Study On Light Scattering Properties Of Biological Tissue Based On Digital Holography

With the development of photoelectric technology and computer technology,quantitative phase imaging technology is widely used in medical diagnosis and biological research.Quantitative phase imaging based on digital holography is one of the most rapidly developing microimaging techniques in recent years.The quantitative phase measurement of cells or tissues by digital holography has the advantages of lossless,contactless and no staining.In this paper,we study the light scattering properties of biological tissues and measure the refractive index of biological cells based on digital holography.The main contents include the following aspects:1.We propose a method extracting high-precision phase distribution of biological tissues.Firstly,object wavefront is reconstructed using the numerical reconstruction algorithm from digital hologram.Secondly,Zig-Zag scanning is introduced to reorder the object wavefront from matrix to 1D vector,allowing the retrieved phase value to change smoothly without value saltation.Then,1D lateral shear process is performed to acquire the shear vector,from which the phase difference vector is extracted by arctangent calculation.Afterwards,the phase vector is obtained through numerical accumulation.Finally,the real phase distribution matrix is retrieved by inverse Zig-zag scanning.The proposed method has high precision in phase extraction of biological tissues.2.We propose a method combining off-axis digital holography(DH)with the scattering phase theorem to measure the scattering characteristics of biological tissue.First,we construct a light scattering measurement system of biological tissue based on the Mach Zehnder interferometer and CCD record the digital hologram of normal bladder and cancerous bladder tissue.Then,the hybrid reconstruction algorithm is introduced to obtain the quantitative phase imaging of the tissues,from which the scattering parameters are calculated.Finally,mathematical statistical tools are used to quantitatively characterize the difference in light scattering characteristics between normal bladder tissues and bladder cancer tissues.The results show that the light scattering intensity of cancerous bladder tissues is stronger than that of normal tissues.3.This paper deals with the measurement of refractive index of cells based on digital holography.We construct a digital holographic microscope to measure the quantitative phase imaging of suspended macrophages.Then approximate modeling is used to evaluate the thickness,spherical macrophages are fitted into spheres,and the inner refractive index distribution of the two macrophages is measured and the mean value is calculated.In addition,the variation of refractive index and phase in macrophages with time is also studied.The experimental results show that with the process of macrophages apoptosis,the refractive index of cells presents a decreasing trend,and the peak value of cell phase gradually decreases.