Abstract: Local birefringence is determined from a scatter signature of a birefringent waveguide. Four copies of a Rayleigh scatter time delay domain signature of the fiber are collected from two orthogonal polarization received states and from two orthogonal polarization launched states to form a Jones transfer matrix. Obtaining the Jones transfer matrix for the waveguide eliminates the need to align the instrument polarization launch state to the birefringence axes. Birefringence is determined from an autocorrelation of a polarization state averaged function calculated from the transfer matrix terms. Alternatively, the transfer matrix is rotated until fast and slow eigenvectors are separated, fast and slow amplitude functions are generated, and a cross-correlation is performed on the fast and slow amplitude functions in order to determine the birefringence.

Abstract: Biological specimen recovery materials include cellulose acetate nanofibers that are capable of dissolution upon contact with a liquid comprising a dissolution effective amount (e.g., between about 1 to about 10M) guanidinium isothiocyanate (GITC). Kits containing the materials (e.g., in the form of a swab, filtration media or surface wipe) and a dissolution liquid containing the dissolution effective amount of guanidinium isothiocyanate (GITC) are also provided.

Abstract: One example coherent optical time domain reflectometer device includes a coherent light source that produces coherent probe light pulses at an optical wavelength; an optical coupling unit coupled to f a fiber link under test to direct the coherent probe light pulses into the fiber link and to receive reflected probe light pulses from the fiber link; an optical detection unit to receive the reflected probe light pulses and structured to include an optical interferometer to process the reflected probe light pulses along two different optical paths to generate different optical output signals from the reflected probe light pulses along different optical paths, and optical detectors to receive the optical output signals from the optical interferometer; and a device controller coupled to the optical detection unit to extract information on spatial distribution of acoustic—or vibration—or strain-dependent characteristics as a function of distance along the fiber link under test.

Abstract: An inspection apparatus detects one or more characteristics of a material sample and includes a transmitter to transmit an initial signal to the material sample, and a receiver to receive a detected signal from the material sample associated with the initial signal. The detected signal has at least a first harmonic signal component and a second harmonic signal component. Data processing circuitry determines a resonant frequency of the first harmonic signal component and an amplitude of the first harmonic signal component at the resonant frequency, and filters the detected signal using a first filter signal having a frequency corresponding to the first harmonic signal component and a second filter signal having a frequency corresponding to the second harmonic signal component. A frequency analysis is performed in the frequency domain on the filtered first and second signals to determine corresponding first and second amplitudes. The first and second amplitudes may be compensated for nonlinearity.

Abstract: A system for performing distributed measurements of in-situ stress includes an expandable element with at least one fiber optic sensor. The expandable element can be positioned at various depths in a hole in a substrate. A pressurizing device expands (and contracts) the expandable element when the expandable element is inserted in the hole in the substrate to exert pressure on the hole wall. A pressure sensor provides a sensor output indicative of a pressure applied to the hole wall by the expandable element. The fiber optic sensor and an optical interrogator measure strain along a length of the sensor in a continuous, high spatial resolution manner Based on the measured strain and pressure sensor output, the system determines various properties of the substrate such as, minimum principal stress, maximum principal stress, and/or principal stress direction associated with one or more fractures in the substrate, as well as substrate modulus.

Abstract: The present disclosure relates to optical switching devices and switch modules that are designed for long-term security monitoring of high-value infrastructure access entry points. Embodiments in accordance with the present disclosure include optical switches based on fiber-Bragg gratings whose operating wavelengths are based on the presence or absence of magnetic coupling between an embedded permanent magnet and an external element. By monitoring the spectral position of the operating wavelengths and/or the magnitude of a light signal at the operating wavelengths, the state of the magnetic coupling can be determined and used as an indicator of whether the security switch has been actuated.

Abstract: A high-speed interrogation system is provided for interferometric sensors, one example of which is an EFPI sensor, that operates based on spectral interference. The system uses a two mode operation that includes a lower speed, accurate absolute measurement mode and a higher speed, relative measurement mode. The system achieves greater overall measurement accuracy and speed than known sensor interrogation approaches.

Abstract: A measurement system permits environmental, corrosion damage, and mechanical property measurements to assess protection properties of coatings. The system includes one or more multi-sensor panels, each multi-sensor panel having sensors for assessing coating barrier properties, free corrosion, and galvanic corrosion. Each multi-sensor panel is installed on a test rack that contains electronics for sensor excitation and sensor data acquisition throughout a corrosion test. Sensor data is collected, stored, and communicated to a base station. A network of multiple test racks can be supported by a base station to compare the performance of different coatings and material combinations simultaneously. The test racks can be used in accelerated atmospheric corrosion tests, outdoor test sites, or application service environments.

Abstract: A measurement system permits environmental, corrosion damage, and mechanical property measurements to assess protection properties of coatings. The system includes one or more multi-sensor panels, each multi-sensor panel having sensors for assessing coating barrier properties, free corrosion, and galvanic corrosion. Each multi-sensor panel is installed on a test rack that contains electronics for sensor excitation and sensor data acquisition throughout a corrosion test. Sensor data is collected, stored, and communicated to a base station. A network of multiple test racks can be supported by a base station to compare the performance of different coatings and material combinations simultaneously. The test racks can be used in accelerated atmospheric corrosion tests, outdoor test sites, or application service environments.

Abstract: Systems, methods, and structures for overcoming Rayleigh backscatter in wavelength division multiplexed fiber optic systems and in particular fiber optic sensor systems along with method(s) for detecting faults in optical networks employing the intentional temporal separation of share wavelength noise and demarcation signals in conjunction with the use of accumulated Rayleigh noise signal(s) to detect a fault location.

