Abstract: An object is to provide an optical fiber path search method, an optical fiber path search system, a signal processor, and a program that can be operated free of the effects of walls, supporting members, and the like so that only a signal generated by an acoustic wave propagating through the air can be extracted.

Abstract: The present disclosure is an optical line test system that detects a distribution of loss points of an optical line in a longitudinal direction, using a coherent light measurement device, applies vibration to facility disposed on a path of the optical line, detects a vibration point of the optical line in a longitudinal direction upon applying the vibration, using the coherent light measurement device, and identifies the loss point based on correspondence between the detected loss point and vibration point.

Abstract: It is intended to provide a phase measurement method and a signal processing device that are capable of reducing influence of noise of a measuring device without increasing the peak intensity of an incident light pulse when measuring the phase of scattered light in DAS-P.

Abstract: A vibration detection method is presented to accurately detect vibration physically applied to an optical fiber, using a simple determination reference. In a vibration detection method, scattered light of a given target segment of a measurement target fiber is indicated by vectors of an in-phase component and a quadrature component, and a triangular shape constituted by a near-end-side vector of the target segment and a far-end-side vector is used as a physical amount to be tracked. That is, it is determined whether or not there is vibration based on a change in shape of the triangular shape with respect to a reference state. This is a detection method in which DAS-I and DAS-P are combined, a simple determination reference such as shape change of a triangular shape is employed, and overlooking of vibration detection can be reduced.

Abstract: An object is to provide a vibration detection apparatus and a vibration detection method which can avoid occurrence of a point where detection sensitivity deteriorates in vibration detection of a scattered light intensity monitor according to optical frequency multiplexing. The present invention conceives a multi-dimensional space having as many dimensions as the number of frequencies to be used, causes scattered light intensity change at each optical frequency to correspond to each axis, plots a scattered light signal as a vector on the space, performs linear approximation passing through an origin on the space having a plurality of plotted vector points as original data, and performs vibration detection using a direction vector of an approximate straight line obtained as a result of the approximation.

Abstract: An object of the present disclosure is to provide a method and an apparatus for acquiring curvature and torsion using an inexpensive sensor medium. Disclosed is a measurement apparatus including a fiber ribbon including a plurality of coated fibers arranged in parallel, a strain measurement unit that measures strain amounts of the plurality of coated fibers, and an arithmetic processing unit that calculates curvature and torsion of the fiber ribbon using a strain amount of a coated fiber arranged in a middle portion of the plurality of coated fibers and a strain amount of a coated fiber arranged in a marginal portion of the plurality of coated fibers.

Abstract: A light intensity distribution measurement apparatus is presented that is capable of accurately measuring the intensity of light in each mode at each position of an optical fiber through which light is propagated in a plurality of modes.

Abstract: An object of the present disclosure is to measure, at a high sampling rate, a distribution of a vibration pattern applied to each core after being branched.

Abstract: An object is to provide an optical fiber route search method, an optical fiber route search device, and a program that can efficiently confirm a path of an optical fiber that is installed over a long distance or across a large range. The optical fiber route search method according to the present invention carries out optical measurement that performs distributed measurement of the state of an optical fiber while applying a disturbance to the optical fiber in a portion in which wires of the optical fiber are parallel to each other, branch out, or intersect with each other (a proximity portion), and determines that the position in which the number of singularities (peaks or intensity fluctuations) fluctuates (becomes plural) is the position of the proximity portion from a distribution diagram obtained through the optical measurement.

Abstract: This disclosure describes inputting pulsated pump light in a fundamental mode or a first higher-order mode into one end of an optical fiber under test constructed by connecting two optical fibers in series; inputting probe light having an optical frequency difference within a Brillouin frequency shift range with respect to the pump light into the other end of the optical fiber under test in the fundamental mode or the first higher-order mode; measuring a Brillouin gain distribution related to a distance of transmitted light intensity of probe light output from the one end into which the pump light was input; and calculating each inter-modal coupling efficiency at the connection point of the optical fiber under test.

