Computational Scattering Imaging Key Techniques Based On Optical Phase Retrieval

The technology of imaging through the scattering media has been the focus of research in the field of optical computational imaging in recent years,which has important application prospects in many fields,such as military reconnaissance,fire search and rescue,automobile autopilot,underwater imaging,medical detection,etc.There are many methods used to solve the problem of strong scattering imaging,but these methods have their own advantages or disadvantages.The scattering imaging technology based on optical phase retrieval has better development prospects,and is expected to achieve better imaging with a large field of view,long distance,and high quality.In view of the common problems in scattering imaging technology based on optical phase retrieval,the thesis starts with two representative techniques of optical phase retrieval,Coherence Diffraction Imaging and Fourier Ptychography,and faces some practical demand of scattering imaging application scenarios.Through the fusion of methods and technology,this word can achieve technical framework design and algorithm improvement,and propose practical optical scattering imaging technology which has been verified by simulations and experiments.The main research work is as follows:1.The method named single-shot coherent power-spectrum scattering imaging is proposed and verified,based on the basic principles and implementation methods of optical phase retrieval.An optical experimental platform is designed and built based on the optical path of coherent diffraction imaging.The linear relationship between the ideal power-spectrum of the target and the actual scattering power-spectrum is derived using the theory of light propagation,combining the optical memory effect and Wiener-Khinchin theorem.This linear relationship becomes the theoretical basis of the technology of single-shot coherent power-spectrum scattering imaging.Experimental results show that this method can quickly reconstruct a clear image of the object hidden behind the scattering media with only one acquired power-spectrum image.2.The technology of single-shot coherent power-spectrum scattering imaging is improved,and the object with complicated structure hidden behind the scattering media is rapidly reconstructed by one-shot power-spectrum.The factors affecting reconstruction performance are analyzed,include the influencing factors of data source and algorithm process.And then a frequency-domain enhancement method that dynamically adjusts the feedback parameter and nonlinear modulus are proposed respectively,which optimize the single-shot coherent power-spectrum scattering imaging.The optimized method can effectively accelerate the convergence rate of the algorithm,improve the quality of image reconstruction,and achieve the scattering imaging of objects with more complicated structures.3.The method named variable-aperture Fourier ptychography used in scattering imaging is proposed and verified by the experiments.According to the method of aperture scanning Fourier ptychography,the variable-aperture Fourier ptychography is suggested,and its process is designed to complete the simulations and experiments of scattering imaging.The results verify that this technology takes less time to recovery and the reconstruction quality is better,and the new method has strong robustness to the aperture position and shape errors.This technology is suitable for scattering imaging of complicated structures with a wide field of view.4.The method termed single-shot scattering imaging based on soft aperture-scanning Fourier ptychography is proposed and verified.In view of the shortcomings on hardware scanning in the technology of Fourier ptychography scattering imaging,such as time-consuming and high requirement on mechanical hardware,and the problems of blurring are still common in single-shot coherent power-spectrum scattering imaging,a soft aperture-scanning Fourier ptychography is firstly proposed to strengthen the frequency-domain constraints in the optical phase retrieval algorithm.The experimental results show that this technology can realize fast and high-quality scattering imaging,and it is helpful to expand the Fourier ptychography to the application field of scattering imaging with higher real-time requirements.In short,the computational scattering imaging based on the optical phase retrieval can realize fast and high-quality image reconstruction of the target with more complicated structures through the scattering media under coherent light illumination,which can effectively overcome the common limitations existing in the technologies of scattering imaging,such as time-consuming,deblurring,narrow field of view,and harsh experimental conditions.The technology studied in this thesis has important reference value for solving the basic application problems in optical scattering imaging.