A system and method for evaluating individual Fiber Bragg Grating (FBG) sensors in a multiplexed acoustic sensor system, the system comprising: a broadband pulsed source; a circulator that passes a laser pulse to a multiplexed series of N FBG sensors and one reference Fresnel reflector, wherein said circulator also receives a return N+1 reflection pulse train from the N FBG sensors and one reference Fresnel reflector; and an optical switch that receives the return N+1 reflection pulse train from the N FBG sensors and one reference Fresnel reflector.

An optical shape sensing method is provided. The method comprises: providing first and second optical fibre portions arranged to receive light from at least one common lasers such that a path length of the light from the laser to the first optical fibre portion differs from a path length of the light from the lasers to the second optical fibre portion by a first distance; wherein the first and second optical fibre portions are spaced apart from each other in a first direction; and wherein the first and second optical fibre portions comprise a plurality of reflectors spaced along the length of the optical fibre portions, wherein the reflectors are arranged in sets of reflectors, each set including one reflector from each of the optical fibre portions, wherein the reflectors in each set are aligned with one another in a second direction that is perpendicular to the first direction when the optical fibre portions are in neutral positions; supplying light from the laser to the optical fibre portions; detecting an interferometric signal from the optical fibre portions at a common detector; determining, for each set of reflectors, optical path length differences between the reflectors in the set of reflectors based on the detected interferometric signal; determining a curvature of the optical fibre portions in the first direction based on the optical path length differences, between the reflectors in the first and second optical fibre portions, for the sets of reflectors. An optical shape sensor and optical shape sensing system are also provided.

A method is provided for determining temperature changes of an optical fibre having Fiber Bragg Grating (FBG) patterns provided in at least one portion (Portion 1) of the optical fibre. The optical fibre is connected between a first detector arrangement and a second detector arrangement. Light is emitted into the optical fibre in a first direction from the first detector arrangement, which receives reflections from the FBG patterns of the emitted light. The reflections are processed for determining a current temperature change related to the optical fibre. On the basis of predetermined criteria, light is emitted into the optical fibre in an opposite second, direction from the second detector arrangement. The second detector arrangement receives reflections from the FBG patterns of the light emitted in the second direction and the reflections are processed for determining a current temperature change related to the optical fibre.

A system for detecting an intrusion of at least one of a monitoring fiber and a detector comprises a sensor having a closure monitor and an intrusion monitor, the closure monitor including a signal generator and at least one detector attached to the monitoring fiber. The signal generator transmits signal light such that the monitoring fiber receives the transmitted signal light and reflects a portion of the signal light via the at least one detector to the closure monitor and transmits a non-reflected portion of the signal light. The intrusion monitor receives the transmitted non-reflected portion of the signal light, and monitors the non-reflected portion of the signal light to detect transient changes in the non-reflected portion of the signal light indicative of at least one of a vibration, a motion and a handling of at least one of the monitoring fiber and the at least one detector.

A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

The invention relates to a method for determining temperature changes of an optical fibre (250) having Fiber Bragg Grating (FBG) patterns provided in at least one portion (Portion 1) of said optical fibre (250), said optical fibre (250) being connected between a first detector arrangement (210) and a second detector arrangement (220), the method comprising the steps of: emitting (s410) light into said optical fibre (250) in a first direction (D1) from said first detector arrangement (210), receiving reflections from said (FBG) patterns of such emitted light by said first detector arrangement (210), and processing said reflections for determining a current temperature change related to said optical fibre (250); on the basis of predetermined criteria, emitting (s440) light into said optical fibre (250) in an opposite, second, direction (D2) from said second detector arrangement (220), receiving reflections from said (FBG) patterns of such emitted light by said second detector arrangement (220), and processing said reflections for determining a current temperature change related to said optical fibre (250). The invention relates also to a computer program product comprising program code (P) for a computer (233; 243; 253; 500) for implementing a method according to the invention. The invention relates also to a system (289) for determining temperature changes of an optical fibre (250). The invention also relates to a platform (100) being equipped with the system (289).

The disclosure concerns a device (101) for distributed sensing comprising: a pump generator (1) for generating an optical pump signal, a pump splitter (2) configured to split the pump signal in a number N of channels (3), each channel comprising an optical fiber (31) or a connector (32) arranged for connecting an optical fiber, a controller configured to control the pump splitter, an optical receiver (4) for receiving a backscattered signal from the optical fiber or from the connector of each channel. The pump splitter comprises a gating system comprising a gate (21) for each channel among the N channels. Each gate is associated to a given channel and has an open state allowing the pump signal to go from the pump generator to the optical fiber or the connector of the associated channel, and a closed state for which the pump signal cannot go from the pump generator to the optical fiber or the connector of the associated channel.

A sensor system for detection and localisation of changes in or values for at least one environmental condition includes a source of pulses of electromagnetic radiation, wherein the source is configured to emit electromagnetic radiation at a plurality of different wavelengths, an optical fibre in optical communication with the source of pulses, wherein the optical fibre includes a fibre Bragg grating having a reflectance and/or transmittance which varies in dependence on the at least one environmental condition, and a detection unit for detecting electromagnetic radiation which has been reflected or transmitted by the fibre Bragg gratings, wherein the detection unit is configured for detecting electromagnetic radiation at the plurality of wavelengths, such that a spectral response can be determined for different spatial regions along the optical fibre, wherein a change in or value for the environmental condition at a spatial region may be determined by monitoring the respective spectral response.

The invention relates to a method for determining temperature, pressure, strain, or other changes of an optical fibre (250) having Fiber Bragg Grating (FBG) patterns provided in at least one portion (Portion 1) of said optical fibre (250), said optical fibre (250) being connected between a first detector arrangement (210) and a second detector arrangement (220), the method comprising the steps of:

emitting (s410) light into said optical fibre (250) in a first direction (D1) from said first detector arrangement (210), receiving reflections from said (FBG) patterns of such emitted light by said first detector arrangement (210), and processing said reflections for determining a current temperature change related to said optical fibre (250);

on the basis of predetermined criteria, emitting (s440) light into said optical fibre (250) in an opposite, second, direction (D2) from said second detector arrangement (220), receiving reflections from said (FBG) patterns of such emitted light by said second detector arrangement (220), and processing said reflections for determining a current temperature change related to said optical fibre (250).

The invention relates also to a computer program product comprising program code (P) for a computer (233; 243; 253; 500) for implementing a method according to the invention. The invention relates also to a system (289) for determining temperature changes of an optical fibre (250). The invention also relates to a platform (100) being equipped with the system (289).

A system for detecting an intrusion of at least one of a monitoring fiber and a detector comprises a sensor having a closure monitor and an intrusion monitor, the closure monitor including a signal generator and at least one detector attached to the monitoring fiber. The signal generator transmits signal light such that the monitoring fiber receives the transmitted signal light and reflects a portion of the signal light via the at least one detector to the closure monitor and transmits a non-reflected portion of the signal light. The intrusion monitor receives the transmitted non-reflected portion of the signal light, and monitors the non-reflected portion of the signal light to detect transient changes in the non-reflected portion of the signal light indicative of at least one of a vibration, a motion and a handling of at least one of the monitoring fiber and the at least one detector.