The invention discloses an underwater umbilical cable which is capable of temperature and vibration measuring and three-dimensional shape reconstruction, wherein underwater umbilical cable is used to connect underwater equipment and aquatic equipment; the underwater umbilical cable comprises an outer sheath, armored steel wires, an inner sheath, a power cable, a communication optical cable, a steel pipe, three strain measuring optical fibers, three temperature measuring optical fibers, a distributed optical fiber strain interrogator, a distributed optical fiber temperature interrogator and a processor. The invention can collect the operation status data of the umbilical cable for a long time. The collected data is highly objective, can truly reflect the real-time operation status of the umbilical cables, and plays an important role in guaranteeing the long-term submarine oil and gas exploitation.

Disclosed is a temperature and strain sensing optical fiber including a first doped radial zone (Z1) with an associated first Brillouin shift (BS1) caused by the doping of said zone (Z1) and a second doped radial zone (Z2) with associated second Brillouin shift (BS2) caused by the doping of said second zone (Z2). The concentration and/or composition of the doping materials in said first and second radial zones are chosen such that the first Brillouin Shift (BS1) is different from the second Brillouin Shift (BS2) for all variations of said Brillouin Shifts (BS1, BS2) caused by temperature and/or strain.

A system may include a sensing fiber that can receive interrogation data via a coil of reference fiber, the coil of reference fiber configurable to be of a same type of fiber as the sensing fiber, and the sensing fiber configurable to be coupled in series with the coil of reference fiber. A known temperature and a known strain can be received from the coil of reference fiber. The known temperature, the known strain, and the interrogation data can be outputted for calibrating a measurement of the interrogation data.

Distributions of a Brillouin frequency shift and a Rayleigh frequency shift in optical fibers set up in a material are measured from scattered waves of pulse laser light entered into the optical fibers, and distributions of pressure, temperature, and strain of the material along the optical fibers at a measurement time point are analyzed using coefficients that are inherent to the set up optical fibers and correlate pressure, temperature, and strain of material with the Brillouin frequency shift and the Rayleigh frequency shift.

Overheat and fire detection for aircraft systems includes an optical controller and a fiber optic loop extending from the optical controller. The fiber optic loop extends through one or more zones of the aircraft. An optical signal is transmitted through the fiber optic loop from the optical controller and is also received back at the optical controller. The optical controller analyzes the optical signal to determine the temperature, strain, or both experienced within the zones.

A measurement system includes a cable having a length, a light source, at least one detector, and at least one processor. The light source is operably coupled to the cable and is configured to transmit an optical signal to the cable. The at least one processor is operably coupled to the cable and configured to: receive a scattered signal from the cable responsive to the optical signal transmitted to the cable; map the scattered signal to the length of the cable; and de-convolve a spatial averaging effect of the scattered signal using a weighting profile corresponding to the light source and the cable to generate a distributed property profile defined along the length of the cable.

Overheat and fire detection for aircraft systems includes an optical controller and a fiber optic loop extending from the optical controller. The fiber optic loop extends through one or more zones of the aircraft. An optical signal is transmitted through the fiber optic loop from the optical controller and is also received back at the optical controller. The optical controller analyzes the optical signal to determine the temperature, strain, or both experienced within the zones.

Overheat and fire detection for aircraft systems includes an optical controller and a fiber optic loop extending from the optical controller. The fiber optic loop extends through one or more zones of the aircraft. An optical signal is transmitted through the fiber optic loop from the optical controller and is also received back at the optical controller. The optical controller analyzes the optical signal to determine the temperature, strain, or both experienced within the zones.

Overheat and fire detection for aircraft systems includes an optical controller and a fiber optic loop extending from the optical controller. The fiber optic loop extends through one or more zones of the aircraft. An optical signal is transmitted through the fiber optic loop from the optical controller and is also received back at the optical controller. The optical controller analyzes the optical signal to determine the temperature, strain, or both experienced within the zones.

According to examples, a Brillouin and Rayleigh distributed sensor may include a first laser source to emit a first laser beam, and a second laser source to emit a second laser beam. A photodiode may acquire a beat frequency between the two laser beams. The beat frequency may be used to maintain a predetermined offset frequency shift between the two laser beams. A modulator may modulate the first laser beam. The modulated first laser beam is to be injected into a device under test (DUT). A coherent receiver may acquire a backscattered signal from the DUT. The backscattered signal results from the modulated first laser beam injected into the DUT. The coherent receiver may use the second laser beam as a local oscillator to determine Brillouin and Rayleigh traces with respect to the DUT based on the predetermined offset frequency shift.