Calibration scheme for three-dimensional particle tracking with a prismatic light

A scheme is described for determining the three-dimensional translational motions of rigid particles in a liquid medium using only one color video camera. It is based on the principle that when rigid particles pass through a light sheet whose spectrum varies with its thickness, they reflect rays of varying color. If the particles are observed using a camera whose axis is set normal to the light sheet, their motions can be determined from their loci and colors, as observed on a video monitor. The rays reflected from the particles are matched to their loci through color analysis. A calibration curve obtained using this scheme was used to estimate the loci of particles with a diameter of about 100 mum; the maximum error was 0.51 mm, and the standard deviation of the calibration curve was 0.21 mm when the hue angle of the reflected rays was between 0.9degrees and 110degrees (this hue angle range corresponds to a particle displacement of about 3.8 mm in the spectrum-change direction). (C) 2004 American Institute of Physics.