New types of fiberoptic microbend sensors are in the form of flexible tapes wherein single or multiple layers of mechanically tough flexible tapes form two outside surfaces of the sensors including between them one or more continuous elongated optical fibers, a variety of monofilaments, wires, threads, meshes, ribbons and or like elements to act as deformers to the optical fiber and sufficient adhesive material to form a permanent flexible tape structure. Additional layers of film, optical fibers, and/or deformer elements may be included to augment or modify the intensity of light that issues from the output end of the optical fibers when they are illuminated at their input end while the surface films of the sensor are subjected to pressure, such as when the sensors are used to weight or detect passage of automobiles. Detection or measuring systems and methods using the flexible sensor tapes are disclosed.
A multi-layer sensor (10) and a use for the sensor (10) are described. This sensor is multi-layered in construction. 5 An optical wave guide (18) is passed through the sensor (10) such that in the event of an external application of force the force acts on the optical wave guide.
A hazard mitigation system to detect intrusion by an object into a track zone at a train station platform. A structure is provided that includes a fixed foundation and a surface layer that is cushionably placed above the foundation, such that the structure is located in the track zone. At least one sensor is mounted between the surface layer and the foundation. This sensor senses the weight of the object upon the surface layer and provides a sensor signal representative of that weight. A control unit receives the sensor signal, processes it to determine whether the object represents a potential hazard, and, if so generates a warning signal. The sensor can particularly include a strain or pressure gage, or a fiber optic sensor. When a fiber optic sensor is employed, it can particularly include a fiber Bragg grating.
A hazard mitigation system to detect an object in a highway-railway grade crossing. A structure is provided that includes a fixed foundation and a surface layer that is cushionably placed above the foundation, such that the structure is located between tracks at the crossing. At least one sensor is mounted between the surface layer and the foundation. This sensor senses the weight of the object upon the surface layer and provides a sensor signal representative of that weight. A control unit receives the sensor signal, processes it to determine whether the object represents a potential hazard, and, if so generates a warning signal. The sensor can particularly include a pressure or strain gage, or a fiber optic sensor. When a fiber optic sensor is employed, it can particularly include a fiber Bragg grating.
A flexible microbend device for attachment to an optical fiber is provided. The device comprises an upper bending element grid having at least one flexible element and a lower bending element grid having at least one flexible element. The upper bending element grid alternately engages the lower bending element grid. The flexible microbend device is attached to an optical fiber to form a sensor. The sensor may be either embedded in a host material or attached to a structure to detect various stresses or strains.
