Optical sensors having one or more soluble coatings thereon are used to detect the presence of a degrading fluid. In a generalized embodiment, the fiber optic sensor includes a fiber optic cable having two strain sensor positioned therein. A soluble layer is positioned over one of the strain sensor. Due to the presence of the soluble layer, the covered strain sensor optically responds differently than the other strain sensor to changes in pressure, strain and temperature. In the presence of a degrading fluid, the soluble layer degrades and ultimately dissolves, thereby changing the optical response of the previously covered strain sensor. When the soluble layer is dissolved, the strain induced by the soluble layer relaxes, thus causing a wavelength shift in the signal of the grating. By monitoring the wavelength shifts of both strain sensors, the fiber optic sensor acts as a detector for the presence of the degrading fluid.

A system for measuring subterranean physical properties, in some embodiments, comprises a source of broadband light, an input optical fiber coupled to the source of broadband light, a wavelength division demultiplexer coupled to the input optical fiber, a plurality of detectors arranged in parallel and coupled to the demultiplexer, a wavelength division multiplexer coupled to the plurality of detectors, and an output optical fiber coupled to the multiplexer.

A device for measuring force and for monitoring wear on overhead lines includes a force-measuring system which includes two contact bars which, in an operating state, are oriented at a right angle to an overhead line to be monitored, and two connection bars, which, in the operating state, are oriented parallel to the overhead line. A bar-shaped force transducer is fastened to each end portion of the two connection bars and each of the bar-shaped force transducers extends in an axial direction of the respective connection bar.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical cable structure is discussed that enables a distributed optical fiber sensor to detect acoustic vibration and other measurands, which could be, for example, changes in temperature, changes in static pressure, and changes in static strain. The optical cable structure includes first and second optical fibers disposed within a thin walled, elliptical, gel filled, loose tube helically wound within a cable wall of the optical cable structure. The optical cable structure further includes an additional optical fiber bonded to a strength member using a tight encapsulant. Because the additional optical fiber is fixed to the strength member and disposed with its axis parallel to the strength member, the additional optical fiber experiences the full axial strain on the optical cable structure, unlike the first and second optical fibers contained within the helically wound loose tube, thereby providing a contrast to the strain response coefficients of the first and second optical fibers.

Interferometric measurement signals are detected by a single optical interferometric interrogator for a length of a sensing light guide and an interferometric measurement data set corresponding to the interferometric measurement signals is generated. The interferometric measurement data set is transformed into a spectral domain to produce a transformed interferometric measurement data set. The transformed interferometric measurement data set is compared to a baseline interferometric data set to identify a time-varying signal corresponding to a time-varying disturbance. The baseline interferometric data set is representative of the sensing light guide not being subjected to the time-varying disturbance. A compensating signal is determined from the time-varying signal and used to compensate at least a portion of the interferometric measurement data set for the time-varying disturbance as part of producing a measurement of the parameter.

The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives and analyses light reflected from the polymer-based single-mode fibre-optic sensor system.