Super-resolution Band-pass Filtered Ghost Imaging With Compressed Sensing

Quantum imaging,also known as correlation imaging or ghost imaging(GI),is a recently newly-developed technique,which can recover the spatial information of an object via second-order intensity correlation measurement of spatial light field.This non-local GI technology has various novel advantages for practical applications compared with traditional imaging: 1.It can recover the spatial information of an object without lens which is in principle suitable for any wavelength in electromagnetic spectrum;2.It allows imaging of an object in rather bad environments such as in a scattering medium or turbulent atmosphere;3.Under the same conditions,GI has a much higher resolution than that of traditional lens imaging.Therefore,GI has great potential application in various fields,such as national defense,military,remote sensing,communication,biological microscopic imaging and so on.However,GI has some limitations of low visibility,low signal to noise ratio(SNR)and long integration times,which also hindered the application of GI in real life.In this paper,on the basis of the traditional GI experiment we propose the band-pass filtered GI(FGI).To further verify the superiority of this method,we compared band-pass FGI with the traditional GI,low-pass FGI and high-pass FGI.In a lens-less GI experiment performed with spatial band-pass filtering,the spatial resolution can exceed the Rayleigh diffraction bound by more than a factor of 10,and the resolution value is about one pixel.At the same time,the visibility can almost be as good as 100% under a certain condition,which is much better than the visibility limit of 1/3 in a traditional GI.To reduce the sampling number and enhance the image quality,compressed sensing(CS)is also employed,and the experimental results also show that FGI plays the key role in the improvement of resolution and not CS.In order to improve the SNRs,we propose an iterative FGI method to achieve a GI of a grayscale object.Without adding the complexity of the imaging system,this new approach can not only maintain a high resolution and visibility,but also improve the SNRs to a certain extent,especially for complex grayscale target objects the effect is more obvious.After further study,it is also found that the band-pass FGI can reduce the influence of distance on the resolution of the system.When the resolution value of traditional GI increases rapidly with the increasing of imaging distance,the resolutionvalue of band-pass FGI can still increase slowly between one and two pixels.At the same time,the relationship between resolution,visibility,SNRs,threshold,bandwidth and iterative number will be discussed in detail.