Assessment of radial image distortion and spherical aberration on three-dimensional synthetic aperture particle image velocimetry measurements

Abstract

This thesis presents a numerical study of the effects of radial image distortion and spherical aberration on reconstruction quality of synthetic aperture particle image velocimetry (SAPIV) measurements. A simulated SAPIV system is used to image a synthetic particle volume. An idealized pinhole camera model is used for image formation with distortion and spherical aberration being added with a polynomial model and a Fourier waveform model, respectively. Images from a simulated 5 x 5 camera array are taken, distorted and/or aberrated, realigned and averaged to form synthetic aperture images at a set of depths within the particle volume. These images are thresholded to recover three-dimensional particle locations and a reconstructed three-dimensional intensity field is formed. This reconstructed field is then evaluated according to intensity data and a signal-to-noise ratio (SNR). Results show that even small amounts of image distortion and spherical aberration can lead to degradation of SNR and information loss.