An optical fiber sensor system and method for monitoring a condition of a linear structure such as a pipeline is provided which is capable of providing continuous monitoring in the event of a break in the sensing optical fiber or fibers. The system includes at least one sensing fiber provided along the length of the linear structure, and first and second interrogation and laser pumping sub-systems disposed at opposite ends of the sensing fiber, each of which includes a reflectometer. The reflectometer of the first interrogation and laser pumping sub-system is connected to one end of the sensing fiber. The reflectometer of the second interrogation and laser pumping sub-system is coupled to either (i) an end of a second sensing fiber provided along the length of the linear structure which is opposite from the one end of the first sensing fiber, or (ii) the opposite end of the first sensing fiber. Before any break of the sensing fiber or fibers occurs, each reflectometer redundantly monitors the condition of the linear structure over its entire length. After any such break occurs, each reflectometer will continue to receive signals up to the point of the break from opposite ends of the structure.

Embodiments of the invention provide a method of determining one or more characteristics of a target object, comprising recording one or more diffraction patterns at a detector, wherein each diffraction pattern is formed by a target object scattering incident radiation, determining a phase map for at least a region of the target object based on the one or more diffraction patterns, and determining a refractive property of the target object based on the phase map.

Embodiments of the invention provide a method of determining one or more characteristics of a target object, comprising recording one or more diffraction patterns at a detector, wherein each diffraction pattern is formed by a target object scattering incident radiation, determining a phase map for at least a region of the target object based on the one or more diffraction patterns, and determining a refractive property of the target object based on the phase map.

An optical encoder of the present invention includes a light-receiving element unit 5, moving slit 2 and fixed slit 3. The light-receiving element unit 5 includes a pattern 5B for detecting infiltration of liquid.

This application relates to methods and apparatus for fiber optic sensing which can provide information about the environment in which the fiber optic is deployed. In particular the application relates to fiber optic based sensing of the mechanical impedance of the environment. The method comprises using an interrogator (201) to interrogate an optical fiber (104) which is coupled to a first element (202; 802) which is responsive to electromagnetic fields. In use a varying electric current (I), which may be an alternating current, is applied so as to induce a varying force (F) on said first element. The optical radiation backscattered from within the optical fiber is analyzed to determine a measurement signal indicative of a variation in the backscattered radiation corresponding with said electric current applied. The first element may be a first conductor (202) and the varying current may be supplied to the first conductor, or to a second conductor (701). Alternatively the first element could be a magnetic element (802). By applying a variable force to the first element, and hence the optical fiber, the characteristics of the environment can be determined.

A machine arrangement, including at least one bearing ring, wherein a glass fiber is connected with the machine arrangement. To allow a proper measurement of stresses, even at curved surfaces of the machine arrangement as it is typical in the case of bearing rings, the connection between the glass fiber and the machine arrangement is established by a glass material. The glass material is connected by material bonding with the machine arrangement as well as with the glass fiber.

An optical sensor (100) comprises: a holding sleeve (11); a fixed ferrule (12) fixedly mounted in said holding sleeve (11); a movable ferrule (13) movably mounted in said holding sleeve (11), a predetermined distance existing between a first movable end of said movable ferrule (13) and a first fixed end of said fixed ferrule (12) in said holding sleeve (11); a reflection part (14) arranged at a second movable end of said movable ferrule (13) opposite to said first movable end, for reflecting light entering the movable ferrule (13); and an actuation part (15), said actuation part (15) being constructed to drive said movable ferrule (13) to move so that said first movable end moves towards said first fixed end. An optical sensor assembly and a monitoring device comprising the optical sensor (100), or another sensor (1012) can remotely detect a mechanical movement in a passive mode. A first reflector (14, 1016) is configured to provide a first reflected optical signal. The sensor (100, 1012) is connected to the first reflector and has a first position and a second position, the second position configured to attenuate the first reflected optical signal more than the first position. The sensor is configured to move between the first and second positions in response to a monitored parameter (1018).

A portable inspection probe for the inspection of a recessed mating surface of an optical fiber connector is provided. In one variant, the portable inspection probe includes a digital holographic detection module operable to digitally record a hologram of the recessed mating surface, and a rigid probe tip configured to be optically coupled to the digital holographic detection module and shaped to provide optical access to the recessed mating surface. In another variant, the portable inspection probe is to be used with a rigid probe tip connectable thereto, and the digital holographic detection module includes a probing optical assembly not traversed by a reference beam and configured to direct an object beam onto the recessed mating surface and to collect the object beam upon reflection thereof by the recessed mating surface. An inspection system and an inspection method are also provided.

The disclosed technology includes, among others, methods and devices for measuring distributed fiber bend or stress related characteristics along an optical path of fiber under test (FUT) uses both a light input unit and a light output unit connected to the FUT at one single end.

A drilling optimization collar for use proximate a drilling tool within a wellbore includes a fiber optic sensor filament that is sized and configured to fit within a groove formed within the drilling optimization collar. The drilling optimization collar may be a pipe segment that is sized and configured to be installed in a drill string proximate the drilling tool, and may have a plurality of sensor elements. All or a portion of the sensor elements may be formed by discrete segments of the sensor filament, and as such, the sensor filament includes sensor elements that are configured to sense a condition of the wellbore and a load on the drilling optimization collar.