Abstract: An object of the present invention is to propose a design method of a minimum value N of the number of multiplexed frequencies that is necessary for measuring an object vibrational frequency according to DAS-P while taking into consideration a trade-off between a measurement distance and an upper limit of a measurable vibrational frequency. When a phase change of an arbitrary section of a measured optical fiber is represented by A×sin (2?fvt), N=4Zfv/? is satisfied when A is smaller than ?/2 but N=2Zfv/(?·Arcsin (?/2A)) is satisfied when A is equal to or larger than ?/2, where fv represents vibrational frequency, t represents time, Z represents a length of the measured optical fiber (a measurement distance), and ? represents the speed of light inside the measured optical fiber.

Abstract: An object of the present disclosure is to provide a method and an apparatus for acquiring curvature and torsion using an inexpensive sensor medium. Disclosed is a measurement apparatus including a fiber ribbon including a plurality of coated fibers arranged in parallel, a strain measurement unit that measures strain amounts of the plurality of coated fibers, and an arithmetic processing unit that calculates curvature and torsion of the fiber ribbon using a strain amount of a coated fiber arranged in a middle portion of the plurality of coated fibers and a strain amount of a coated fiber arranged in a marginal portion of the plurality of coated fibers.

Abstract: It is an object to enable offline measurement with a high SN ratio of the phase of scattered light of an optical fiber to be measured in an optical receiving system for real-time measurement (direct measurement). The phase measurement method according to the present invention performs coherent detection of scattered light using a 90-degree optical hybrid, obtains an estimated quadrature component value by averaging a measured quadrature component value that is directly measured and a calculated quadrature component value obtained by Hilbert transforming a measured in-phase component value that is directly measured, obtains an estimated in-phase component value by averaging the measured in-phase component value and a calculated in-phase component value obtained by inverse Hilbert transforming the measured quadrature component value, and calculates the phase of scattered light based on the estimated quadrature component value and the estimated in-phase component value.

Abstract: An object of the present disclosure is to enable each inter-modal coupling efficiency at a connection point between few-mode optical fibers to be accurately acquired.

Abstract: An object is to provide a light intensity distribution measurement method and a light intensity distribution measurement apparatus that are capable of accurately measuring the intensity of light in each mode at each position of an optical fiber through which light is propagated in a plurality of modes.

Abstract: It is intended to provide a phase measurement method and a signal processing device that are capable of reducing influence of noise of a measuring device without increasing the peak intensity of an incident light pulse when measuring the phase of scattered light in DAS-P.

Abstract: A stimulated Raman scattering microscope device is configured to irradiates a sample with a first optical pulse at a first repetition frequency, to irradiate the sample with a second optical pulse of an optical frequency different from an optical frequency of the first optical pulse at a second repetition frequency, and to detect optical pulses of the first repetition frequency that are included in detected light from the sample irradiated with the first optical pulse and the second optical pulse, as a detected optical pulse train. The second optical pulse is generated by dispersing predetermined optical pulses that include lights of a plurality of optical frequencies, regulating to output optical pulses of a predetermined number of different optical frequencies out of the dispersed optical pulses at the second repetition frequency, and coupling the regulated optical pulses.

Abstract: It is intended to provide a phase measurement method and a signal processing device that are capable of reducing influence of noise of a measuring device without increasing the peak intensity of an incident light pulse when measuring the phase of scattered light in DAS-P.

Abstract: The present invention aims to provide a vibration detection method, a signal processing device, and a program according to which it is possible to accurately detect vibration physically applied to an optical fiber, using a simple determination reference. In a vibration detection method according to the present invention, scattered light of a given target segment of a measurement target fiber is indicated by vectors of an in-phase component and a quadrature component, and a triangular shape constituted by a near-end-side vector of the target segment and a far-end-side vector is used as a physical amount to be tracked. That is, it is determined whether or not there is vibration based on a change in shape of the triangular shape with respect to a reference state. This is a detection method in which DAS-I and DAS-P are combined, a simple determination reference such as shape change of a triangular shape is employed, and overlooking of vibration detection can be reduced.

Abstract: An object is to provide an optical fiber route search method, an optical fiber route search device, and a program that can efficiently confirm a path of an optical fiber that is installed over a long distance or across a large range. The optical fiber route search method according to the present invention carries out optical measurement that performs distributed measurement of the state of an optical fiber while applying a disturbance to the optical fiber in a portion in which wires of the optical fiber are parallel to each other, branch out, or intersect with each other (a proximity portion), and determines that the position in which the number of singularities (peaks or intensity fluctuations) fluctuates (becomes plural) is the position of the proximity portion from a distribution diagram obtained through the optical measurement.