defocussing, i.e. the expansion of the particle image can be used when using only one camera [1]. Figure 1 shows the basic connection between depth position of a particle and the resulting image on an [...] Hough-Transformation under the assumption of circles [2]. fig. 1 - scheme for the extraction of depth information of particles via defocusing [1] Willert, C.E. and M. Gharib, Three-dimensional particle imaging
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