Quantitative 2D microscopic flow velocity determination using a novel confocal laser Do

摘要

Abstract: We describe a novel three-beam confocal laser Doppler microscope (CLDM) which allows 2D microscopic velocity flow measurements and utilizes the benefits of both the Doppler mode of contrast formation and the high lateral and axial resolution imaging capability of confocal microscopy. This is accomplished by a microscope objective focusing three laser beams to produce a 'probe volume' within a specimen, rather than the traditional two input beams. The specimen is mounted on a scanning stage, which enables the final image to be constructed point by point. The two dimensional velocity information of the particles within this probe volume are 'encoded' into the beat frequencies of the back scattered light. By using digital filtering to deinterlace the individual signals and computer reconstruction techniques, 'velocity images' will be formed. These velocity images, produced solely by Doppler scattering of light from moving particles, displays the flow distribution within some defined area. Our goal is to eventually produce a full three dimensional velocity volume of a biological cell, which would truly be a significant innovation in microscopy. We demonstrate an experimental optical device capable of forming the required three independent fringe fields inside the probe volume, examine this probe volume from a theoretical basis and perform an analysis of the scattered light frequencies. Preliminary experimental results are presented. !2