Measurement Of Disordered Media Transmission Matrix And Study Of Light Focusing Imaging

Imaging the inside of biological tissues is an important research topic in the field of biomedicine.Current medical imaging methods have the disadvantages of low imaging resolution,shallow imaging depth,and invasiveness.The wavefront shaping method has the advantages of deep imaging depth and high imaging resolution after imaging the disordered medium.Biological tissue is also one of the disordered media,so the wavefront shaping method has broad application prospects in the field of medical imaging.And the wavefront shaping method uses visible light or near-infrared light as light source,and is not invasive to the human body.Therefore,the wavefront shaping method is very important for the recovery of the pattern after the disordered medium.In this paper,the transmission matrix method in the wavefront shaping field is deeply studied.The sequential semi-definite programming method(SSDP)and the modified co-propagation interference method are proposed to measure the transmission matrix of the disordered medium.The feasibility of the two methods is verified by simulation and experiment,and the measured transmission matrix is used to focus the light after the disordered medium.Compared to the semi-definite programming method,the sequential semi-definite programming method has a significant reduction in measurement time,number of measurements,and computer memory cost.The modified co-propagation method improves the accuracy of measuring the transmission matrix of the disordered medium.Based on the disordered medium transmission matrix measured by the modified co-propagation method,we use the focus point scanning method to recover the pattern after the disordered medium,then use the denoising algorithm to denoise.The Pearson correlation coefficient reaches 0.78 between the recovered image and the original image.However,considering that focus scan imaging requires extra time and there is noise during the scanning process,we have proposed a new method that can recover the pattern directly from the measured transmission matrix.The recovered pattern is processed by the denoising algorithm.The Pearson correlation coefficient reaches 0.82 between the recovered image and the original image.