optical core based on the detected total change in optical length.

Abstract: A strain gauge or other device may include a deformable medium and discrete plasmon supporting structures arranged to create one or more plasmon resonances that change with deformation of the medium and provide the device with an optical characteristic that indicates the deformation of the medium.

Abstract: A strain gauge or other device may include a deformable medium and discrete plasmon supporting structures arranged to create one or more plasmon resonances that change with deformation of the medium and provide the device with an optical characteristic that indicates the deformation of the medium.

Abstract: An apparatus for quantifying unknown stress and residual stress of a material to be tested, the material being a birefringent or temporary birefringent material, which includes a light source, a polarizer in front of the light source for converting a light beam from the light source into a beam with linear polarization, a first quarter-wave plate in front of the polarizer for generating circular polarization, a standard material, a second quarter-wave plate, an analyzer, a loading unit, a spectrometer for obtaining transmissivity spectrum of the standard material under the wavelength of the light source and a detecting module connected to the spectrometer to have the transmissivity spectrum of the material to be tested and consequently a stress quantifying formula for the standard material.

Abstract: The present invention provides a distributed optical fiber sensor capable of measuring the strain and temperature of an object to be measured simultaneously and independently with high spatial resolution. A distributed optical fiber sensor FS is a distributed optical fiber sensor which uses an optical fiber 15 as a sensor, and a strain and temperature detector 14 measures a Brillouin frequency shift amount caused by a strain and a temperature generated in the optical fiber 15 by using a Brillouin scattering phenomenon, measures a Rayleigh frequency shift amount caused by the strain and temperature generated in the optical fiber 15 by using a Rayleigh scattering phenomenon, and calculates the strain and temperature generated in the optical fiber 15 from the measured Brillouin frequency shift amount and Rayleigh frequency shift amount.

Abstract: The invention provides a method of obtaining the FBG data in final form (transforming the raw data into frequency and location data) by taking the raw FBG sensor data and dividing the data into a plurality of segments over time. By transforming the raw data into a plurality of smaller segments, processing time is significantly decreased. Also, by defining the segments over time, only one processing step is required. By employing this method, the refresh rate of FBG sensor systems can be improved from about 1 scan per second to over 20 scans per second.

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: Methods and systems for resolving and determining sub-wavelength sized features and stresses by using infrared optical and thermal wavelength probing for holographic or interferometric evaluation and testing for all phases of semiconductor device development and manufacture. Specifically, systems and methods are disclosed for extending the range of optical holographic interferometric inspection for testing and evaluating microelectronic devices and determining the interplay of electromagnetic signals and dynamic stresses to the semiconductor material in which an enhanced imaging method provides continuous and varying magnification of the optical holographic interferometric images over a plurality of interleaved optical pathways of varying optical paths and imaging devices.

Abstract: In accordance with the present invention, a photoelastic layer and a monitoring device with an integrated polarizer for detecting stress and strain is described. Stresses and strains in the photoelastic layer or in the photoelastic monitoring device can be detected using photoelastic methods. The integrated polarizer allows photoelastic inspections to be carried out with non-polarized incident light, thereby reducing inspection costs and time associated with photoelastic analysis. Also in accordance with the present invention, a method is described for photoelastic analysis comprising a photoelastic coating and an integrated polarizer. The integrated polarizer allows for photoelastic analysis using a regular non-polarized light source. Stresses and strains in the photoelastic coating and in the underlying material can be detected easily and quickly.

Abstract: An apparatus for quantifying residual stress of a birefringent material comprises a light source generating light; a vertical polarizer converting a beam of light into a beam with vertical polarization; a standard material being mounted in front of the vertical polarizer; a horizontal polarizer converting a beam of light into a beam with horizontal polarization; an applied force unit applying different forces to the standard material; a spectrometer being mounted in front of the horizontal polarizer and recording intensity of light passing through the horizontal polarizer and transmittance of the standard material and a processing module being connected to the spectrometer, deriving a stress formula from the applied forces and transmittances of the standard material and obtaining a stress distribution of the birefringent material. A method for quantifying residual stress of a birefringent material is also disclosed.

Abstract: An apparatus for quantifying unknown stress and residual stress of a material to be tested, the material being a birefringent or temporary birefringent material, which includes a light source, a polarizer in front of the light source for converting a light beam from the light source into a beam with linear polarization, a first quarter-wave plate in front of the polarizer for generating circular polarization, a standard material, a second quarter-wave plate, an analyzer, a loading unit, a spectrometer for obtaining transmissivity spectrum of the standard material under the wavelength of the light source and a detecting module connected to the spectrometer to have the transmissivity spectrum of the material to be tested and consequently a stress quantifying formula for the standard material.

