Ray-tracing 3D PIV/PTV for sparse particle distribution with a light field camera

We will discuss a rapid 3D reconstruction of sparse particles distribution especially suitable for micro-scale interrogation volumes. Lighting difficulties and space constraints limit micro-scale particle image velocimetry (PIV) and particle tracking velocimetry (PTV) using a standard approach. Also, multiplicative algebraic reconstruction (MART) and simultaneous algebraic reconstruction technique (SART) used for light field reconstruction require large memory and substantial computational power to process the data. The use of microlens arrays (MLA) into the optical train of a microscope, 5D light array, which describes pixel position and direction of light, can provide a robust calibration method. Ray tracing and cloud point classification algorithm is used to obtain the spatial position of particles based on device parameters quickly in the order of a couple of seconds. We will discuss uncertainty using simulated setups with known particle positions and comparison with refocused positions. We discuss the 3D PIV approach to characterize the flow in a simple micro channel.