Backward interferometric speckle imaging for evaluating size and morphology of irregular coal particles

Abstract The size and morphology of irregular particles are essential parameters for a variety of industrial processes. The backward interferometric speckle imaging technique can be applied to measure the relevant parameters of opaque irregular particles. To verify the accuracy of the backward interferometric speckle imaging technique, an elaborately designed experimental system was used to combine a backward interferometric speckle imaging system with a digital inline holography (DIH) system to characterise the same pulverised coal particles for quantitative comparison. The results of the backward interferometric speckle imaging were in good agreement with those of DIH in terms of particle size and morphology. In the backward interferometric speckle imaging system, the laser illumination and recording system are configured on the same side, and therefore only one window is required during measurement. This facilitates its instrument integration and provides significant potential for industrial applications involving powder processing.