Phase Retrieval From Hologram By Using High-order Transport Of Intensity Equation

Highly reliable measurement and analysis for phase reconstruction of phase objects are currently widely used in the optical field.Transport of intensity equation and digital holography are typical representatives of non-interferometry and interferometry in phase measurement methods,respectively.But both of them have their own shortcomings in the reconstruction process.The former often uses a mobile external device to obtain two intensity patterns,which has low accuracy,is prone to non-linear errors and is not suitable for measurement of uneven light intensity distribution.The limitation of the latter is that the reconstructed phase information generally needs to be unwrapped and the phase depth is limited.The unwrapping operation.This paper combines transport of intensity equation with digital holography to carry out the research on phase retrieval from hologram by using high-order transport of intensity equation(DH-HTIE),that is,the use of digital holography's numerical focus function reconstruction multiple intensity patterns are used as the input of high-order transport of intensity equation,combined with accurate transport of intensity algorithms,to achieve phase reconstruction under non-uniform light intensity.The main work of this paper is reflected in the following items:(1)Phase retrieval theory based on high-order transport of intensity equation.Analyze the basic principles of the multi-plane-based high-order transport of intensity transmission method and the algorithm to solve the phase difference in the non-uniform light intensity,combined with the advantages of digital holography reconstruction,propose a hologram phase retrieval algorithm based on the accurate high-order light intensity transmission equation,effectively enhance the noise immunity and accuracy of the light intensity transmission equation and improve the phase reconstruction ability;(2)The simulation research on phase retrieval from hologram by using high-order transport of intensity equation;simulation analysis of the reconstruction process of DHHTIE method,the optimal number of defocused images and the optimal axial deviation distance.Compare and analyze the phase reconstruction results of digital holography and traditional TIE method,and study the phase recovery under different phase structures,phase profiles and phase depths.The results show that the DH-HTIE method has higher reconstruction accuracy and is more suitable for the measurement of largesize phase objects;(3)Experimental research on phase retrieval from hologram based on high-order transport of intensity equation.In this paper,a digital holographic recording optical system is constructed,and phase retrtrieval experiments are carried out using standard resolution plates,large-size spherical phase object and GRIN fiber as samples.The experimental results show that the hologram phase retrtrieval method based on the highorder transport of intensity equation can effectively realize the reconstruction of objects with larger phase depth and can effectively eliminate the secondary phase error introduced by the microscope objective.