Abstract: The present invention provides a tool for and method of using an infrared transmission technique to extract the full stress components of the in-plane residual stresses in thin, multi crystalline silicon wafers including in situ measurement of residual stress for large cast wafers. The shear difference method is used to obtain full stress components by integrating the shear stress map from the boundaries. System ambiguity at the boundaries is resolved completely by introducing a new analytical function. A new anisotropic stress optic law is provided, and stress optic coefficients are calibrated for different crystal grain orientations and stress orientations.

Abstract: A apparatus for use in a borehole in an earth formation. The apparatus may include: an electromagnetic source; an anisotropic permittivity material, either natural or manufactured, receiving electromagnetic radiation from the electromagnetic source; and a detector for estimating the electromagnetic radiation transmitted through the anisotropic permittivity material as an indication of a parameter of interest. Also, a method of estimating a parameter of interest using the aforementioned apparatus.

Abstract: The present invention provides a tool for and method of using an infrared transmission technique to extract the full stress components of the in-plane residual stresses in thin, multi crystalline silicon wafers including in situ measurement of residual stress for large cast wafers. The shear difference method is used to obtain full stress components by integrating the shear stress map from the boundaries. System ambiguity at the boundaries is resolved completely by introducing a new analytical function. A new anisotropic stress optic law is provided, and stress optic coefficients are calibrated for different crystal grain orientations and stress orientations.

Abstract: The disclosure is directed to a photoelastic method for measuring the absolute zero crossover temperature Tzc of a sample of materials (transparent glass, glass-ceramic or ceramic) directly, without requiring calibration against a primary technique. The method involves subjecting the sample to a temperature gradient that generates a stress distribution pattern within the sample. When some portion of the sample is at a temperature equal to the Tzc of the material, the pattern adopts an easily identifiable shape whose measurement allows the calculation of Tzc. Silica-titania glass, which has a low thermal expansion, is used as an exemplary material.

Abstract: A correlation image detector is provided that co-registers sonar images by finding peaks in correlation images. To obtain the peaks, the mean of the absolute values of the correlation coefficients in the correlation image is found and the Rayleigh parameter is determined from the mean. Based on the Rayleigh parameter, an appropriate threshold can be determined using a desired probability of false detection. The threshold can be chosen such that the probability of a single false detection over the expected life of the mission for which correlation detection is being performed is extremely low, e.g., one in a million. The peak value in the image is determined and a correlation is considered detected when the peak value is greater than the product of the threshold and the Rayleigh parameter. If a detection occurs, the correlation image detector returns the transformation that co-registers the two images.

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 fibre, for receiving polarized lightwaves from the sensor, combining the lightwaves and launching combined lightwaves waves in the sensing fibre a first direction, and a phase conjugate mirror at a free end of the sensing fibre 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 fibre in an opposing direction to the first direction.

Abstract: The present invention provides a tool for and method of using an infrared transmission technique to extract the full stress components of the in-plane residual stresses in thin, multi crystalline silicon wafers including in situ measurement of residual stress for large cast wafers. The shear difference method is used to obtain full stress components by integrating the shear stress map from the boundaries. System ambiguity at the boundaries is resolved completely by introducing a new analytical function. A new anisotropic stress optic law is provided, and stress optic coefficients are calibrated for different crystal grain orientations and stress orientations.

Abstract: An apparatus for quantifying residual stress of a birefringent material comprises a light source generating light; a vertical polarizer converting a beam of light into a beam with vertical polarization; a standard material being mounted in front of the vertical polarizer; a horizontal polarizer converting a beam of light into a beam with horizontal polarization; an applied force unit applying different forces to the standard material; a spectrometer being mounted in front of the horizontal polarizer and recording intensity of light passing through the horizontal polarizer and transmittance of the standard material and a processing module being connected to the spectrometer, deriving a stress formula from the applied forces and transmittances of the standard material and obtaining a stress distribution of the birefringent material. A method for quantifying residual stress of a birefringent material is also disclosed.

