[Research on pattern search method for inversion of particle size distribution in spectral extinction technique]

Development of rapid and efficient inversion methods for retrieval of particle size distribution (PSD) is an important subject of research effort. The main intention of the present paper is to develop pattern search method combined with Tikhonov smoothing functional for the determination of un-parameterized shape-independent PSD in spectral extinction technique. To ensure a good rapidity and accuracy of the whole search process, a competitive strategy was also designed. The inversion results for standard spherical polystyrene samples using the proposed method show that the relative error for volume mean diameter is 3.14% which does not exceed the range of +/- 8% specified by the National Bureau of Standard Reference Material of China. Moreover, the breadth of the inversed PSD is satisfied and there are not obvious artifact peaks. When compared with Phillips-Twomey method and genetic algorithm, the modified pattern search method has advantages concerning the inversion precision and inversion time, which makes the proposed method more suitable for quick and accurate measurement of particle sizing.