Laser nonlinear tuning effect compensation system and compensation method for optical frequency domain reflectometer

An optical frequency domain reflectometer and nonlinear tuning technology, which is applied in the direction of transmitting sensing components, instruments, and converting sensor output with optical devices, so as to achieve the effect of increasing the maximum measurable length and increasing the measurement distance

Active Publication Date: 2020-07-10
NANJING UNIV
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Problems solved by technology

This method is simple and data processing is convenient, but limited by the Nyquist sampling theorem, the longest measurement length is only 1 / 4 of the delay fiber of the auxiliary interferometer

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  • Laser nonlinear tuning effect compensation system and compensation method for optical frequency domain reflectometer
  • Laser nonlinear tuning effect compensation system and compensation method for optical frequency domain reflectometer
  • Laser nonlinear tuning effect compensation system and compensation method for optical frequency domain reflectometer

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Embodiment Construction

[0029] The specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing:

[0030] In OFDR, the light source used is a tunable laser. The frequency-sweeping light emitted by the laser passes through the reference path and the measurement path, and beat frequency occurs. When the laser sweeps linearly, there is a one-to-one correspondence between the beat frequency and the position of the optical fiber to be tested. relationship: f b =2γnz / c. The collected signal is converted from the time domain to the frequency domain by Fourier transform, and the position information of the reflection point can be obtained according to this relationship. However, lasers generally have a nonlinear frequency sweep. At this time, the sweep rate is a function of time, and the relationship between the beat frequency and the position of the fiber to be tested becomes: f b =2γ(t)nz / c, one position corresponds to multiple beat frequencies, resul...

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Abstract

The invention discloses a laser nonlinear tuning effect compensation system for an optical frequency domain reflectometer (OFDR). The method comprises: firstly, connecting an acousto-optic frequency shifter (AOM) into an interference arm of an OFDR auxiliary interferometer to shift the frequency of light waves, and increasing the beat frequency signal frequency of the auxiliary interferometer; converting the beat frequency signal into an alternating current signal through a photoelectric detector, and correcting a measurement signal of the main interferometer by taking a zero crossing point ofthe signal as a reference point. The correction process comprises five steps of solving zero-crossing points, calculating a frequency interval between every two zero-crossing points, eliminating additional frequency introduced by AOM, solving a correction coefficient and correcting abscissa. The correction signal obtained in the process is used for OFDR detection, the influence of the nonlinear tuning effect of a light source can be effectively overcome, and the spatial resolution of the OFDR is improved.

Description

technical field [0001] The invention belongs to the field of distributed optical fiber sensing, and in particular relates to a laser nonlinear tuning effect compensation system and compensation method for an optical frequency domain reflectometer. Background technique [0002] Optical Frequency Domain Reflectometer (OFDR) technology was first proposed by Eickhoff et al. in 1981. In the past few years, OFDR has played an important role in the field of distributed optical fiber sensing due to its advantages of high spatial resolution and high sensitivity. Its main applications include temperature sensing, strain sensing, and shape sensing. [0003] In the basic OFDR, the frequency-sweeping light emitted by the tunable laser is divided into two paths, one path is used as the reference light, and the other path enters the optical fiber to be tested. The reflected or scattered light and the reference light have a beat frequency. To detect the characteristics of the optical fiber...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D5/353G01D18/00
CPCG01D5/35393G01D5/35306G01D18/00
Inventor 王峰邢婧婧章颖张旭苹张益昕
Owner NANJING UNIV
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