A velocimeter using speckle phenomena in self-mixing laser diodes (SM-LDs)
is used to evaluate the blood flow noninvasively, The mean frequency of the
speckle signal obtained from the self-mixing laser diode reflects the acti
vity of the blood now in a certain probing area. The experimental results s
how that this new type of speckle velocimeter can be useful for the relativ
e evaluation of blood flow in human tissues.