Depth measurement of a blood flow region based on speckle decorrelation

Laser speckle technique is a useful means for imaging blood flow in living bodies and, it has been utilized for analyzing the condition of living bodies or the health state. However, depth of a blood flow region has not been measured yet by this method. In the present study, we investigate use of a decorrelation in a pair of speckle patterns in a temporal sequence for measuring depth of the blood flow region. Blood flow is also measured simultaneously by means of a spatio-temporal difference of the same pair of speckle patterns as that used for depth measurement. Experiments are conducted for reference and sample models using ground-glass plates and a silicone layer and for a human finger, to confirm the feasibility of the proposed method.