Three-dimensional particle tracking by pixel difference method of optical path length based on digital holographic microscopy

Abstract

Particle tracking with nanometer resolution is of growing importance in microrheology, microfluidics, and life science. Pixel difference method of optical path length (OPL) is a proposed novel digital holographic microscopy (DHM) method to achieve 3D particle tracking utilizing configuration of an off-axis digital holographic microscope. Pixel difference methodology focuses on variation of the OPL of two fixed pixel points in the recording plane. In this method, the second derivative of OPL difference is a tracking tag. Instead of calculating two dimensional images in classical DHM, pixel difference method of OPL only concerns trend of one-dimensional data series. In this sense, the tracking efficiency, which is important in dynamic investigation, is improved. Pixel difference of OPL, with nanometer-scale resolution, is presented as applicable in particle tracking by tracking the beads fixed on the piezoelectric stage with nanometer precision.