High Resolution Transmission Microscopy For Phase Imaging With Ptychographic Iterative Engine (PIE)

As a newly developed CDI (Coherent Diffractive Imaging) method, PIE (PtychographyIterative Engine) is a lenslss imaging technique, which could reconstruct the phase distribution ofthe object with the theories of diffraction, convolution, and Nyquist sampling. PIE was firstlyproposed by John Rodenburg of Sheffield University in2004，and compared with the othertraditional CDI methods, PIE has unique advantages including extendable imaging range, highspeed convergence, and strong noise immunization ability. This thesis is mainly on theoreticalanalysis and experimental researches on the PIE technique when used in the transmissionmicroscopy.PIE technique is applied to an optical microscope by slightly modifying its mechanicalstructure, developing controlling code and data processing software. Reconstruction of biologicalcells is successfully obtained by using10×and20×objectives.According to the sub-pixel image registration algorithm, an improved ePIE algorithm withposition correction is applied to avoid deterioration of reconstructed image induced by thetransverse scanning error. Experimental result confirms the feasibility and effectiveness of thismethod.Based on the analysis of the axial distance error in ePIE with numerical simulation andexperimental research，it is pointed out that the influence of the axial distance error to the imagequality is equivalent to that of the transverse scanning error. By using the position corrected ePIEalgorithm, the image quality degradation induced by the axial distance error can be automaticallycorrected step by step in the iterative reconstruction. And this conclusion is supported by bothsimulations and experiments.