Sub-Rayleigh Resolution Imaging Based On High-Order Intensity Correlation Of Thermal Light

Traditional imaging utilizes the first-order correlation of the light field while the quantum effects of the entangled two-photon sources discovered by scientists in recent years,such as correlation imaging,which is related to spatial intensity correlation,is achieved by the second-or higher-order correlation of the light field.Because the diffraction limit of the imaging system restricts the resolution of the imaging,thereby limiting the further development of high-resolution imaging techniques,imaging techniques that surpassing diffraction limits to obtain high-resolution images has a very wide range of application value in the biological sciences,medicine,computer and other electronic image field.In this paper,the sub-Rayleigh resolution imaging experiment in traditional lens imaging system is realized by using the high order intensity fluctuation correlation method.In the experiment,by adjusting the speckle size and the diameter of the imaging system,we carried out arbitrary high-order intensity fluctuation self-correlation in the experimental conditions of magnified image and the equal image when the bad image quality(a blurred image)is obtained by the second-order self-correlation imaging.The experimental results show that the high-order self-correlation method for the non-coherent light source has higher imaging resolution than the second-order one,and the higher the order,the higher the resolution and the better the image quality.We further use the correspondence imaging method combined with high-order self-correlation imaging scheme to process the above experimental data.This method is that instantaneous optical intensity is splitted into positive and negative groups according to the instantaneous optical intensity fluctuations more than and less than 0,and then two groups of data were respectively used to reconstruct the image by the high-order self-correlation method.It is found that the restored image is the positive and negative image of the object to be measured at the odd order,and only positive image is obtained when the order is even.By comparing the positive and negativeimages obtained by the experiment,it is proved that this method can also break the diffraction limit,and less experimental data to restore the image of the object to be measured is less needed because the correspondence imaging method can filter out the less fluctuation data.Compared with the traditional correlation imaging,the correspondence imaging method is simple and just groups the data and then average them,which can effectively save time.