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: An apparatus and method for measurement of the stress in and thickness of the walls of glass containers is disclosed that uses fluorescence to quickly and accurately ascertain both the thickness of the stress layers and the wall thickness in addition to the stress curve in glass containers. The apparatus and method may be used to quickly and accurately measure both the stress in and the thickness of the side walls of glass containers throughout the circumference of the glass containers. The apparatus and method are adapted for large scale glass container manufacturing, and are capable of high speed measurement of the stress in and the thickness of the side walls of glass containers.

Abstract: An apparatus and method for measurement of the stress in and thickness of flat glass or curved glass segments is disclosed that uses fluorescence to quickly and accurately ascertain both the thickness of the stress layers and the wall thickness in addition to the stress curve in flat glass or curved glass segments. The apparatus and method may be used to quickly and accurately measure both the stress in and the thickness of flat glass or curved glass segments at a plurality of various locations therein. The apparatus and method are adapted for large scale flat glass or curved glass segment manufacturing, and are capable of high speed measurement of the stress in and the thickness of the flat glass or curved glass segments.

Abstract: An apparatus and method for measurement of the stress in and thickness of flat glass or curved glass segments is disclosed that uses fluorescence to quickly and accurately ascertain both the thickness of the stress layers and the wall thickness in addition to the stress curve in flat glass or curved glass segments. The apparatus and method may be used to quickly and accurately measure both the stress in and the thickness of flat glass or curved glass segments at a plurality of various locations therein. The apparatus and method are adapted for large scale flat glass or curved glass segment manufacturing, and are capable of high speed measurement of the stress in and the thickness of the flat glass or curved glass segments.

Abstract: The present invention provides a distributed optical fiber sensor capable of measuring the strain and temperature of an object to be measured simultaneously and independently with high spatial resolution. A distributed optical fiber sensor FS is a distributed optical fiber sensor which uses an optical fiber 15 as a sensor, and a strain and temperature detector 14 measures a Brillouin frequency shift amount caused by a strain and a temperature generated in the optical fiber 15 by using a Brillouin scattering phenomenon, measures a Rayleigh frequency shift amount caused by the strain and temperature generated in the optical fiber 15 by using a Rayleigh scattering phenomenon, and calculates the strain and temperature generated in the optical fiber 15 from the measured Brillouin frequency shift amount and Rayleigh frequency shift amount.

Abstract: A compact optical system for a particle analyzer and particle analyzer using same are provided. The optical system for a particle analyzer of the present invention comprises a light source, an irradiation optical system for irradiating particles passing through a flow cell with light from the light source, a photodetector for receiving the scattered light from the particles, a light shielding member for blocking the direct light from the light source from impinging the photodetector, and a detecting lens for directing the scattered light toward the photodetector, wherein the irradiation optical system forms a first focus that focuses the light from the light source on the particle passing through the flow cell, and forms a second focus that focuses the light from the light source at a position between the detecting lens and photodetector, and disposes the light shielding member at the position of the second focus.

Abstract: The present disclosure discloses a method of monitoring a structure by a monitoring system including at least one strain gauge positioned on the structure and a computer processor coupled to the at least one strain gauge. According to at least one embodiment, strain data are acquired using the at least one strain gauge, and it is determined, by the computer processor, whether the structure has undergone plastic deformation according to the strain data. Further, a result is outputted according to the determination of plastic deformation.

Abstract: A physical quantity measuring apparatus utilizing optical frequency domain reflectometry includes a tunable laser; a first polarization maintaining fiber; a polarization maintaining coupler; a second polarization maintaining fiber; a third polarization maintaining fiber; a sensor consists of a fiber Bragg grating formed in a core of the third polarization maintaining fiber; a fourth polarization maintaining fiber; a photodiode detects Bragg reflected light from the sensor and reference light from the referential reflecting end; a controller that detects modulation of an interference intensity between the Bragg reflected light and the reference light; and an incidence part that inputs the measuring light, wherein the incidence part being provided on the first polarization maintaining fiber or on both the second polarization maintaining fiber and the third polarization maintaining fiber.

Abstract: A method includes selecting one of performing ellipsometry or performing optical stress generation and detection. The method also includes, in response to selecting performing ellipsometry, applying at least one first control signal to a controllable retarder that modifies at least polarization of a light beam, and performing ellipsometry using the modified light beam. The method further includes, in response to selecting performing optical stress generation and detection, applying at least one second control signal to the controllable retarder, and performing optical stress generation and detection using the modified light beam. Apparatus and computer readable media are also disclosed.