<unk>  <unk>  is an<unk>  method that uses a<unk>  beam to scan live tissue. When the<unk>  light reaches the tissue, the moving blood cells generate<unk>  components in the reflected (backscattered) light. The light that comes back is detected using a photodiode that converts it into an electrical signal. Then the signal is processed to calculate a signal that is proportional to the tissue perfusion in the scanned area. When the process is completed, the signal is processed to generate an image that shows the perfusion on a screen. The<unk><unk>  effect was first used to measure microcirculation by Stern M.D. in 1975. And it is used widely in medicine, some representative research work about it are these:
Laser Doppler imaging
Laser speckle contrast imaging
Digital variance angiography
Microangiography
Acoustic angiography
Intravascular fluorescence
Colorimetric capnography
Doppler ultrasonography