中文摘要：

窄光束照射流动颗粒系时，透过率会产生起伏。起伏的透过率信号可用来测量颗粒平均粒径和浓度。由于在测量原理和结构上非常简单，这种方法可用来实现在线、实时测量。Gregory提出的数据处理模型要求光束直径较小而且远大于颗粒直径，本文提出一种新的模型，可在光束直径接近甚至小于颗粒直径情况下对透过率起伏信号进行处理，模拟分析和实验测试表明，该方法可得到较满意的测量结果。

英文摘要：

The transmission signal of a narrow beam irradiated on a flow particle system may fluctuate. The fluctuating transmission can be used to measure the particle size and particle concentration. Due to the simplicity in principle and in optical arrangement, this method may be applied to the real time, online measurement. In the method proposed by Gregory, the beam diameter is necessary to be small but it should be much larger than the particle size. In this work, a new model of data processing is presented, in which the beam diameter may be close to or even much smaller than the particle size. The numerical simulation and the experiments show that this model can attain more reasonable results.