Noise And Resolution Analysis In Ghost Telescope Imaging System

Correlated imaging is called ghost imaging or coincidence imaging,which is started in entangled photon pairs from spontaneous parametric down-conversion.Later,the theoretical and experimental results show that the thermal light can be used to ghost imaging.As we know,the thermal light source is more readily available,and have the advantages of higher efficiency.As a new imaging technique,the specific advantages of ghost imaging mainly manifest in the realization of coherent imaging by using the non-coherent light source it also has an anti-interference characteristics of turbulence and so on.The noise is included in ghost imaging with thermal light,which will reduce the contrast of the image obtained,and it is not good for ghost imaging with complex objects.In this context,we mainly investigate the noise and the resolution in ghost telescope and Fourier telescope imaging system.Firstly,the mathematical expressions of the point spread function and the noise caused by the classical random fluctuation are derived by the second-order correlation functions in an f-2f imaging system.Large aperture,small source size and poor coherent are favorable for imaging resolution.While the large aperture,big source size and poor coherent are favorable for decreasing the noise.Thus,an appropriately large lens and the source with poor coherent are in favor of both the noise and the resolution.Secondly,we introduce the ghost telescope and ghost Fourier telescope imaging system on the basis of f-2f imaging system to study the noise and resolution,and replace the ordinary thermal light with the incoherent shaped light.Resolution will be improved with the increase of the modulation of the hyperbolic cosine-Gaussian source,and the noise increases with the increase of the modulation parameters of the cosine-Gaussian source for both ghost telescope and ghost Fourier telescope imaging system.One can obtain good resolution with small noise at the same time when the reference detector is located at its original plane.Finally,two kinds of high order shaped light are applied to ghost telescope imaging system,and we study their effects on the noise and resolution,and the visibility is also analyzed.The higher order the cosh-Gaussian light,the better the imaging resolution,and the noise has insignificant changes.Under high order cosine-Gaussian light,the imaging noise is slightly decreased in ghost imaging,but the imaging resolution is deteriorated in both ghost imaging and ghost Fourier-transform imaging.Therefore,the high-order cosh-Gaussian light can be used to improve the imaging quality of ghost Fourier-transform imaging.The results of numerical simulation show that when the cosine-Gaussian light is used in ghost telescope imaging system,the visibility firstly increases,then declines.While the effects of the cosh-Gaussian light on the visibility is completely contrary.In addition,for ghost telescope imaging system,the reference detector exists an optimal position,in which the good visibility and resolution,and the small noise can be obtained.