A non-contact photoacoustic spectrophotometry system is configured to measure an absorption spectrum of a material. The system includes a modulated light source such as tunable pulsed laser that generates laser pulses to produce photoacoustic signals in the material. A non-contact detector monitors the surface of the container for the material. The detector includes a second light source, such as a continuous wave laser, focused on the surface of the container, and transmits reflected light to an interferometer, for example, a Sagnac interferometer. The interferometer produces an interference signal from the received light that is proportional to the acoustic pressure, which is transmitted to a computer to calculate an absorption coefficient. Using a plurality of wavelengths from the tunable pulsed laser, an absorption spectrum may be generated.

A method for estimating an environmental parameter includes transmitting a first interrogation signal into an optical fiber, receiving a reflected return signal including light reflected from one or more of the plurality of FBG's in the fiber and receiving at a processor data describing the reflected return signal. The received data is comparted to expected data to determine a shift in wavelength of light reflected for one or more of the plurality of FBGs and a change in a length of a dead zone of the optical fiber based on the comparison is also determined. From this, estimates of locations two or more of the plurality of FBG's are formed.

A sensor positioning device, having a holding module, with a sensor receptacle, fastening element and spring element, the sensor receptacle being mounted movably relative to the fastening element along a compensating axis. The spring is arranged between the fastening element and the sensor receptacle to cooperate therewith, to create a restoring force during movement of the receptacle relative to the fastening element. A measurement connector with an abutment is configured for arrangement onto a process container, and is configured for releasable arrangement on the holding module. The sensor positioning device is configured such that, when the measurement connector is arranged on the holding module, the sensor receptacle is movable relative to the fastening element along the axis, and a pressing force of the sensor receptacle onto the abutment of the measurement connector is created by the spring. A sensor unit, for turbidity measurement, is provided having the sensor positioning device.

A utility pole deterioration detection system includes a cable (20) disposed in a utility pole (10), the cable (20) containing a communication optical fiber, a receiving unit (331) configured to receive an optical signal containing a pattern that changes according to a deterioration state of the utility pole (10) from at least one optical fiber contained in the cable (20), and a detection unit (332) configured to detect a deterioration state of the utility pole (10) based on the pattern.

Devices and methods for performing frequency domain (FD) fluorescence lifetime spectroscopy are provided. The devices include a modulated light source, a focusing optical fiber, a detecting optical fiber, and a detector. The methods include focusing sinusoidal modulated incident light from a light source on a biological sample containing a protein, detecting a range of wavelengths of sinusoidal modulated fluorescent light emitted from the protein, determining a phase shift for the modulated fluorescent light, determining an amplitude modulation of the modulated fluorescent light, and determining a fluorescence lifetime of the protein.

A method and a device for analyzing a structure by tomography and diffuse acousto-elastic field correlation are provided. An optical fiber comprising a plurality of measurement points of FBG (Fiber Bragg Grating) type, comprising sensors of Bragg grating type, is deployed in or on the structure to be analyzed. The method comprises the emission of light, into the optical fiber, and the measurement by correlation for each pair of FBG sensors. In a development, a prior imaging of the structure is performed by reconstruction of the velocities of propagation. Other developments comprise: the determination of the positions of the FBG sensors, the calibration of the tomography, the rosette configuration of the sensors forming the measurement points, the use of a plurality of optical fibers, of multiplexers, of lasers, of optical circulators, of omnidirectional optical sensors, of active noise sources, such as piezoelectric transducers, incorporated or not in the structure.

A self-referencing localized plasmon resonance sensing device and a system thereof are disclosed. The reference optical waveguide element is modified with a noble metal nanoparticle layer. The sensing optical waveguide element is modified with a noble metal nanoparticle layer, which is further modified with a recognition unit. The incident light is guided into the reference and the sensing optical waveguide elements to respectively generate localized plasmon resonance sensor signals. The reference and the sensing optical waveguide elements respectively have a calibration slope. The processor utilizes the calibration slopes to regulate the second difference generated by detecting with the sensing optical waveguide element. The processor utilizes a difference between the first difference, which is generated by detecting with the reference optical waveguide element, and the regulated second difference to obtain a sensor response.

According to one implementation, a damage detection system includes optical paths, a light source, a photodetector, and a signal processing system, a signal processing system. The optical paths propagate lights in at least three different directions. The optical paths have at least two paths per one direction. The light source makes the lights incident on one ends of the optical paths respectively. The photodetector detects the lights output from other ends of the optical paths. The signal processing system specifies at least one location of damage based on optical detection signals detected by the photodetector.

A multipoint detection fiber sensor including a plurality of sensing parts at a plurality of positions is provided. The sensing parts are able to detect curve amounts respectively. The multipoint detection fiber sensor includes a plurality of optical fibers arranged in an overall effective detection area that is an extent in which the multipoint detection fiber sensor detects curve amounts. Each of the optical fibers includes the plurality of sensing parts. The multipoint detection fiber sensor also includes a light source which supplies light to the optical fibers and a light receiver which receives light emitted through the optical fibers to which light is supplied. Furthermore, an insertion apparatus into which the multipoint detection fiber sensor is incorporated is provided.

Disclosed is an optical system for monitoring a parameter, such as a density or a pressure, of a fluid, in particular a gas or a mixture of gases, in a hollow core of an optical fiber, wherein the optical system comprises: an optical fiber which comprises a hollow core that is filled with a fluid, a pulsed laser for providing pulsed laser light, which is input into a first end of the optical fiber such that the laser light propagates through the hollow core from the first end to a second end of the fiber, wherein the pulsed laser light is configured to induce nonlinear processes by interacting with the fluid in the hollow core, and wherein the optical system further comprises a monitoring device for detecting acoustic vibrations in the fiber and for determining a parameter of the fluid based on the acoustic vibrations.