基于FFT的动态散射光谱密度测量技术研究

为了研究动态光散射纳米颗粒测量技术，提出了基于FFT的动态散射光AR模型功率谱密度测量法。首先采用FFT建立信号的AR功率谱密度模型，然后通过计算信号自相关矩阵的秩得到AR模型的阶数P，由于任何信号的自相关与其频域的功率谱密度是一个傅里叶变换对，因此，信号功率谱密度的衰减宽度等价于其自相关函数的衰减宽度，这样通过计算动态光散射信号的功率谱密度衰减宽度，进而得到待测颗粒的粒径，最后将此方法的实验结果与传统的光子相关光谱法实验所测得的数据进行了比较。结果表明：该技术具有误差小、重复性好的优势，有着很大的实用价值。

The research of dynamic light scattering system with power spectral density based on FFT

To do the research of the particle sizing based on the dynamic light scattering,the author proposed the power spectral density(PSD) with AR model,which is based on the FFT.The author created AR model for PSD by using FFT,and then achieved the level p of the AR model by calculating the rank of the signal's autocorelation matrix.The autocorelation of the singal can be achieved by using FFT of the signal's PSD.Therefore,the decaying width of the signal's PSD is equal with that of the signal's autocorelation.By calculating the decaying width of the signal's PSD,the particle' diameter could be achieved.Through the comparative analysis of the particle diameter gained by two different methodology of PSD and the photon correlation spectroscopy,the author considered that the methodology of PSD has advantages of smaller error and better repeatability.So,this methodology has better practical value.