Research On The High-resolution Imaging By Fourier Ptychographic Microscopy

Microscopic imaging plays an important role in exploring the microscopic world.With the development of research,great breakthroughs have been made in the field of high resolution and even super resolution.However,there are still many problems in obtaining wide-field-of-view images and measuring phase information.Thanks to the combination with the algorithm,Fourier ptychographic microscopy has become an emerging technique to solve these two problems.The advantage of this technique over conventional microscopic imaging is that a high-resolution,wide-field-of-view image with amplitude and phase can be iteratively reconstructed by recording hundreds of low-resolution images in a simple experimental setup.Nonetheless,the influence of the aberration of the objective lens and position errors introduced by the experimental process on the Fourier ptychographic microscopy cannot be underestimated.Therefore,this paper improves the Fourier ptychographic algorithm from two aspects of the aberration and position errors,and the main work is as following:(1)Considering the pupil aberration of the objective lens and defocusing during the experiment,this paper proposes an improved correction algorithm for pupil aberration.Based on the existing algorithm,updating functions of the sample and the pupil are optimized to fully correct the pupil aberration,and defocus correction is carried out by combining simulated annealing algorithm and deconvolution.At the same time,in order to apply this algorithm into the large-field-of-view imaging system,distortion correction is introduced to solve the lateral chromatic aberration.Both simulation and experimental results show that this algorithm has faster convergence speed and better reconstruction quality in both small and large aberration systems.(2)This paper puts forward the fitting position errors correction algorithm based on the analysis of position errors during the experiment.According to the kinds of position errors in the experiment,the influence of position errors is deduced by formula.The 2D surface fitting with image difference factor was used to determine the actual position before reconstruction.In addition,partial light sources are selected to reduce the time Simulation and experimental results prove that this algorithm not only can reduce the dark lines and fringe inclination introduced by position errors,but also correct the position accurately,which save nearly half of the time.(3)Set up an experimental device to image the resolution testing board and the biological sample,and compare the effect of the existing algorithm with the algorithm proposed in this paper.According to the experimental results,it can be concluded that the proposed algorithm has better stability and better reconstruction quality in practical application.