Blood Velocity Measurement by Fiber Optic Laser Doppler Anemometry

Laser Doppler anemometry has been used to measure blood velocities by using a fine fiber optic probe both to deliver laser light into the blood and to receive reflected light from red blood cells at the tip of the probe. In vitro, with the probe aligned in the direction of flow, nonlinear calibration is possible to velocities of 15 cm/s in a 3 mm diameter vessel. When the probe is aligned against the flow, measurement of velocity is linear to at least 1 m/s. In vivo recordings of coronary and aortic blood velocity are produced by performing a fast Fourier transform (FET) in real time.