A microscopic spatial filtering velocimeter for measurements of lymph flow in microcirculation

In order to analyze the velocity change of lymphocyte flow in microcirculation in vivo, a spatial filtering velocimeter was applied to velocity measurements in the microscopy region. The spatial filter was constructed with an optical fiber array and the moving lymphocyte image was formed on it through a microscope. The frequency of the output signal was related to the lymphocyte velocity. The lymphocyte flow velocity was periodically changed and backward flow was often observed. An image of the lymph vessel was also recorded, and the relationship between the velocity change of lymphocyte flow and the contraction of the lymph vessel was considered. The optical fiber array spatial filtering velocimeter was applied to measurements of the lymph flow velocity in rat mesentery. The periodic time of the velocity change of the lymph flow and of the diameter change of the lymph vessel were about 2~3 seconds and it was much longer than that of the cardiac action