A video image correlation technique for the measurement of electrophoretic mobility

The electrophoretic movement of blood cells has been examined with a video image correlator using the signal from a 625 line monochrome television camera attached to the optical arrangement. The diffraction pattern of a cell produces a characteristic signal which can be detected and registered in any television scan line to form the data of the first image frame. Under the influence of an electric field, cells moved across the television field of view and after a short interval appeared on different scan lines. The detection and registering process was repeated, and a cross-correlation function between the first and second image frame was computed. This function was stored in an output buffer which was continuously updated as fresh functions were integrated with the existing contents. The mean electrophoretic mobility of a suspension of particles can be calculated from the peak position of the integrated correlation function. Using a triangle deconvolution procedure, the relative contributions of subpopulations of lymphocytes prepared from peripheral blood samples were examined.