Laser speckle imaging for blood flow based on pixel resolved zero-padding auto-correlation coefficient distribution

In this paper we present a method of zero-padding temporal auto-correlation imaging (ztDCI) for imaging blood flows. Compared with temporal auto-correlation imaging (tDCI), ztDCI effectively slows down the decorrelation speed of speckle frames, so it has wider applicable speed range. We also prove that the combination of tDCI and ztDCI can compensate the non-monotonous trend of ztDCI VS speed and provides higher relative signal to noise rate (rSNR) for slow flows and short exposure times than laser speckle contrast imaging (LSCI). It captures both slow and fast flows independent of camera exposure time which will be an advantage for in vivo or clinical applications.