Disclosed are improved distributed optical fiber sensing systems, methods, and structures employing disparate point sensors that utilize uni-directional signal transmission via the distributed optical fiber such that a separate communications network for the disparate point sensors is not required.

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 acousticor vibrationor strain-dependent characteristics as a function of distance along the fiber link under test.

An optical cable (31) includes: a stress wave detection optical cable (30) having an optical fiber (7) and a plurality of first steel wires (8) which are helically wound so as to surround the optical fiber (7) and which are surrounded by a flexible material (9); and second steel wires (32) different from the first steel wires (8). The stress wave detection optical cable (30) and the plurality of second steel wires (32) are helically wound to form one annular body as a whole, and a winding angle () of the stress wave detection optical cable (30) with respect to the axis is determined by a property value prescribed by Lam constants of the flexible material (9).

This application relates to methods and apparatus for distributed fibre optic sensing and especially to the processing of signals derived from such sensing techniques to characterise events of interest. The application describes a method of distributed fibre optic sensing, comprising; performing distributed fibre optic sensing so as to generate at least one set of measurement signals from each of a plurality of sensing channels of an optical fibre (101) in response to at least one event of interest. For each set of measurement signals, processing the measurement signals from different sensing channels according to an association metric to determine whether any sensing channels are associated with one another and form at least one association matrix indicative of the sensing channels that are associated with one another. The method further comprising performing distributed fibre optic sensing to acquire a further set of measurement signals from said sensing channels in response to a further event of interest and processing said further set of measurement signals based on said at least one association matrix to characterise said further event of interest.

The present invention relates to a sensor device comprising an optical fiber to be coupled with a laser beam, a through-fiber fabricated cantilever onto one end of said optical fiber, and a light collector. According to the invention, the through-fiber fabricated cantilever is made of a polymer obtained by photo-structuring at least one photo-sensitive monomer species. The present invention also relates to methods for the measurement of parameters such as temperature, mass, viscosity, analyte concentrations, and the degree of a polymerization process, using the device of the invention.

An aspect of the invention is directed to a system of both atmospheric and underwater sensors for measuring pressure waves from a noise source. A system of pressure sensors can be formed to determine the location of an external noise source, whether in air or underwater. The system includes at least two arrays consisting of pressure sensors, including at least one atmospheric pressure sensor and at least one underwater pressure sensor, such as a hydrophone. Each sensor may be a seven-fiber intensity modulated fiber optic pressure sensor. The system includes an analog to digital converter for digitizing the pressure data received from each sensor and a processor which processes the received signals to calculate an approximate location of the noise source based upon the pressure signals received by the sensors at different times of arrival. The system can provide this capability in remote applications due to its low power requirements.

A seismic sensor for a seismic survey includes an outer housing having a central axis, a first end, and a second end opposite the first end. The first end comprises a portion made of a clear material configured to transmit light having a frequency in the visible or infrared range of the electromagnetic spectrum. In addition, the seismic sensor includes a proof mass moveably disposed in the outer housing. The proof mass includes a power source. Further, the seismic sensor includes a sensor element disposed in the outer housing and configured to detect the movement of the outer housing relative to the proof mass. Still further, the seismic sensor includes electronic circuitry coupled to the sensor element and the power source. The seismic sensor also includes a light guide assembly having a first end adjacent the clear portion of the first end of the outer housing and a second end adjacent the electronic circuitry. The light guide assembly is configured to transmit light in an axial direction between the first end of the light guide assembly the clear section and to transmit light in a non-axial direction between the second end of the light guide assembly and the electronic circuitry.

This application discloses a slope detection apparatus and method based on distributed optical fiber sensing. The apparatus includes: optical fiber measuring units arranged inside a slope and configured to measure acceleration time sequences of a plurality of state parameters of the slope; a demodulator, where the demodulator is connected to the optical fiber measuring units and configured to receive the acceleration time sequences of the slope; and a terminal device, where the terminal device is connected to the demodulator and configured to perform multi-domain coupling analysis on the acceleration time sequences so as to generate a feature cloud map of the slope, perform sub-item detection on slope stability state based on the feature cloud map and preset multi-domain feature parameter indexes so as to obtain a sub-item detection result of the state of the slope.

Disclosed are improved distributed optical fiber sensing systems, methods, and structures employing disparate point sensors that utilize uni-directional signal transmission via the distributed optical fiber such that a separate communications network for the disparate point sensors is not required.

Methods, systems, and techniques for determining whether an event has occurred from dynamic strain measurements involve determining, using a processor, at least one event parameter from a signal representing the dynamic strain measurements, and then having the processor use the at least one event parameter to determine whether the event has occurred. The at least one event parameter is any one or more of a measure of magnitude of the signal, frequency centroid of the signal, filtered baseline of the signal, harmonic power of the signal, and time-integrated spectrum flux of the signal.