Self-mixing laser speckle velocimeter for blood flow measurement

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 activity of the blood flow in a certain probing area. The experimental results show that this new type of speckle velocimeter can be useful for the relative evaluation of blood flow in human tissues.