A railroad monitoring system according to the present disclosure includes a cable (20) including a communication optical fiber being laid on a railroad (10), a reception unit (331) configured to receive an optical signal from at least one communication optical fiber included in the cable (20), and a detection unit (332) configured to detect a pattern according to a state of the railroad (10), based on the optical signal, and detect an abnormal state of the railroad (10), based on the detected pattern according to the state of the railroad (10).

An optical monitoring system comprising first and second sensor arrays interrogated via first and second optical connections from an interrogator location. The system is configured such that no wavelength is carried bi-directionally in the first and second optical connections. In typical systems the optical connections comprise trunk cables from the sensor arrays to the interrogator location.

An apparatus is disclosed for capturing image information. The apparatus includes a waveguide having opposed planar input and output faces. A diffractive optical element (DOE) is formed across the waveguide. The DOE is configured to couple a portion of the light passing through the waveguide into the waveguide. The light coupled into the waveguide is directed via total internal reflection to an exit location on the waveguide. The apparatus further includes a light sensor having an input positioned adjacent the exit location of the waveguide to capture light exiting therefrom and generate output signals corresponding thereto. A processor determines the angle and position of the coupled light with respect to the input face of the waveguide based on the output signals.

A fiber optic sensing system for determining the position of an object requires a light source, an optical fiber, a fiber optic splitter, a fiber tip lens, an optical detector and signal processing circuitry. Light emitted by the light source is conveyed via optical fiber and the splitter to the lens and onto an object, such that at least a portion of the light is reflected by the object and conveyed via fiber and the splitter to the detector. Signal processing circuitry coupled to the detector determines the position of the object with respect to the lens based on a characteristic of the reflected light. The system is suitably employed with a hydraulic accumulator having a piston, the position of which varies with the volume of fluid in the accumulator, with the system arranged to determine the position of the piston, from which the volume can be calculated.

An optical sensor and method of manufacture are provided herein. The optical sensor includes an optical fiber comprising a terminating end surface, and a photonic crystal coupled to the terminating end surface of the optical fiber.

Generally, the present disclosure provides for a light duct sensor that can monitor an average light flux through light duct useful for architectural lighting. The present disclosure provides for a system that allows a minimally obtrusive sampling of the light in a duct. It samples a small fraction of a cross sectional area of a light duct that is distributed across potentially the entire cross sectional area, without creating a significant disturbance to the light.

The position detector of an object comprises a body defining an input receiving an optical fibre delivering a light signal, and an output delivering a signal representative of the position of the object. A mirror is mounted to move between first and second positions in the body with respect to the input. The first position or the second position ensures transmission of the light signal from the input to the output. The other of the first position and the second position prevents transmission of the light signal to the output. A spring is mounted in the body in order to place the mirror in the first position. A tip is movable relative to the body between a first position and a second position along a direction of movement and is intended to cooperate with the object to be monitored.

A system and method for seismic monitoring of large area subsurface reservoirs, for instance, the system comprising: multiple electro acoustic technology assemblies comprising seismic sensing elements, electronic circuits for converting the seismic sensing signals to frequencies, amplification circuitry to amplify the frequencies, an acoustic source that converts the amplified frequencies to an acoustic frequency signal; a fiber optic acoustic sensing system comprising a fiber optic cable deployed in a subsurface reservoir, where the multiple electro acoustic technology assemblies are proximate to and/or acoustic coupled with the fiber optic cable of the fiber optic acoustic sensing system, and a surface based distributed acoustic sensing interrogator connected to the fiber optic cable.

A system (10) includes an optical source, multiple coupler units (22), a controller (20), and a detector (123). The optical source is configured to transmit an optical signal into an optical cable (40). The multiple coupler units are coupled to the optical cable and are each configured to (i) accept one or more configuration parameters, (ii) receive data from one or more sensors (30), (iii) modulate the data onto an acoustical signal in accordance with the configuration parameters, and (iv) modulate a mechanical strain applied to the optical cable with the acoustic signal, so as to modulate the optical signal with the data. The controller is configured to coordinate and send the configuration parameters to the multiple coupler units. The detector is configured to receive the optical signal from the optical cable, and to demodulate the data that was modulated onto the optical signal by the multiple coupler units.

A waveguide for guiding an electro-magnetic wave comprises: a first waveguide part; and a second waveguide part; wherein the first waveguide part has a first width in a first direction (Y) perpendicular to the direction of propagation of the electro-magnetic wave and the second waveguide part has a second width in the first direction (Y), wherein the second width is larger than the first width; and wherein the first and the second waveguide parts are spaced apart by a gap in a second direction (Z) perpendicular to the first and second planes in which the waveguide parts are formed, wherein the gap has a size which is sufficiently small such that the first and second waveguide parts unitely form a single waveguide for guiding the electro-magnetic wave. The waveguide may be used in numerous applications, such as in a photonic integrated circuit, in a sensor or in an actuator.