Phase Retrieval Algorithm Based On Non-interferometry Optical Filed

Due to the light frequency is too high, the existing equipment can only collect the intensity information of the optical field, but can not obtain the phase information directly, so we need to use the intensity information to restore the phase information of the light filed. The research of phase retrieval algorithm is important for many fields, such as astronomy, X ray phase contrast imaging, diffractive optic, holography, wave-front reconstruction and so on. But the interferometry from intensity measurements in recovery phase requires the continuing space and time of light source, which will causes a series of problems such as resolution, sensitivity and so on. So we researched the phase retrieval algorithm which is based on the non-interferometry optical field. Non-interferometry phase retrieval technology mainly includes the deterministic solving which based on the intensity transport equation(TIE) and iterative. The main research work are as follows:First of all, this thesis researched the deterministic solving phase information based on the TIE equation. We summarized the various solutions of the TIE equation, such as Fourier method, multigrid method and so on. We focused on the Fourier method, discussed the imaging distance parameter influences, and this algorithm has a fast calculation speed, which is good for low-frequency information recovery, but what it gets is the approximate solution of the phase. Through the simulation and real experiments, it is applied to the near filed.Secondly, we researched the iterative algorithm. We summarized the various iterative algorithms, such as GS iterative algorithm, the angular spectrum iterative algorithm and so on. We focused on the angular spectrum iterative algorithm, the idea is using the random phase as the initial iteration phase, exploiting plane angular spectrum communication principle, iterating between the object plane and image plane, finally getting the message of the object phase. Through the simulation experiment, the algorithm is good for the high frequency information recovery, but only fit for the far filed.Moreover in order to overcome the limitations of the TIE method and iterative algorithm, we combine these two, that is using TIE solution replacing the iterative initial phase. Through the simulation and real experiments, this algorithm can improve the accuracy of retrieval phase using TIE equation, while reduce the computational burden and extend the scope of application of imaging distance.Finally, based on the TIE, iterative and the combination of TIE and iterative algorithm, this thesis presented the phase retrieval algorithm model which based on the non-interference optical filed. We used the TIE equation algorithm in the near field, the combination of TIE and iterative algorithm in the midfield, the iterative algorithm in the far field. Through the simulation experiment, we testified the algorithm model is good for different imaging distance phase retrieval.