提高动态光散射测量系统信噪比的一种方法

Method to enhance signal to noise ratio of DLS measurement system

通过对光电倍增管计数统计特性的分析,提出了由于光电倍增管的光电子发射是一个随机过程,在计算光子自相关函数时,就会引入一个Poisson噪声。因此,根据Wiener-Khintchine定理,将时域自相关函数转换为频域的功率谱密度,采用数字滤波的方法滤除Poisson噪声及无效直流信号,可明显提高系统的信噪比,并通过实验证实了该方法的合理性。

Through analyzing the counting statistics properties of photon multiplier tube （PMT）, it is proposed that Poisson noise is added on the photon auto-correlation function （ACF） since photoelectron emission of PMT is a random process. Therefore, according to Wiene-r-Khintchine theorem, the ACF in time domain is transformed into pow- er spectrum in frequency domain and the digital filtering method is applied to filter out the Poisson noise and direct current （DC） signal, which enhances the signal to noise ratio significantly. At last, the rationality of the method is proved by experiment.