微弱光纤声发射信号检测电路建模与仿真

采用双波长稳定技术可克服光纤声发射传感器正交工作点偏移产生的信号衰减与失真,但会造成输出光微弱而难以检测。针对该问题,给出一种光纤声发射信号检测电路设计方案,建立了光电管、前置运放、电流转换的子模型及系统模型,分析了系统噪声特性与稳定性,并采用通用电路模拟软件PSPICE进行仿真验证,仿真实验结果表明,采用该设计方案能有效展宽频带和提高信噪比,可用于频带宽度为318 kHz与幅值低达1 nA的光电流检测。

Modeling and Imitation of Weak Fiber Optic Acoustic Emission Signal Detection Circuit

The signal attenuation and distortion induced by fiber optic acoustic emission sensor quadrature point shift can be eliminated by using two wavelength stability technique,but the output light signal is too weak to detect.Aiming at this problem,a design scheme detecting weak fiber optic acoustic emission signal has been proposed,and the sub-model of photodiode,preamplifier and current conversion and system model are constructed.System stability and noise characters are analyzed, and the analysis result is validated by PSPICE simulation software.The simulation result indicates that the system band is widened and signal-to-noise ratio is improved by adopting this design scheme,and it can be applied to detect photocurrent as low as 1 nA with a 318 kHz bandwidth.