The photo-acoustic conversion based sound emitter device has a sound output surface for transmitting sound wave vibrations to a medium outside the device. An optical waveguide, is used to transmit light through an optical path within the device. First and second photo-acoustic conversion volumes, at different distances from the sound output surface, are used for transmitting sound generated in the first and second volume to the medium via the sound output surface, the optical path extending directly or indirectly successively through the first and second photo-acoustic conversion volume. The device comprises an intermediate volume separating the first and second photo-acoustic conversion volumes along the optical path, the intermediate volume having a lower light absorption coefficient than the first and second photo-acoustic conversion volumes; and/or the first and second photo-acoustic conversion volume have a different cross-section area size and/or shape with virtual planes perpendicular to the optical path; and/or the first and second photo-acoustic conversion volumes have different optical absorption coefficients, or a different optical wavelength dependence of these optical absorption coefficients.

An optical fiber sensing range limiting device comprises: a blocking unit that, on the basis of a control signal and for a prescribed period, causes probe light that has been sent to an optical fiber used in optical fiber sensing and has returned from the optical fiber to be blocked from being transmitted to a light detection unit, or causes a detection signal that is detected with respect to the return light to be blocked from being transmitted to a downstream processing unit; and a control unit that outputs the control signal to the blocking unit. The prescribed period includes a period corresponding to the positional range for which acquisition of information from the detection signal is prohibited or for which it is undesirable to acquire the information.

A system includes an optical fiber provided in a monitor area, a detection unit that monitors the monitor area, a monitor, and a control unit that displays a monitoring situation of the monitor area on the monitor. The detection unit detects an anomaly that has occurred in the monitor area and identifies a location on the optical fiber where the anomaly is detected, based on a vibration pattern included in an optical signal received from the optical fiber. On the monitor, as a monitoring situation of the monitor area, the control unit displays an arrangement situation of the optical fiber in an overlapping manner on a map of the monitor area, displays a mark indicating a location on the optical fiber where the anomaly is detected, in an overlapping manner on the map of the monitor area, and displays information indicating a detail of the anomaly.

The present disclosure provides a method of processing data obtained from distributed optical fiber sensors to detect acoustic energy generated by a poroelastic effect of fractures in a structure, such as a rock formation. The sensing fiber of an optical fiber distributed sensing system may be deployed in the vicinity of the region where fracturing is occurring, for example, along a well that is offset from a treatment well undergoing hydraulic fracturing. The DAS data obtained from along the sensing fiber is processed to measure changes in the low-frequency strain caused by the poroelastic effects in the rock as the fractures open and close. This measured strain rate data is iteratively processed at each instant time to identify fracture opening features (characterised as compression-tension-compression) that are correlated with fracture closing features (characterised as tension-compression-tension) as a function of depth, to thereby identify and locate fracture hits in the vicinity of the sensing fiber.

A machine learning system and method are provided for using fiber-optic Distributed Acoustic Sensor (DAS) and Distributed Temperature Sensor (DTS) data to predict pressure along one or more optical fiber cables. DAS and DTS data are used to train a model to predict pressure based on the DAS and DTS data corresponding to optical signals carried on the fiber cable(s). The trained model is then used to process acquired DAS and DTS data corresponding to optical signals carried on the fiber cable(s) to the predict pressure distributed along the cable(s).

A sensor system includes a sensor network comprising at least one optical fiber having one or more optical sensors. At least one of the optical sensors is arranged to sense vibration of an electrical device and to produce a time variation in light output in response to the vibration. A detector generates an electrical time domain signal in response to the time variation in light output. An analyzer acquires a snapshot frequency component signal which comprises one or more time varying signals of frequency components of the time domain signal over a data acquisition time period. The analyzer detects a condition of the electrical device based on the snapshot frequency component signal.

A bearing ring having a main part ring provided with at least one groove formed a surface of the main part ring. The bearing ring further provides at least one fiber sensor mounted inside the groove. The bearing ring also include at least one counterpart ring mounted into the groove of the main part ring and coming into contact with the fiber sensor to maintain the fiber sensor against a groove bottom, the counterpart ring being secured to the main part ring.

The invention relates to the technical field of mechanical vibration measurement, and discloses a device for accurately measuring mechanical vibration by photon counter. The device comprises a laser, an optical isolator, an adjustable attenuator, an optical fiber coupler, a single-photon counter and an FPGA post-processing module, wherein the laser enters the optical fiber coupler after passing through the optical isolator and the adjustable attenuator, and then enters into a measured object. The transmitted signal of the object to be measured returns to the optical fiber coupler and is output to the single-photon counter; the mechanical vibration of the measured object is analysed and obtained by the FPGA post-processing module connecting with the output terminal of the single-photon counter. This invention solves the problem that weak mechanical vibration is difficult to measure, and realizes microscopic vibration measurement of light-permeable objects such as nanofiber cavities by using a single photon counter.

The invention relates to a measuring device (10) comprising aa measuring equipment (30) that is configured to be optically interrogated by a measuring instrument (20) by means of first optical signals in a first wavelength range, and a connecting optical fibre (100) for optically connecting aa measuring equipment (30) to a measuring instrument (20). The connecting optical fibre (100) comprises at least a first optical core (111) that is multimode in the first wavelength range and a second optical core (112) that is single-mode in a second wavelength range. The connecting optical fibre (100) comprises at least one first segment of functionalised optical fibre (120) that is such as to exhibit, at the second wavelength, an optical property that varies with an environmental parameter of the connecting optical fibre (100). The invention also relates to a measuring assembly and to an apparatus that comprises such a measuring assembly.

An optical fiber sensing system according to the present disclosure includes: an optical fiber (10) disposed to lie in a plurality of directions and configured to sense sound generated in a monitored area; a reception unit (20) configured to receive, from the optical fiber (10), an optical signal on which the sound is superimposed; and an identification unit (30) configured to analyze distribution of the sound sensed by the optical fiber (10) based on the optical signal and identify a generation position of the sound based on the analyzed distribution of the sound.