连续波腔衰荡光谱系统的电路设计与应用

Electrocircuit design and application in continuous-wave cavity ring-down spectroscopy system

为实现连续波腔衰荡光谱系统的工程化,设计了一套集信号调理、高速采样及数据处理为一体的高集成度数字信号处理(DSP)系统。该系统被用于取代常规连续波腔衰荡光谱系统中由高速数据采集卡及计算机组成的腔衰荡信号测试系统,完成对腔衰荡信号的获取与拟合。该系统最高能实现16bits/80MHz的信号采样,并能准确地由腔衰荡信号反演出腔衰荡时间。实验结果表明:结合现有的光反馈式连续波腔衰荡光谱系统,该系统能实现等噪声测量灵敏度为1.0×10-8 cm-1的吸收光谱测量,其重复测量精度可达3‰。

For the convenient application of continuous-wave cavity ring-down spectroscopy（CW-CRDS）,a compact measure system based on the DSP technique is presented.The DSP system is capable of signal adjustment,high-speed signal acquisition,and data processing.It is used to replace a test system composed of high-speed A/D card and computer in the traditional CW-CRDS measure system,to obtain and fit the ring-down signal.The fastest acquisition speed of the DSP system can reach 80 MHz with the A/D resolution of 16 bits,thus it can obtain the ring-down signal and determine the ring-down time accurately.Experiments show that the DSP system can achieve the noise-equivalent（RMS） absorption coefficient of about 1.0×10-8 cm-1 in an optical feedback CW-CRDS system,and its repeatability at a single laser wavelength is about 3‰.