Research Based On Long-distance Correlation Imaging Properties Of Partially Coherent Light

Correlated imaging is also called as ghost imaging,which is a kind of nonlocal imaging technology.The light source is divided into two distinct optical paths by a beam splitter:one is the object beam which illuminates the target and then is collected by a bucked detector without resolution;the other is the reference beam without target,spread freely after a certain distance which is detected by CCD or point detector for scanning detection.Finally,the output photoelectric currents from CCD camera and bucket detector are sent to a correlator to measure the second-order intensity correlation function which directly gives the image of target.In this thesis,we focus on the practical application of correlated imaging.We study the correlated imaging with partially coherent light and the influence of turbulent atmosphere on correlated imaging with partially coherent light.This thesis includes five parts,of which the main contents are as follows:In part one,firstly,the basic concept of correlated imaging are introduced briefly,then from the HBT experiment,we introduce the second order intensity correlation,and review the history and current situation of the correlated imaging.Finally,we make a comparison between the traditional optical imaging and correlated imaging.In the second chapter,we focuse our attention on the introductions of correlated imaging with quantum entangled light and thermal light respectively,correlated imaging,thermal correlated imaging and the applications of correlated imaging.Among the applications of correlated imaging we introduce reflective correlated imaging,correlated imaging through atmospheric turbulence and ghost imaging lidar.In the third chapter,we study correlated imaging with partially coherent light for long-distance.Based on the generalized Huygens-Fresnel integral and the theory of coherence of light,we derive the transverse normalized second-order intensity fluctuation correlation function.Then,according to numerical calculations of the second-order intensity fluctuation correlation function,we study the imaging performance.It is found that large object lens and small transverse coherence length of light source are necessary for obtaining high resolution of the image.And the magnification of the image only depends on the propagation distance.As comparing with the lensless correlated imaging,the resolving power is independent on the size of light source,and the light source's aperture only determines the field of view in the object plane.In the fourth part,we investigate the effect of turbulent atmosphere on correlated imaging with partially coherent light.By using the generalized Huygens-Fresnel integral and the quadratic approximation of the structural function,we can obtain the second-order intensity correlation function for the correlated imaging in atmosphere.By numerical simulations we study the influence of atmospheric turbulence,propagation distance and some coherent light parameters to the visibility and resolution.In addition,we can find that atmospheric turbulence between the target and collection lens has little influence on the imaging properties.In this imaging system,the target can be far away from the local reference and collecting systems.Hence,the correlated imaging with partially coherent light studied here is suitable for remote sensing through the turbulent atmosphere.The finally is the summary and expectation.