Effect of angular error on weighting coefficient in multiangle dynamic light scattering

Angular weight estimation is an important part of multi-angle dynamic light scattering technique. Its methods include autocorrelation function baseline method and light intensity average method. The effect of angular error on the measurement accuracy of particle size distribution, in the multi-angle dynamic light scattering, largely depends on the estimation of the angular weight coefficient. Based on the inversion of simulated and measured dynamic light scattering data, the effect of angle error on the inversion of particle size distribution by the weight estimation of autocorrelation function baseline method and light intensity average method was studied. The results show that there is no significant difference between the two methods without angle error. However, when the angle error exists, the influence of error on the inversion result of light intensity average method is greater than that of autocorrelation function baseline method, and the influence on large particles is greater than that on small particles. The reason for this result is that the weight coefficient obtained by light intensity average method based on Mie theory is the theoretical value, and there is a deviation between the theoretical value and the weight coefficient corresponding to the measured light intensity autocorrelation data. Moreover, with the increase of particle size, Mie scattering intensity exhibits a more drastic fluctuation with the scattering angle change, which causes the deviation to increase. Therefore, the angle weighted method based on Mie scattering intensity value was applied, and the precision of the multi-angle light scattering measurement device should be higher.