Research On Theory And Key Techniques Of Computational Optical Microscopy Imaging

With the rapid development of computational optical imaging theory and technology,the computational optical microscopy technology,which is derived from the combination of computational optical imaging techniques and conventional microscopes,opens a new window for advancing the conventional microscopy.Computational optical microscopy is able to achieve higher quality images with a simpler optical system with the assistant of computational optical imaging technology and further bring novel imaging function,which are difficult to achieve with the conventional microscopy.Light field microscopy is one kind of computational optical microscopy,which has large field of view and fast three-dimensional microscopic information acquisition capability.It can simultaneously record the spatial and angular information by using a two-dimensional image sensor,and then obtain perspective images,digital refocusing and other new imaging functions by different post-algorithm.In this thesis,the author firstly review the research status of computational optical microscopy at home and abroad.Several works are presented in this doctoral dissertation to explore the key theories and related new methods associated with light field microscopy.These works have important theoretical significance and application value.The main research work and contributions are summarized as follow:1.For the light-field-based phase imaging,LF-TIE phase imaging method has been proposed,which is the combination of transport of intensity(TIE)equation phase imaging method and light field microscopy(LFM).Based on the ability of fast three-dimension acquirement of LFM,we can get two intensity images at different defocus distances by using the digital refocusing algorithm of the light field.Hence,LF-TIE can realize single-shot phase imaging without moving the camera or sample in the experimental system.2.For the severely low-frequency cloudy noise problem in the two-plane intensity light-field-based phase imaging,light field digital refocusing based optimum frequency combination method has been proposed.Meanwhile,this method is combined with the exponential spacing measurement scheme to choose the optimum defocus distances,which helps us to achieve high single-noise-radio(SNR)phase imaging with fewer intensity images.The multi-plan intensities can be obtained by the digital refocusing algorithm.Hence,our method can realize single-shot phase imaging with high SNR,which is also efficiently solves the contradiction between low-frequency cloudy noise problem and high-order nonlinearity errors.3.For the limited of spatial resolution of LFM,the light-field moment microscopy(LFMM)with noise reduction has been proposed.This method solves nonlinearity errors and noise problem in the conventional light field moment imaging by using least squares fitting with multi defocused intensity images to suppress noise and improve the accuracy of the computational reconstructed 4D light field.The computational reconstructed 4D light field has full-resolution due to obtain it without microlens array.4.A unified endoscopy system based on light field microscopy has been introduced.By inserting a microlens array into the optical train of a conventional endoscope,a light field endoscopy is built,which is able to capture three-dimensional information with conventional endoscopy without complex optical system design.This method avoids the problems such as the expensive cost and complex design of an optical system in the conventional 3D endoscopy.The experimental results have demonstrated that the light field endoscopy is able to obtain the focal stacks from a single-shot light field image by the digital refocusing algorithm.We also analyze the relationship between its optical parameters and the spatial resolution,angular resolution,depth of field of this system,and then show this relation by equations.