Inversion of particle size from light-scattering data by differentiating the distribution width and convergence threshold

An improved conjugate gradient algorithm (ICGA) is presented to inverted particle size distribution (PSD) with ensemble light scattering methods. The narrow unimodal, broad unimodal, or the multipeak modal PSD can be inverted from diffraction data with ICGA. In the algorithm, a convergence threshold should be changed according to the particle size distribution width (PSDW). However, we cannot always know the PSDW beforehand, thus we propose to calculate the PSDW by the light-scattering data. Afterward, we can select the convergence threshold. We experimented on some samples and their mixture. The results show the proposed method can be applied to inverted PSD with different distribution models. The resulting errors on the above samples are within 4.55%. The mixture of some particulate certified reference materials can be discerned distinctly, thus the resulting resolutions are acceptable. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3578400]