Simultaneous 3D location and size measurement of spherical bubbles using cylindrical interferometric out-of-focus imaging

•We realize a cylindrical out-of-focus imaging of spherical bubbles.•The method allows the simultaneous 3D location and size measurement of bubbles.•The theoretical design is based on the Generalized Huygens-Fresnel integrals.•Characterization of bubbles is done using fast image processing.

A cylindrical interferometric out-of-focus imaging set-up is presented for the characterization of spherical bubbles. The design of the set-up is realized using transfer matrix based models. The simultaneous three-dimensional (3D) location and size measurement of bubbles is demonstrated using fast Fourier transform algorithms. Experimental results are in very good agreement with theoretical predictions.