Influence Of Speckle Field Properties On Imaging Quality In Correlated Imaging

As a new imaging technology,correlated imaging,or ghost imaging(GI),has received extensive attention from scholars at home and abroad in recent years.The novelty of its imaging mode,along with its anti-atmospheric turbulence and anti-scattering features,make it hold great application prospects in practice.Correlated imaging can be achieved either by coincidence counting using an entangled light source,or by high order correlation using a classical source,such as pseudo-thermal light.In recent years,benefiting from the development of computational ghost imaging,the speckle field applied in classical correlated imaging has turned to have more options than ever,which can be obtained by a spatial light modulator or a projector,following negative exponential distribution or 0-1 distribution and so on.In this dissertation,we work on the influence of speckle field properties on imaging quality in the correlated imaging.Firstly,we introduce the propagation of light,the statistical properties of light and the correlation function,and we deduce the relationship between the transverse coherence scale and the reconstructed image resolution.We also present three commonly adopted algorithms—traditional ghost imaging,differential ghost imaging and compressive ghost imaging.Secondly,we discuss how the mean and variance of the speckle field can influence on the imaging quality,by means of numerical simulation.Then we study on influence brought by the statistical properties of the speckle field on the imaging quality,by comparing the results when the speckle field is under normal distribution,negative exponential distribution,uniform distribution and binary 0-1 distribution respectively.The results show that,under the ideal condition,the mean,variance and statistical distribution of the speckle field do not affect the imaging quality,as long as the random fluctuation exists in the speckle field.Furthermore,considering the threshold and dynamic range of bucket detector,the variance of the speckle field has a significant effect on the correlated imaging quality.The optimal speckle field is given under the premise of knowing the parameters of the bucket detector.Finally,an optimized speckle field,a hybrid of different transverse coherent scales,is proposed.The numerical simulation results show that the imaging quality can be significantly improved using the speckle field,compared with the speckle pattern with a single transverse coherent scale.