摘要：本文讨论了双层颗粒群产生的二次衍射，并给出了二次衍射复场分布的表达式，同时讨论了二次衍射与颗粒浓度之间的关系，找到了抑制二次衍射的最佳浓度。本文结论对于提高激光粒度仪的测量准确度具有重要意义。

关键词：激光;粒度分析;二次衍射;

Abstract：The re - diffraction resulted from the double layers partical group has been dis.Abstractcussed and the expression of complex field of re - diffraction is presented. The relationship be.tween the re - diffraction and the partical density has been discussed at the same time. The optimum density which can control the re - diffraction has been pinpointed. The result is important toadvance the measure accuracy of laser particat sizer.

Key words：lazer;particle size analysis; re - diffraction.