Optically sliced micro-PIV using confocal laser scanning microscopy (CLSM)

Optically sliced microscopic-particle image velocimetry (micro-PIV) is developed using confocal laser scanning microscopy (CLSM). The developed PIV system shows a unique optical slicing capability allowing true depth-wise resolved micro-PIV vector field mapping. A comparative study between CLSM micro-PIV and conventional epi-fluorescence micro-PIV is presented. Both techniques have been applied to the creeping Poiseuille flows in two different microtubes of 99-mum (Re=0.00275) and 516-mum ID diameters (Re=0.021), which are respectively imaged by a 40x-0.75NA objective with an estimated 2.8-mum optical slice thickness, and by a 10x-0.30NA objective with a 26.7-mum slicing. Compared to conventional micro-PIV, CLSM micro-PIV consistently shows significantly improved particle image contrasts, definitions, and measured flow vector fields agreeing more accurately with predictions based on the Poiseuille flow fields. The data improvement due to the optical slicing of CLSM micro-PIV is more pronounced with higher magnification imaging with higher NA objectives for a smaller microtube.