Atmospheric Reconstruction By Lightfield Tomography

During the imaging of the target by the telescope,the refractive index of the air changes randomly due to the presence of atmospheric turbulence,which affects the imaging quality of the target on the imaging device.At present,adaptive optics is one of the most effective means to overcome the effects of atmospheric turbulence compensation,however,the traditional adaptive optics has challenges such as anisoplanatic error and small FOV(field of view).In order to solve these problems,researchers proposed to divide the atmospheric turbulence into several layers and place a deformable mirror at the conjugate position of each layer to correct the wavefront distortion caused by turbulence,and the way is called multi-conjugated adaptive optical technology.Atmospheric tomography restoration algorithm is the key and prerequisite for realizing MCAO technology and wavefront detector is also one of the most important components of adaptive optics system.As a new wavefront sensor device,the LightField Camera has the advantages of simple optical structure,high utilization of light energy and detection accuracy,and has received more and more attention from scholars at home and abroad.Due to its unique optical structure,the LightField Camera can obtain turbulent wavefront information in multiple line-of-sight directions through one exposure.A LightField Camera is expected to replace multiple wavefront detectors in the MCAO system to achieve multi-view atmospheric turbulence wavefront detection,and then to obtain different height atmospheric turbulence distribution through computational recovery.This technique is called LightField Tomography.This paper mainly studies the application foreground of the LightField Camera in wavefront detection and its important role in LightField Tomography.The main work in this paper is as follows:1.Review and introduce the development of adaptive optics technology,understand its main working system components,analyze the challenges and problems faced by wavefront detection methods at present,and combine the research background of wavefront detection based on LightField Camera at home and abroad.The application potential of the LightField Camera in the field of atmospheric tomography is proposed.2.Introduce the theoretical basis of wavefront detection technology for LightField Camera from two directions of geometric optics and wave optics,the mathematic physical model and numerical simulation system of the wavefront detection structure of the LightField Camera were established by MATLAB.In the case of single-angle/multi-perspective restoration of the LightField Camera,the numerical simulations of the single-order/complex order Zernike wavefront are performed.The simulation results show that the LightField Camera is feasible for wavefront detection.3.The atmospheric recovery algorithm of LightField Tomography is deduced and verified,and the mode coupling and mode confusion error existing in the algorithm are analyzed.A theoretical model of the LightField Tomography has been established.Using a LightField Camera wavefront detection structure to replace multiple wavefront detectors in the MCAO,and then detecting the cumulative wavefronts of the atmospheric turbulence at different heights in different viewing angles,we can reconstruct the wavefronts on different heights by using the LightField Tomography algorithm,and the precision has reached the expected result.