A calibration procedure for millimeter-scale stereomicroscopic particle image velocimetry

A stereomicroscopic particle image velocimetry (S mu PIV) system has been developed for millimeter scale flows. The S mu PIV system is based on an off-the-shelf stereomicroscope, with magnification between 0.69x and 30x, and a field of view between 7.5 x 6 mm and 250 x 200 mu m. Custom calibration targets were devised using printed circuit board technology, and applied at a magnification factor of 1.74, with a field of view of 4.75 x 3.8 mm. Measurement errors were assessed by moving a test block with fixed particles. Total system uncertainty in test block displacement transverse to the optical axis was 0.5% of the field of view, and 3% of the depth of field for motion along the optical axis. Approximately 20% of this uncertainty was due to the calibration target quality and test block procedures.