Optimization Research On Asymmetric-arm Ghost Imaging Experiment

Ghost imaging,also known as correlated imaging or quantum imaging,is a new imaging technology,which has the characteristics of indirect imaging and off-object imaging.At present,ghost imaging technology mainly focuses on the types of light sources,reconstruction algorithm,modulation mask and practical application,and has made great breakthroughs.Compared with the classical imaging system,thermal light ghost imaging has stronger anti-jamming ability,and the resolution is separated from the field of view.At the same time,the Fourier transform image of the object can be obtained in the near field without using the lens.Pseudo-thermal light source simulates the statistical properties of thermal light source well.It can be fabricated by laser irradiation of moving scatterers,and its transverse coherence length can be adjusted by changing the experimental parameters.Therefore,it is widely used in various ghost imaging experimental systems.Firstly,the principle,simulation method,evaluation method of transverse coherence scale and classical image quality evaluation index of pseudo-thermal ghost imaging are introduced at the beginning of this paper.Then,focusing on the design of the experimental system for ghost imaging with pseudo-thermal light source,the experiments of ghost imaging with symmetrical and asymmetrical arm are carried out successively.The experimental results show that these schemes are reasonable.Aiming at the problems of energy dispersion,large field of view and atmospheric turbulence in the scene of long-distance reflective objects,a scheme of using high power laser at the transmitter and a combination of large-aperture reflective astronomical telescope,photomultiplier tube and narrow-band filter at the receiver has been adopted,and good experimental results have been achieved.In the last part of this paper,a data preprocessing scheme based on Schmidt process is proposed to remove the redundant information of light field in time and space,aiming at solving the problems of long reconstruction time and poor image quality.The simulation results show that the scheme can achieve a high signal-to-noise ratio under ideal conditions.However,the subsequent noise analysis results show that noise and error will deteriorate the image quality under large sampling,which is verified by subsequent experimental data.By grouping the measured data in advance,the influence of noise can be reduced and the robustness of the system points can be enhanced.