Plenoptic self-aligned focusing schlieren

Abstract A plenoptic camera was coupled into a self-aligned focusing schlieren (SAFS) system, allowing for the instantaneous capture of focused schlieren images at multiple planes from a single snapshot. Each focused schlieren image can be refocused to an arbitrary depth, within limits discussed herein, revealing density gradients at different spatial locations in the flow. A description of the plenoptic SAFS system is presented, along with a characterization of the experimental system. This characterization details the two depths-of-field associated with a plenoptic camera; the so-called reduced aperture depth-of-field, which gives the refocusing range, and the full aperture depth-of-field, which determines the depth-of-field of the final refocused image. Further, the spatial resolution of the plenoptic SAFS system was determined via a modulation transfer function analysis using a slant-edge target. Finally, results of an experiment consisting of two helium jets in both side-by-side and inline, vertically-opposed configurations are presented, as well as results from a wind tunnel experiment.