Laser Doppler Flowmetry (LDF) is a noninvasive diagnostic method to measure blood flow in tissue [1]. The technique is based on measuring the Doppler shift induced by moving red blood cells to the illuminating coherent light. A laser Doppler instrument often gives output signals related to the flux, velocity and concentration of the moving blood cells. These parameters are extracted from the power spectrum of the intensity fluctuations produced by a photodetector. There are two types of perfusion instruments in practice, the laser Doppler perfusion monitor (LDPM) and the laser Doppler perfusion imager (LDPI)
