Study On Nanoscale Particle Sizing Instrument Based On Backscattering Optic Fiber Probe

Because the traditional dynamic light scattering method can't measure the nano particle size in high concentration solution. Through the analysis of the time domain correlation theory of the dynamic light scattering, we developed a kind of integrated optical fiber probe based on the backward dynamic light scattering method. This kind of probe overcomes the defect of the traditional dynamic light scattering method. In this paper, the main research contents are as follows:1, When we use the traditional dynamic light scattering method to measure the size of nano particles solution, the effects of multiple scattering began to show its effects in relatively low concentration. So the key to develop a kind of dynamic light scattering technique that can be used for detecting high concentration of nano particles is to weak the influence of multiple scattering.2, This paper uses the method of reduced scattering path to weaken the influence of multiple scattering, and studies on optical fiber probe spatial coherence. By analyzing the factors that influence the spatial coherence(spatial coherence angle, coherence area and scattering volume) to find the method that can improve the coherence of the optical fiber probe.3, According to the criterion of satisfy the spatial coherence and based on the analysis of the structure parameters of the fiber probe, the optimum design method of the structure parameters in backscattering probe is given.The optical fiber integrated probe can not only accurately measure the size of nano particles in low concentration solution, but also in high concentration solution. The experiment results show that, the relative error and repeatability are all smaller than 5%.