Abstract: An optical fiber includes primary optical core(s) having a first set of properties and secondary optical core(s) having a second set of properties. The primary set of properties includes a first temperature response, and the secondary set of properties includes a second temperature response sufficiently different from the first temperature response to allow a sensing apparatus when coupled to the optical fiber to distinguish between temperature and strain on the optical fiber. A method and apparatus interrogate an optical fiber having one or more primary optical cores with a first temperature response and one or more secondary optical cores with a second temperature response. Interferometric measurement data associated with each primary and secondary optical core are detected when the optical fiber is placed into a sensing position.

Abstract: The present disclosure relates to optical switching devices and switch modules that are designed for long-term security monitoring of high-value infrastructure access entry points. Embodiments in accordance with the present disclosure include optical switches based on fiber-Bragg gratings whose operating wavelengths are based on the presence or absence of magnetic coupling between an embedded permanent magnet and an external element. By monitoring the spectral position of the operating wavelengths and/or the magnitude of a light signal at the operating wavelengths, the state of the magnetic coupling can be determined and used as an indicator of whether the security switch has been actuated.

Abstract: An optical sensing fiber includes multiple reference reflectors spaced along a length of the fiber. Each of the multiple reference reflectors producing a reference scattering event having a known scattering profile including an elevated amplitude relative to scattering detected for neighboring segments of the optical fiber. Each of the segments is a length of contiguous fiber that is useable to initialize and perform a distributed Optical Frequency Domain Reflectometry (OFDR) sensing operation. An OFDR interrogation system is disclosed that measures a parameter using the optical sensing fiber.

Abstract: A sensor network having a series arrangement of fiber-coupled, reflective sensors is disclosed. In operation, a first light signal having multiple wavelength bands is launched in an upstream direction on a fiber bus. Each sensor includes a wavelength filter and an FP sensor that is sensitive to a parameter. Each wavelength filter (1) selectively passes a different one of the wavelength bands to its FP sensor and (2) reflects the remaining wavelength bands back into the fiber bus to continue upstream. The FP sensor imprints a signal based on the parameter onto its received light and reflects it as a second light signal. The collimator, wavelength filter, and FP sensor of each sensor are arranged such that each second light signal is returned to the fiber bus, which conveys them in a downstream direction to a processor that measures them and estimates the parameter at each sensor.

Abstract: A high-speed interrogation system is provided for interferometric sensors, one example of which is an EFPI sensor, that operates based on spectral interference. The system uses a two mode operation that includes a lower speed, accurate absolute measurement mode and a higher speed, relative measurement mode. The system achieves greater overall measurement accuracy and speed than known sensor interrogation approaches.

Abstract: Durable, transparent, inorganic-organic hybrid hydrophobic coating materials for glass, metal or plastic substrates are provided. The coating materials are generally an acid catalyzed condensation reaction product comprised of an organic polymeric silane (e.g., a polyol functionalized with a silane through a urethane linkage or a polyamine functionalized with a silane through a urea linkage, such as isocyanatopropyltrimethoxysilane or isocyanatopropyltriethoxysilane), an inorganic metal alkoxide (e.g., silicon alkoxides such as tetraethoxysilane or tetramethoxysilane) and a fluorinated silane (e.g., (3,3,3-trifluoropropyl)trimethoxysilane or nonafluorohexyltrimethoxysilane).

Abstract: A reactive hot melt (RHM) composition is provided as a mixture of a urethane prepolymer which is a reaction product of at least one crystallizable polyol, a perfluoropolyether polyol, and at least one isocyanate, a filler material, and a teachable plasticizer consisting of an aliphatic ester of a carboxylic acid.

Abstract: A sensing device includes a pair of contactless electrodes for placement on a coating on a surface of a structure or within or between one or more coatings on or over the surface of the structure. The electrodes function as sensors when activated to generate a current flow through the electrodes at multiple different frequencies. The sensing device also includes contactless control circuitry co-located with or separate from the electrodes that transmits impedance data generated from the activated electrodes. The impedance data is associated with corrosion condition information of the structure and/or the one or more coatings. A data collection system and display system useable with the sensing device are also described.

Abstract: Coating compositions which include a blend of a fluorochemical and a particulate additive comprising a bimodal size distribution of inorganic nanoparticles are provided. The bimodal distribution of inorganic nanoparticles may include a quantity of smaller nanoparticles having an average size distribution of between about 1 to about 15 nm, and a quantity of larger nanoparticles having an average size distribution of between about 40 to about 500 nm. The smaller and larger nanoparticles may be present in a ratio of the smaller sized particles to the larger sized particles of at least 1.2, with the total amount of nanoparticles being present in an amount of between about 0.1 to about 10 wt. % based on total composition weight.

Abstract: Medical training kits and methods include a simulated liquid blood which simulates mammalian whole blood and a simulated hemostatic component. The simulated liquid blood includes a gellable component, and a simulated hemostatic component includes a gelling agent. The gelling agent causes the gellable component in the simulated liquid blood to form a mass of semi-solid or solid material in response the simulated blood being brought into contact therewith to thereby simulate blood clotting. In certain embodiments, the gellable component is chitosan and/or an alginate compound and the gelling agent is at least one compound which causes the gellable component to desolubulize, polymerize, complex, precipitate, cross-link and the like so as to form a semi-solid or solid mass of chitosan in response to physical contact between the simulated blood and the simulated hemostatic agent.