Particle Reconstruction with Optical Transfer Functions Applied to Tomo-PIV-Experiments

Abstract

A new approach to the weighting function, which describes particle imaging in the reconstruction process of tomographic PIV, is introduced. Instead of assuming a spatially homogeneous mapping function of a voxel to the images, a variable ‘optical transfer function’ (OTF) is applied. By this method, the effects of optical distortions, introduced during the recording process, can be reduced considerably. The effect of blurred particle imaging and astigmatisms on reconstruction and correlation quality is investigated via simulated data. Reconstructions using a spatially varying OTF, calibrated to the imaging conditions, show a significant improvement in reconstruction quality, correlation quality and accuracy of the particle peak position. First results on experimental data indicate a distinct reduction in ghost particle intensity compared to other approaches.