弹光调制干涉信号放大滤波电路设计

Amplifying filter circuit design for interference signal of photoelastic modulated interferometer

从弹光调制干涉具中出来的干涉光经过探测器接收所输出的电信号频率很高且幅度只有几十毫伏左右,极易受到噪声干扰。有效地将其检测提取并放大至高速AD采集信号范围600 m V^4 V对弹光调制-傅里叶变换光谱仪的光谱反演至关重要。因此,需要设计一种高频、高增益、低噪声的两级放大电路。该电路主要由直流稳压电源电路、小信号放大电路和截止频率为50 MHz的低通无源滤波电路组成。实验结果表明,该放大滤波电路可以将弹光干涉信号平稳放大至150倍左右,能够为后续的采集存储提供良好的信号源。

The interference light come out from the photolastic modulation interference which is received by the detector and then exported signal is a high frequency , it is about tens of millivolts and susceptible to be interfered by noise. It is essential for the spectral inversion of Fourier transform spectrometer if we can detect and extract it and amplify to the range of high-speed AD ac- quisition signal which is 600 mV to 4 V bomb on the subsequent optical modulator effectively. Therefore, we need to design a two- stage amplification circuit of high frequency, high-gain and low-noise. It is mainly composed of DC power supply circuit, small signal amplification circuit and a low-pass passive filter circuit which has a cutoff frequency of 50 MHz. The experimental results show that the amplification filter circuit can amplify the input photoelastic signal to 150 times or so steadily, which can provide good signal for subsequential collection and storage.