Analysis Of The Influence Of Estimation Error Of Statistic Transfer Function On Reconstruction Results Of NVST High Resolution Algorithm

As China's largest ground-based solar telescope,the 1 m New Vacuum Solar Telescope(NVST)has the mission of providing high-quality,high-resolution observation data to solar physics researchers.Estimating the statistical transfer function precisely,is a key step in the reconstruction of the NVST image,but some factors such as telescope aberration,photon noise,and anisoplanatism effect can make some deviation in the process of the estimation of transfer function.In the data processing of high resolution solar data,the estimation error of the statistical transfer function will result in the resolution of the high resolution data being reduced or even distorted.Therefore,it is necessary to study the influence of the statistical transfer function's estimation error on the high resolution image reconstruction algorithm,which will get better resolution of the reconstructed image.Based on the theory of speckle reconstruction algorithm,the influence of aberration,noise and anisoplanatism effect on the reconstruction of NVST high resolution algorithm is studied by theoretical derivation,numerical simulation and reconstruction of observed photosphere data.The main consideration is as follows:1.The influence of estimation error on the reconstruction of object's Fourier mode;2.The influence of estimation error on the reconstruction of object's Fourier phase.The main work of this thesis is as follows:1)In the same seeing,the influence of different aberrations of the same typeaberration on the high resolution reconstruction of NVST is analyzed and theinfluence of the same aberration of different types of aberration on the results ofhigh resolution reconstruction of NVST is analyzed.In different seeing,Theinfluence of the same aberration size on the high resolution reconstruction ofNVST is analyzed.2)The influence of photon noise on the reconstruction of image power spectrum isanalyzed.The influence of different photon noise on the spectral ratio curveunder different seeing is analyzed.In different seeing,the influence of differentphoton noise on the reconstruction of NVST algorithm.3)The influence of anisoplanatism on the Speckle Interferometry Transfer Function,Speckle Masking and spectral ratio method are deduced.The anisoplanatismeffect on the reconstruction of NVST high resolution images is analyzed by usingthe average power spectrum.When the aberration does not exceed a certain range,the aberration does not have much impact on the reconstruction results.When the aberration number exceeds a certain range,the aberration will affect the reconstruction results and this effect will be more obvious with the increase in aberration and the increasing of seeing constant.The effect of defocus aberration and spherical aberration on image reconstruction is relatively severe.Photon noise lead some bias in the speckle power spectrum and there will be a high-frequency amplification phenomenon in the reconstruction,that leading to the high-frequency information we want to rebuild cannot be restored effectively.In good seeing,the influence of photon noise on the spectral ratio curve is larger than poor seeing,which will make errors in our estimation of the transfer function.The photon noise will significantly reduce the reconstruction accuracy of the recursive phase of the bispectrum when seeing is generally poor.Anisoplanatism has an effect on the reconstruction of a large extended source,which will result in the inaccurate reconstruction of speckle interferometry and cause the image resolution to decrease.In order to obtain better resolution in the reconstructed image,it is best to restricting the size of the reconstructed field to an area smaller than the isoplanatic path.So that the effect of anisoplanatism effect is minimal,or even negligible.