FRINGE MODE TRANSMITTANCE LASER DOPPLER MICROSCOPE ANEMOMETER - ITS ADAPTATION FOR MEASUREMENT IN THE MICROCIRCULATION

Blood flow analysis in the microcirculation requires accurate measurement of velocity, volume flow and shear-rate versus shear-stress relationships. The resolutions of most anemometers is too limited to obtain useful measurements, especially near the blood vessel wall and at branches and bifurcations. To make such measurements possible with a noninvasive, high-resolution, accurate technique the authors have developed a fringe mode, transmittance laser Doppler microscope anemometer (LDMA). This system has an intrinsically high spatial resolution (10×12μm), and does not require a high concentration (106/cm3) of scatterers or red blood cells. Preliminary measurements of water flow in a rectangular channel were conducted to ascertain the reliability and accuracy of velocity measurements using the LDMA. Velocity profiles were then measured by the LDMA system in arterioles 38-135μm in diameter, in the transparent, everted check pouch of the anaesthetized hamster. The extremely high resolution of the optical system, and the ultrafine traversing mechanism of the microscope stage, made velocity readings larger than 0.02 mm/s with accuracy and reproducibility better than 1% possible near the wall to within 7-10μm.