Distributed optical fiber sensing method and device for random code external modulation

Abstract

A random code external modulation distributive-type optical-fiber sensing method comprises the following steps of dividing a beam of continuous laser with the linear width being smaller than or equal to 100kHz into two paths of light after being externally modulated to be random-code laser, wherein one path of the light is used as reference light, and the other path is used as detection light to be transmitted to a sensing optical fiber; and adopting a correlation method to process Brillouin scattered light and reference light, which are scattered backwards by the sensing optical fiber, after being converted to an electric signal, and acquiring the information containing the temperature variation and stress distribution in the optical fiber to be measured. A random code external modulation distributive-type optical-fiber sensing device comprises a laser transmitting device, and a light splitting device, a detection optical fiber device, a photoelectric conversion device and a signal collection processing display device, which are arranged on a light emitting path of the laser transmitting device. Due to the adoption of the random code external modulation distributive-type optical-fiber sensing method and device, contradiction among the positioning precision, temperature and stress measuring precision of the existing distributive-type optical-fiber sensor can be solved, and long-distance and high-resolution temperature and stress measurement can be realized.

Description

technical field [0001] The invention relates to an optical fiber sensor, in particular to a distributed optical fiber sensing method and device for random code external modulation. Background technique [0002] Distributed optical fiber sensor is a kind of sensing optical fiber sensor, which has the ability to simultaneously obtain the measured distribution information that changes with time and space in the sensing optical fiber area. It can be used to sense and detect the strain, temperature and other information of large buildings (such as dams and buildings). The detection optical fiber used in the detection is pre-laid in large buildings. This sensor is divided into forward transmission type and reflective type. The forward transmission type uses the effect of external physical quantities to cause energy coupling between the two transmission modes of the optical fiber. The characteristic is that the output end measures the coupled mode, and the frequency in its optical...

AI Technical Summary

Problems solved by technology

[0007] The present invention provides a distributed optical fiber sensing method and device with random code external modulation in order to solve the technical problem of the contradiction between the positioning accuracy and the temperature and strain measurement accuracy of the current distributed optical fiber sensor and the complicated structure

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