Self-correcting fully-distributed optical fiber Raman scattering sensor

Abstract

The invention discloses a self-correcting fully-distributed optical fiber Raman scattering sensor. In the invention, a duplex fiber cable is utilized as a sensing optical fiber, pump light is divided into a forward beam and a backward beam during the transmission process by welding the tail ends of the duplex fiber cable together so as to obtain two anti-Stokes Raman scattering light beams, and the intensity of the anti-Stokes Raman scattering light beams is measured so as to realize temperature measurement; and the intensity values of the two anti-Stokes Raman scattering light beams can be multiplied so as to achieve the purpose of self-correction of curvature, loss, strain and the like. The sensor disclosed by the invention comprises an optical fiber pulse laser, an optical fiber wavelength division multiplexer (WDM), the duplex fiber cable, a photoelectric receiving module, a digital signal processor (DSP) and a computer. The invention has the advantages that self-correction and temperature measurement can be carried out at the same time only by measuring the intensity of the anti-Stokes Raman scattering spectrums; and the system has a simple structure, and avoids the defects that the traditional measuring system has transmission loss and errors caused by different center wavelength and needs a plurality of photoelectric receivers.

Description

technical field [0001] The invention belongs to the field of optical fiber sensing and temperature measurement, and relates to a self-correcting fully distributed optical fiber Raman scattering sensor. The sensor is suitable for occasions that require simple structure, low cost, and wide application, such as real-time continuous monitoring of production processes, civil engineering, and disaster monitoring. technical background [0002] In recent years, optical fiber sensors, especially distributed optical fiber Raman scattering sensors, have received extensive attention and research due to their advantages of simple operation, safety, and applicability to harsh environments. This type of sensor utilizes the intrinsic characteristics of optical fiber, optical fiber Rayleigh, Raman and Brillouin scattering effects, and uses optical time domain (OTDR) technology to monitor temperature. The optical fiber in the fully distributed optical fiber sensor network is both the transmi...

AI Technical Summary

Problems solved by technology

Traditional distributed optical fiber Raman scattering sensors mainly use the ratio of temperature-sensitive anti-Stokes Raman scattering light intensity to Rayleigh scattering light intensity or Stokes scattering light intensity to obtain temperature information. The measurement error is caused by the fluctuation of the light source, but as the measurement distance increases, in order to obtain higher measurement accuracy, the transmission caused by the different central wavelengths of anti-Stokes scattering, Stokes scattering and Rayleigh scattering Loss needs to be corrected

Therefore, the research proposes a method of using dual light sources. This method uses two main lasers and auxiliary lasers with different central wavelengths. The anti-Stokes Raman scattering wavelength of the main laser and the central wavelength of the auxiliary laser are the same to eliminate the differences in wavelength. However, this structure needs to add a laser, an optical switch, and two photodetection modules, which increases the system structure and increases the cost of use.

In 2010, South Korea Dusun Hwang et al. proposed a method of adding a reflector at the end of the sensing fiber, which can realize temperature monitoring and self-correction at the same time, (OPTICS EXPRESS, 2010, Vol.18, No.10: 9747-9754) but The addition of mirrors attenuates the energy of the pump light and the anti-Stokes light signal, reducing the system's performance-to-noise ratio

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