基于锁定放大的微弱激光回波信号探测系统

Weak laser echo signal system detection based on lock-in amplifier technology

微弱信号检测的核心问题是对噪声的处理,为了探测深埋于噪声中的微弱激光回波信号,设计并搭建了一套锁定放大信号检测系统。PIN光电二极管探测到的微弱激光回波信号由前置放大电路和二级放大电路转换为电压信号并放大,再经带通滤波器滤除带外噪声,最后通过相敏检波电路,转换为与回波光强成正比的直流电压信号输出。测试结果表明,系统可以有效抑制噪声,被测信号的信噪比改善超过10.6dB。

The core problem of weak signal detection is noise processing.In order to detect the weak laser echo signal deeply buried in the noise,a weak signal detection system based on lock-in amplifier is proposed.Weak laser echo signal detected by PIN photodiode is converted into a voltage signal and amplified by the preamplifier circuit and the second stage amplifier.Then through the band-pass filter the out of band noise is removed.Finally the signal is converted the DC voltage signal proportional to the echo intensity through the phase sensitive detection circuit.Test results show that the system can effectively restrain the noise and the signal to noise ratio of the measured can be improved more than 10.6 dB.