An apparatus has a chassis having a base. A first wall extends substantially perpendicularly from the base at a first edge of the base. The first wall is configured to be a first attachment point for an optical cable comprising one or more optical sensors. An opposing second wall extends substantially perpendicularly from the base at a second edge of the base. A mobile attachment point is configured to be a second attachment point for the optical cable. A spring is coupled to the second wall and the mobile attachment point. The spring is configured to provide a specified force as the mobile attachment point moves.

A fibre optic cable structure (300) suitable for fibre optic sensing with an improved sensitivity to an environmental parameter is described. The structure (300) includes an optical fibre (301) and a bend inducer (304) responsive to the environmental parameter to control bending of the optical fibre. The bend inducer (304) is configured to adopt a first configuration, that induces a first curvature of the optical fibre, at a first value of the environmental parameter and to adopt a second configuration at a second, different, value of the environmental parameter that induces a second, different, curvature of the optical fibre. By action of the bend inducer (304) a change in value of the environmental parameter imparts a bending force on the optical fibre.

An extended length of optical fiber having an offset core with an inscribed Bragg grating is used a distributed sensor in combination with an optical frequency domain reflectometer (OFDR) to enable measurement small-scale (e.g., sub-millimeter) contortions and forces as applied to the fiber. The offset core may be disposed in a spiral configuration around the central axis of the optical fiber to improve the spatial resolution of the measurement. A reference surface exhibit a predetermined texture (in the form of a series of corrugations, for example, that may be periodic or aperiodic, as long as known a priori) is disposed adjacent to a longitudinal portion of the sensor fiber. The application of a force to the combination of the plate and the fiber creates a local strain in the grating formed along the offset core of the fiber that results in a shift in the Bragg wavelength of the grating. Using ODFR measurement techniques, an analysis of the Bragg wavelength shift allows for a high resolution force measurement to be obtained.

An apparatus has a chassis having a base. A first wall extends substantially perpendicularly from the base at a first edge of the base. The first wall is configured to be a first attachment point for an optical cable comprising one or more optical sensors. An opposing second wall extends substantially perpendicularly from the base at a second edge of the base. A mobile attachment point is configured to be a second attachment point for the optical cable. A spring is coupled to the second wall and the mobile attachment point. The spring is configured to provide a specified force as the mobile attachment point moves.

Accelerometer for measuring acceleration along a measurement direction including a moving mass which is moving with respect to a frame member only along the measurement direction, a suspension system for suspending the moving mass in the frame member while substantially limiting movement of the moving mass along only the measurement direction, and an optical fibre that is connected at a fibre connection point that is coupled to the movable mass. The optical fibre is arranged between the moving mass and the frame member and includes a measurement section for measuring the movement of the moving mass along the measurement direction.

An apparatus includes an electronic circuit, an electro-acoustic transducer and a coupler. The electronic circuit is configured to receive data to be transmitted over an optical cable, and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is configured to be mechanically coupled to a section of the optical cable, and to apply to the section a longitudinal stretching force that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.

A data telemetry system and method digitizes acoustic sensor data. Acoustic sensor data is digitized and used to apply strain to a series of Fiber Bragg Gratings (FBGs) in a fiber. Each FBG is assigned a nominal wavelength. A wavelength interrogator launches wavelengths into the fiber and scans the reflected wavelengths from the FBGs. A data telemetry rate of at least 5 kHz may be achieved. Acoustic sensors may be part of undersea acoustic sensing arrays with large element counts having reduced system cabling and improved Size, Weight and Power (SWaP). The system and method realizes low power loss per array element and efficient multiplexing of many data streams in a small form factor.

One or more spacers for installing an optical cable are disposed in a trench that extends along an axis. The optical cable includes one or more optical sensors. Each spacer includes a base configured to rest in a bottom of the trench. A first arm extends from the base. The first arm is adjacent to a first wall of the trench. An opposing second arm extends from the base. The second arm is adjacent to an opposing second wall of the trench. The optical cable is configured to extend along the axis.

The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and for a device that is contiguously engaged with a surface of the substrate, includes the substrate embedded in the device, or includes the surface of the substrate at a predetermined distance from the device, a thermal and/or a mechanical property associated with the device, or a radiation level associated with a device environment.