Research Of Phase Unwrapping Used In Dynamic Digital Holography

Dynamic digital holography brings a great of convenience to some real-time,online, quantitative detection and analysis. It has a brilliant prospect for application,and has become a hot spot in related research. It can make a holographic record forevery transient process of dynamic object. The phase information calculated by digitalreconstruction is wrapped phase. Therefore, the problem of phase unwrapping isubiquitous and tough in dynamic digital holography.Based on the phase unwrapping for static and single hologram, and therequirement for real-time, online detection and analysis of dynamic digital holography,in this paper, a fast phase unwrapping algorithm used in dynamic digital holography ispresented. The theoretical and experimental research has also been done.Firstly, the theory and procedure of phase unwrapping is discussed from differentdimension. Based on static and single hologram, the fundamental principle of severalkinds of phase unwrapping algorithms has been analyzed in detail. The experimentalresults have been studied.For multiple of dynamic holograms, in this paper, we find out the inaccuratepoints affecting unwrapping accuracy while fully considering phase unwrappingaccuracy and run time, make some marks for them, and then use center radiationphase unwrapping algorithm, which has relatively fast operating speed to bypass theseinaccurate points. In order to solve relevance problem in time domain for phase valuesof different frames and phase unwrapping problem for inaccurate points enclosed area,we use the relevance in time domain of dynamic digital holograms after setting theunwrapping path in time domain.Finally, the proposed algorithm is applied to the evaporation of small water dropsand a moving larva. For dynamic and numerous holograms, this algorithm isreasonable and effective. It has a fast speed, automatic and high accuracy in phaseunwrapping.