| In recent years,as an emerging non-local imaging technology,correlation imaging has attracted more and more attention from domestic and foreign scholars due to its outstanding advantages such as strong anti-interference and high resolution.Correlation imaging has wide application prospects in many fields such as military,astronomy,and medicine.For example,in the field of remote sensing imaging,correlation imaging can use thermal photon fluctuations to obtain images of distant objects;in the field of biomedical imaging,due to the correlation The anti-interference properties of imaging and good imaging capabilities in scattering media make it possible to recover information from biological tissues and turbid liquids.In the development and practical application of related imaging technology,how to continuously improve the imaging speed and imaging quality has always been an important issue that researchers have paid attention to and studied.When light propagates in the air,the interference of the presence of atmospheric turbulence on the imaging process associated with imaging is one of the factors that affect the imaging quality.Therefore,the influence of atmospheric turbulence on imaging has received more attention and research since the emergence of correlation imaging.Theoretically,the transmission mode in the correlation imaging system is divided into horizontal and slope.The atmospheric structure constant during horizontal transmission can generally take a fixed value,while the atmospheric structure constant during inclined transmission is not only disturbed by random factors such as wind speed and air pressure.It will continue to change with changes in altitude,and at the same time,the zenith angle also affects the beam transmission.Therefore,compared with correlation imaging in horizontal atmospheric turbulence,research on correlation imaging in oblique range atmospheric turbulence is relatively complicated.This paper mainly studies the correlation imaging through turbulent atmosphere along a slant path.The main contents are as follows:1.Based on the generalized Huygens-Fresnel principle,using the modified von Karmon spectrum model and the atmospheric refractive index structure constant model issued by ITU-R,the correlation function and resolution analysis of the correlation imaging of the upward transmission calculation in the oblique atmospheric turbulence are derived formula.According to the analytical results,for the parameters of near-surface turbulence intensity,zenith angle,transmission distance,and light source size,numerical simulations were performed to simulate the changes in the imaging resolution associated with the upward transmission in the oblique atmospheric turbulence at different internal and external turbulence scales.According to the simulation results,the effects of internal and external turbulence scales on computational correlation imaging in oblique atmospheric turbulence are compared and analyzed.The results show that the internal scale of turbulence has a significant effect on the resolution of the computed correlation imaging in oblique atmospheric turbulence,while the external scale of turbulence has little effect on it.2.Based on the generalized Huygens-Fresnel principle,using the Tatarskii spectral model and the atmospheric refractive index structure constant model promulgated by ITU-R,the correlation function and resolution analysis of the correlation imaging of the upward and downward transmission calculations in the oblique atmospheric turbulence are derived formula.According to the analytical results,for the parameters of turbulent internal scale,zenith angle,near-surface turbulence intensity,transmission distance and light source size,the changes in the associated imaging resolution during atmospheric upward and downward transmission in atmospheric turbulence are numerically simulated.Based on the simulation results,the effects of different transmission methods of upward and downward transmission on the correlation imaging in oblique atmospheric turbulence are compared and studied.The results show that when the parameters of turbulent internal scale,zenith angle,near-surface turbulence intensity,transmission distance and light source size change,the correlation imaging resolution during downward transmission in oblique atmospheric turbulence is significantly higher than the imaging resolution during upward transmission rate. |
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