近红外光谱仪中的数字锁相技术研究

Study on digital lock-in amplifier in NIR spectrometer

本文分析了光栅扫描型近红外光谱仪中光谱信号频率波动引起的测量误差问题,提出了一种同步整周期采样的正交DPSD方法,讨论了实现这种方法的几点注意事项。最后,给出了这种方法与原模拟锁相放大器的信噪比对比测试实验结果。理论分析和实验结果表明:此方法与模拟锁相方法相比输出信噪比提高了一倍多,可以应用于近红外光谱仪的微弱信号检测,能够精确地从噪声中提取出光谱信号,达到了良好效果。

The paper analyses the measuring errors caused by frequency fluctuation of spectrum signal, puts forward a new integer-period sampling DPSD method, and discusses several noticeable points. At last the comparative signal-to noise test results between this method and ALIA are presented. Theoretical analysis and test results show that signal to-noise ratio was improved by more than one time compared to ALIA, this method can be used in NIR spectrometer＇s weak signal detection, and the spectrum signal can be acquired from the strong noise accurately.