Three-dimensional particle size and position measurement by linear complex amplitude Wiener filtering.

Digital in-line holography (DIH) combined with a Wiener filter has been applied to measure particle size and position in the flow inside a capillary model, seeded with magnetic particles (3µm) and with solid opaque particles that simulated red and white cells. The proposed filtering process takes advantage of the linearity implicit in the numerical reconstruction of the object complex amplitude. A modified DIH set-up, with a tilted illumination beam, was used as it presents two main advantages: it solves the twin image issue associated to in-line holography and increases the out-of-plane resolution. Experiments show that the proposed method discriminates particles within a range from 3 to 30µm with a sensitivity of 0.5µm.