A Microparticle Image Velocimetry Based on Light Field Imaging

摘要

Accurate 3D flow characterization in a microchannel is becoming increasingly important for the design and development of microfluidic chips. In recent years, a light field camera that can simultaneously record the direction and position information of rays in a single photographic exposure has been developed and employed in the field of computer graphics. In this paper, a microparticle image velocimetry based on light field imaging (light field mu PIV) is proposed to reconstruct the 3D velocity field of a microscale flow. Both simulations and experiments are performed to verify the proposed method. The light field image of tracer particles and the point spread function (PSF) of a light field microscopic imaging system are numerically calculated based on the Abbe imaging principle. The 3D positions of the tracer particles in a flow field are then reconstructed by the Lucy-Richardson 3D deconvolution algorithm. Furthermore, a light field mu PIV system based on an assembled cage light field camera with a microscope is developed, and calibrations are performed to obtain the geometric parameters of the mu PIV system accurately. The simulation and experimental results demonstrate the feasibility of the proposed light field mu PIV. Compared with the synthetic refocusing reconstruction method, the Lucy-Richardson 3D deconvolution algorithm greatly improves the lateral and the axial resolutions of the flow field.