宽动态范围微弱光电信号检测系统

Wide Dynamic Range Weak Photoelectric Signal Detection System

昼夜工作的探测器在一天中处于不同照度环境下的信号探测,为了精确测量出工作在宽动态范围照度下的光电探测器的输出信号,利用FPGA工具和相关检测原理设计了一套宽动态范围高精度信号测量采集系统;该系统由接收光学系统模块,跨阻放大电路模块,锁相放大电路模块以及A/D采集模块组成,接受光学系统实现了屏蔽杂散光功能,对水平与垂直方向上的光强进行了误差校正;跨阻放大电路和锁相放大电路实现了微弱信号的放大和噪声的抑制,A/D采集模块将数据实时采集显示;在暗室环境下,以中心波长为650 nm稳功率激光器为光源,使用滨松S2386-5K光敏二极管为光电探测器进行试验,实验过程中通过改变信号调制频率和激光器功率大小,最终选择调制信号频率为1000 Hz最为适宜;实验结果表明,光电检测系统在照度范围为0.01~100 lx均可以完成准确测量,拓宽了测量的动态范围,实际测量值与理论值误差在精度允许范围之内,该研究对于其它波长的光源或其它微弱信号检测系统的设计与分析具有借鉴意义.

Under the different illumination environments,the photodetector working day and night can accurately measure the output signal under a wide dynamic range of illumination,a set of wide dynamic range of high-precision signal measurement and acquisition system is designed by using the FPGA tools and related detection principles;The system is composed of the receiving optical system module,transimpedance amplifier circuit module,lock-in amplifier circuit module and A/D acquisition module.The receiving optical system realizes the function of shielding stray light,and the error correction of the light intensity is carried out in the horizontal and vertical directions;The transimpedance amplifier circuit and the lock-in amplifier circuit are used to realize the amplification of weak signals and the suppression of noise,and the A/D acquisition module collects and displays the data in real time;In the dark room environment,the center wavelength of 650 nm is used to stabilize the power laser as the light source,and the Hamamatsu S2386-5K photodiode is used as the photodetector for the experiment.During the experiment,the signal modulation frequency and the laser power are changed,and the modulation signal frequency of 1000 Hz is finally selected.The experimental results show that the measurement of photoelectric detection system can be accurately completed in the illuminance range of 0.01 lx to 100 lx,which broadens the dynamic range of measurement,and the error between the actual measured value and the theoretical value is controlled in the allowable accurate range.This research provides the reference for the design and analysis of light sources with other wavelengths or other weak signal detection systems.