The Research Of The Single-beam Phase Retrieval Technology

Phase retrieval is a technology which can reconstruct phase from the intensity distribution.The information of phase can carry a lot of information of the object, such as shape, refractiveindex and so on. The information is retrieved from the phase in many applications, so the phaseretrieval technology is quite important. Digital holography and single-beam wave-frontreconstruction technology are the main method of phase retrieval nowadays. Holographytechnology is conducted by interfering the object wave-front with a known reference. Phase canbe retrieved from those interference patterns. Nowadays, digital holography technology has beenwidely used in different fields of optics such as microscopy deformation analysis, measurementof stress field distribution and temperature field etc. However, due to the interference inholography, it needs coherent light, which limits the application of holography. In a single-beamwave-front reconstruction technique, phase is reconstructed form the measured intensity indifferent planes and then according to the principle of diffraction, phase can be reconstructed byusing the phase retrieval algorithm. The technology does not need to use interference. It canovercome the shortcomings of holography. What’s more, the device is particularly simple, so thepotential of this application is very great. The technology can be applied to the imaging field ofincoherent light source (such as x-ray). However, the accuracy of the phase retrieval technologyby single-beam wave-front is relatively poor, which makes the technology far from the widelyused, so further study should be made to improve the accuracy of the phase retrieval.In this paper, the technology is proved by simulation and experiment. Quantitative andqualitative analysis are made by simulation and experiment respectively. The work of this papercan be divided into the following four parts:1. The development and application of phase retrieval are introduced. Two method of thetechnology—holography and single-beam wave-front reconstruction technique areemphatically introduced. The advantages and disadvantages of two technologies arecompared.2. The basic theory in the single-beam wave-front reconstruction technique is expounded,including Fresnel diffraction theory, Fraunhofer diffraction theory and angular spectrumdiffraction theory. The iterative algorithm of the technology and the auxiliary equipmentinvolved in the experiment are introduced. 3. The simulation of this technology is made by Matlab. Six parameters of the single-beamwave-front reconstruction technique are studied. The six parameters are the number ofimpling planes, the round trip number of iterative, the initial phase, the distance betweenthe object and the first sampling plane, and the distance between sampling planes. Theeffects of each parameter to the reconstruction are quantitatively analyzed by comparing thesum-squared error. We can not only prove the feasibility of this technology in theory, butalso optimize the parameters selected in the experiment.4. How the parameters effect the reconstruction is studied by structuring optical path, doingexperiment, collecting intensity distribution in different planes, setting different parametersand observing the experimental results. In the end, error is analyzed.