Research On Defocusing Compensation By Shaping Light In Ghost Imaging System

Correlated imaging is a new nonlocal optical imaging technology,also known as ghost imaging,which can reconstruct the image or Fourier transform image of an object by correlating the signals of two optical paths.derapmoC with lanoitidart imaging,correlated imaging has some advantages,such as simple imaging system,nonlocal imaging and strong anti-noise and anti-interference ability.Therefore,correlated imaging has great application prospects in some fields,such as military reconnaissance,atmospheric satellite communication,medical imaging,and so on.In recent years,some internal and foreign researchers have applied light source shaping technology and image processing algorithms to ghost imaging field to improve the quality of ghost-image.In this paper,the influence of shaping light on defocusing effect is investigated deeply in lensless ghost imaging(LGI)and ghost diffraction(LGD)systems,and the influence of compressive sensing on the defocusing effect in ghost imaging is also studied experimentally.The main research content and innovations of this paper are as follows:Firstly,when we study the influence of shaping light on the defocusing effect in lensless ghost imaging system,the defocusing can be obtained by reducing the length of reference arm and keeping the length of test arm unchanged,and shaping light source can be obtained by modulating Gaussian source with hyperbolic cosine function.Based on the theory of correlated imaging,we derive the analytic expression of point spread function of ghost imaging system with hyperbolic cosine Gaussian source in the presence of defocusing.The influence of shaping light on the defocusing effect in correlated imaging can be simply analyzed by the analytical formula,i.e.,the smaller the width of point spread function(PSF)is,the better the imaging resolution of the system is,and vice versa.The numerical simulation results show that the defocusing effect in lensless ghost imaging can be weakened or even inhibited by using shaping light.Secondly,the influence of shaping light on the defocusing effect is also discussed in lensless ghost diffraction system.The numerical simulation results show that the effect of the shaping light on the defocusing effect in ghost diffraction system is similar to that of the ghost imaging system.In the other word,using the shaping light can weaken or even inhibit the defocusing effect in the lensless ghost diffraction.Finally,the effect of compressive sensing on the defocusing effect is studied in lensless ghost imaging system.In the ghost imaging experiment,we replace the correlated imaging image reconstruction algorithm with the reconstruction algorithm of compressive sensing.The experimental results show that when the defocusing length is within a certain range,the defocusing effect in lensless ghost imaging system can be weakened or even inhibited by using compressive sensing technology.However,when the defocusing length exceeds the range,the defocusing effect in ghost imaging can not be weakened by using compressive sensing algorithm.