A NEW SINGLE-FIBER LASER-DOPPLER FLOWMETER BASED ON DIGITAL SIGNAL-PROCESSING

A new laser Doppler flowmeter, based on a personal computer with a dig ital signal processor for detecting the blood perfusion zn skeletal mu scle, was designed and evaluated. An infrared laser diode (750 nm) fed a single optical fibre, 400 mu m in diameter, which was introduced in to the muscle. A PC equipped with a digital processing unit was used f or emulation of the laser Doppler algorithm and for presentation of th e measurement results. The Doppler signal power spectral density and c orresponding flow values were visualized on the computer screen contin uously in realtime, and could also be saved on the hard disk for off-l ine analyses. The graphic-user interface supported by Labwindows softw are made the system easy to use It is possible to alter in the softwar e the signal processing and the ways In which the signals and results are presented. The new system was evaluated by using a flow model as w ell as a mechanical model. The model studies showed linear relationshi ps between particle velocity and flow in the range of Od mm s(-1). The system was also tested in measurements of the blood flow in the brach ioradial muscle, and was found to have advantages over our previously used systems. Copyright (C) 1996 Elsevier Science Ltd for IPEMB.