摘要
提出了一种结构简单的基于分布式反馈(DFB)光纤激光器的拍频解调系统,该解调系统的应变分辨率可以达到6.4×10-3με,动态范围可以达到400 MHz。提出的基于DFB光纤激光拍频解调技术的应变分辨率高于基于匹配光栅、线性滤波器和阵列波导光栅滤波器波长解调技术。动态范围大于基于可调谐激光器的相移光纤布拉格光栅强度解调技术和基于光纤干涉仪的光纤激光相位解调技术。整个系统的2个激光相互拍频得到拍频信号,通过基于虚拟仪器的信号采集处理系统进行处理。由高采样率的数据采集卡采集数据,通过基于LabVIEW的软件系统进行信号分析,得到拍频信号的频谱图。由频谱图得到拍频信号的带宽,再根据波长与频率的关系,DFB光纤激光器的灵敏度得到解调系统的应变分辨率。根据NI数据采集卡的采样率得到解调系统的动态范围。采用短时傅里叶变换法的时频分析方法提高应变分辨率。提出的DFB光纤激光拍频解调的声发射检测技术能够以较高的应变分辨率实现对由磨损或断裂等故障引起的高频声发射信号的检测。
A compact detection system based on distributed feedback(DFB)fiber laser using beat frequency interrogation was proposed,the detection system can reach a high strain resolution of 6.4×10-3με.And the dynamic range of the demodulation system can reach 400 MHz.The strain resolution of DFB beat frequency demodulation technique based on fiber laser is higher than that based on matched grating,linear filter and arrayed waveguide grating filter.The dynamic range is greater than the phase-shifted fiber Bragg grating intensity demodulation technique based on tunable laser and the fiber laser phase demodulation technique based on fiber interferometer.The two lasers of the whole system beat frequency each other to get the beat frequency signal.Then the signal acquisition and processing system based on virtual instrument developed by the Research Group is processed.Data are collected by a high sampling rate data acquisition card,and the spectrum of beat frequency signal is obtained by signal analysis based on LabVIEW software system.The bandwidth of beat frequency signal is obtained from the spectrum diagram,and the strain resolution of the demodulation system is obtained according to the relationship between wavelength and frequency,the sensitivity of DFB fiber laser.The dynamic range of the demodulation system is obtained according to the sampling rate of NI data acquisition card,and the strain resolution is improved by the time-frequency analysis method of short-time Fourier transform.The acoustic emission detection technique based on beat frequency demodulation of DFB fiber laser can detect high frequency acoustic emission signals caused by wear or fracture with high strain resolution.
作者
贾青
马怀祥
张文涛
黄稳柱
Jia Qing;Ma Huaixiang;Zhang Wentao;Huang Wenzhu(School of Mechanical Engineering,Shijiazhuang Tiedao University,Shijiazhuang 050043,China;Semiconductor Institute,Chinese Academy of Sciences,Beijing 100083,China)
出处
《石家庄铁道大学学报（自然科学版）》
2020年第3期86-91,96,共7页
Journal of Shijiazhuang Tiedao University(Natural Science Edition)
基金
石家庄铁道大学研究生创新资助项目(YC2018047)。
关键词
分布式反馈光纤激光器
解调
拍频
LABVIEW
时频分析
声发射
distributed feedback fiber laser
demodulation
beat frequency
LabVIEW
time-frequency analysis
acoustic emission
作者简介
贾青(1992-),男,硕士研究生,研究方向为于光纤声发射传感。E-mail:1104605338@qq.com。
