Research On Stacked Diffraction Imaging Method Based On Three-wavelength Illumination Aperture Modulation

Phase distribution of light wave contains a lot of information such as internal structure.How to retrieval phase by algorithm is a focus in computational imaging field.Ptychographic iterative engine(PIE)is a phase retrieval method with no lens,no reference light and non-interference,which scans the object through a localized illumination probe to a raster of positions and records all the diffraction patterns formed in the far field,can reconstruct the transmission function of the sample accurately and rapidly with iterative calculation from the recorded diffraction patterns array.However,2-D moving process introduces scanning position error that affects the accuracy of retrieval,what is more,the image acquisition process takes a long time.This study focuses on the theoretical mechanism and error model of the PIE.The main research contents of this paper are summarized as follows:Phase imaging and measurement related methods are studied.The principles,advantages and disadvantages of phase contrast phase imaging technology,digital holography technology,Hartmann wavefront measurement technology and light intensity transmission equation technology are summarized.The advantages,development history and current problems of the PIE phase recovery method are elaborated and summarized.The imaging principle and retrieval algorithm of PIE and its extended algorithm ePIE are studied through numerical simulation and analysis.The core error factor affecting the imaging accuracy of PIE—scanning position error,is quantitatively explored.An annealing algorithm to correct positioning errors in ptychography(pc-PIE)can theoretically eliminate the scanning position error to a certain extent through reproduction and prove,but data calculation will increase several times.A new phase retrieval algorithm named tri-wavelength probe space modulation ptychographic iterative engine(tpsm-PIE)has been proposed and studied.The method proposed realizes spatial correlation by modulating the range of illumination pupil without mechanical scanning movement.Frequency range of illumination is extended by increasing the number of incident wavelengths,and the data redundancy is improved at the same time.Color CCD instead of monochrome CCD is used to increase the information recording efficiency by 3 times.The feasibility and core parameters of the method are verified and analyzed respectively,and relevant correction methods are proposed for the error factors existing in the system.Optical experiments are set up.The verification experiment on the USAF-1951 resolution plate shows that the spatial resolution of the algorithm reaches 12.4?m.Biological samples and optical glass are used as experimental samples respectively.The experimental results show that the proposed method can restore the phase of mosquito leg slice and the step height information of CGH with high quality,meaning methods proposed can apply to the fields of biological quantitative phase imaging and optical measurement.This paper starts from simulation and experimental two aspects,verifies the feasibility and advantages of the phase recovery method proposed,expands the comprehensive performance of PIE technology,and can be applied to the fields of biological quantitative phase imaging and optical measurement.