Study On Some Problems Of Correlated Imaging

Unlike conventional imaging,correlated imaging is a novel imaging technique which reconstructs the image of an object by means of intensity correlation measurements.Recently,correlated imaging has attracted many researchers attention,and the results show that correlated imaging could be applied to three-dimensional imaging and remote sensing et.al.In order to promote the application of correlated imaging,it is necessary to study how to improve the quality of correlated imaging.Thus in this thesis,we study the influence of the degree of polarization and atmosphere turbulence et.al.on the image quality of correlated imaging,respectively.In the first two chapters,we give a brief introduction of the research progress and basic theory of correlated imaging.In the third chapter,the influence of speckle size on the image quality of transmissive correlated imaging is investigated both theoretically and experimentally.An expression for the contrast-to-noise ratio(CNR)of transmissive correlated imaging is derived.We study experimentally the influence of speckle size and number of measurement on the CNR of correlated imaging via the lensless correlated imaging scheme.The results show that,when the number of measurement is fixed,the larger the speckle size,the better the correlated imaging quality(CNR)becomes.Moreover,as the speckle size remains unchanged,the larger the number of measurement,the better the correlated imaging quality(CNR)becomes.In the fourth chapter,we study the influence of the degree of polarization(DOP)on the image quality of transmissive correlated imaging both theoretically and experimentally.According to the statistical properties of thermal light,we achieve the theoretical relationship between the DOP and CNR.The theoretical analysis shows that,when the ratio of object size to the speckle size is small,a large of DOP value will lead to a low CNR.We also investigate experimentally the impact of DOP of pseudo-thermal light on the CNR.The experimental result is consistent with the theoretical analysis.Furthermore,the theory analysis also shows that the image quality is insensitive to the DOP of thermal light as long as the object size is much larger than the speckle size.In the fifth chapter,we study theoretically the influence of atmosphere turbulence on the image quality of reflective correlated imaging.An expression for the CNR of reflective correlated imaging is derived.The theoretical analysis shows that the atmospheric turbulence has slight effect on the CNR of correlated imaging.Our results illustrate that,in practical situations,the CNR of correlated imaging is still robust even if there are atmosphere turbulence and depolarization caused by the scattering.This results could be more valuable in the remote sensing with correlated imaging.