Extended Depth-of-field Laser Speckle Contrast Imaging System

Laser speckle contrast imaging(LSCI)is a non-invasive,non-contact,wide-field optical coherent domain blood flow imaging technique.It can monitor biological tissue blood flow and vascular morphological changes in real time with the advantage of high spatiotemporal resolution.In recent years,it has shown promising in biomedical and clinical treatment.However,due to the limited depth-of-field(DOF)of optical system,it is difficult to obtain a blood flow image focused in a large field of view,especially for the non-planar biological tissues,which affecting the accuracy of blood flow detection.In this thesis,we combine fast multi-focus imaging and multi-focus image fusion to increase the DOF of the laser speckle blood flow imaging system and improve the performance of wide-field blood flow imaging of non-planar biological tissue.The main research work includes:(1)We propose a fast focusing laser speckle contrast imaging method based on electrically tunable liquid lens,which realizes fast multi-focus laser speckle contrast imaging and achieves fast registration of blood flow images on different focus planes by pre-registration.(2)We design a multi-focus blood flow image fusion method based on contourlet transform,including the analysis of the effect of out-of-focus on blood flow velocity detection and vascular morphology in laser speckle contrast imaging system;the introduction of the fusion process of the multi-focus blood flow image fusion method based on contourlet transform and its fusion result;the comparison of different multi-focus image fusion methods for blood flow image.(3)We design and implement the extended depth-of-field laser speckle contrast imaging system by combining fast focus imaging with multi-focus image fusion to achieve wide-field blood flow imaging detection of non-planar biological tissues.