基于FPGA高速信号采集的多角度动态光散射法纳米粒径测量

Nano-particle Size Measurement by Multi-angle Dynamic Light Scattering Based on FPGA High-speed Signal Acquisition

根据动态光散射装置测量纳米粒径原理,开发了一套基于现场可编程门阵列(FPGA)的纳米粒径测量系统。该系统通过光电倍增管(PMT)输出光子脉冲信号,利用FPGA实现高速脉冲采集及自相关运算,采用双脉冲计数器实现高精度可控的连续计数,并实现DDR3异步存储以及USB通信交互等接口功能。自研板卡既可实现自相关函数实时采集运算,又可无丢失地保存海量原始数据信号。采用该系统对200 nm聚苯乙烯颗粒进行了测量,分析了不同采样时间及延迟时间等参数对粒径测量结果的影响。实验结果表明:自研FPGA采集板卡测量重复性为1.2%,具有很好的稳定性和重复性。

According to the principle of measuring nano-particle size by dynamic light scattering device,an apparatus of nano-particle size measurement system based on field programmable gate array(FPGA)is developed.Scattering light signalsare transferring in to level signal through photomultiplier tubes(PMT),and an FPGA is developed to realize high-speed pulse collection and autocorrelation function calculation.Double pulse counting is used to achieve high-precision and controllable continuous signal counting.DDR3 is used to achieve asynchronous storage,and then connected with PC ends by using USB communication interaction functions.The home-designed FPGA card can both calculate autocorrelation function inside as well as achieve mass original data storage.200 nm polystyrene particles is measured and the effects of different sampling time and delay time parameters on the particle size measurement results are analyzed.Experimental results show that the self-developed FPGA acquisition board measurement repeatability is 1.2%,can achieve accurate signal acquisition and has excellent stability and repeatability.