Super-resolution Imaging By High-order Optical Intensity Auto-correlation Of Filtered Incoherent Light

Breaking through the diffraction limit to obtain higher resolution of the image has a very important significance in the research and development of physics,biological science,medicine,materials science and computer and other fields.Diffraction limit usually refers to the fact that an ideal object point is limited by the finite aperture of the system when it passes through the actual optical system for imaging,so the ideal image point cannot be obtained,but a Fraunhofer diffraction image can be obtained.This greatly restricts people from seeing the smaller details of the imaged object,and "seeing" smaller has become a bottleneck in many research fields.Therefore,breaking the limitation of the diffraction limit and realizing super-resolution imaging is a technical requirement for the continuous development of social economy,and it has also become one of the eternal topics in many fields of scientific research.Since the related imaging of thermal light source was discovered at the beginning of this century,both theory and experiment have made great progress.The random speckle illumination generated by pseudothermal light source can prove the sub-Rayleigh limit imaging of objects in incoherent imaging system under certain conditions.On this basis,Super-resolution imaging by high-order optical intensity auto-correlation of filtered incoherent light is carried out by adjusting the appropriate random speckle.Under the premise that the second-order self-correlation still cannot break through the diffraction limit,the method of high-pass filtering surpasses the traditional Rayleigh diffraction limit,and achieves the super-resolution imaging.In order to further optimize the imaging scheme and obtain better imaging quality,this paper continues to study the experimental scheme combining high-pass filtering and high-order imaging.The experimental images obtained are compared with the results of direct filtering and the experimental results of second-order self-correlation,third order,fourth order and fifth order respectively,and it is found that the combination of the two can achieve better super-resolution imaging.The introduction of high-order autocorrelation measurement in the experimental process can achieve higher resolution,but increasing the order of correlation measurement will reduce the signal-to-noise ratio of imaging,so with the increase of the number of correlation measurement,longer integration time is needed to obtain clear super-resolution imaging.In addition,the contrast of correlation imaging can be improved by using the high-order intensity fluctuation correlation theory,and the high-order imaging is combined with the filtering correlation imaging,and the filtering plays a major role.The application of the above theories can further improve the autocorrelation super-resolution imaging of real objects,and bring a certain application prospect for the improvement of resolution related fields.