Microscopic laser Doppler velocimeter measuring blood velocity in single microvessel

A microscopic laser Doppler velocimeter to measure blood velocity in single microvessels was developed. In order to measure the blood velocity in microvessels correctly, the influence of stray scattered light from vessel wall should be removed. Because it provokes low-frequency spurious components. The spectra of the spurious components overlap with that of Doppler signal and induces considerable error in the result of the blood velocity when the velocity is reduced. The optical configuration of the velocimeter was optimized to eliminate the influence of the stray scattered light. The blood velocity in microvessels in rat mesentery was measured with the microscopic laser Doppler velocimeter and the periodical fluctuation of the velocity was analyzed. Pulsatile velocity fluctuation could be observed even in capillary.