The Impact Of Wavefront Rotation And Polarization Chromatic Aberration On Correction Ability Of Adaptive Optical System

The adaptive optical system is an important means to correct the atmospheric turbulence in the laser transmission system,and a guarantee for the system to maintain an excellent working condition.But the adaptive optical system cannot correct the aberrations as expected at all rotation angles,when the ATP system of the laser transmission system rotates.The correction ability of the adaptive optical systems is declined when the system rotates in some directions.This thesis studies the reasons for the decline of the adaptive optical system's correction ability from the perspective of the wavefront rotation and the polarization chromatic aberrations generated by the optical thin films.In this thesis,the influence of relative rotation between incident wavefront and optical system on wavefront detection accuracy and wavefront reconstruction is analyzed.It is found that the effect of wavefront rotation gradually decreases to an acceptable range with the increase of the spatial resolution of the ShakeHartmann wavefront sensor and it has less effect on wavefront corrections.After this analysis,the focus of this thesis moves to the polarization chromatic aberrations between 1319 nm and 589 nm produced by optical thin films in Cassegrain beam expanding system and folding mirror.Then the influence of the polarization chromatic aberrations on adaptive optical system is analyzed.This paper mainly contains the following four parts:Firstly,the basic principle of wavefront detection in adaptive optical systems is introduced.Including the basic working principle of adaptive optics system,the working principle of Shark-Hartmann wavefront sensor and the basic principle of Zernike-mode wavefront reconstruction algorithm.Secondly,the polarization aberration theory is introduced in detail.At first,this thesis introduces the causes of polarization aberration of optical thin films,then describes the Pauli decomposition method of Jones Matrix and the second-order expansion equations of polarization aberration.Then the Singular Value Decomposition of Jones Matrix is introduced,which can decompose the Jones Pupil into five physical pupils and extract the wavefront produced by polarization aberration.This method is conducive to the subsequent wavefront analysis and make it easier to analyze the influence of the wavefront generated by polarization effect on adaptive optical system.Thirdly,the influence of wavefront rotation on wavefront detection is analyzed.By simulating Shake-Hartmann wavefront sensor to detect the rotating wavefront,the variations of the aberration components and the precision of the wavefront detection and wavefront reconstruction are analyzed,when the incident wavefront rotates.What's more,the influence of wavefront rotation on wavefront reconstruction accuracy with the spatial resolution of Shark-Hartmann wavefront sensor is analyzed.At last,the impact of wavefront rotation on system's correction ability is analyzed.Fourthly,the polarization chromatic aberrations produced by Cassegrain beam expanding system and folding mirror are analyzed.At first,the Jones Matrix are used to describe the impact of polarization aberration caused by optical thin films on amplitude and phase.Then the wavefront is extracted from the Jones Puli by Singular Value Decomposition.After that,a Shark-Hartmann wavefront detector is simulated to have an aberration analysis on this wavefront.On this basis,this thesis analyzes the polarization chromatic aberrations between 1319 nm and 589 nm produced by optical thin films in Cassegrain beam expanding system,as well as the decrease of the correction capability of adaptive optical system caused by polarization chromatic aberration.Then this thesis analyzes the relationship between the chromatic aberration and the F number of the optical system.After that,the polarization aberrations produced by folding mirror and the variation of wavefront aberrations with the divergence angle of the incident light are analyzed.Finally,by the way of experiment,the polarization aberration between the visible wavelength and 1319 nm due to the polarization effect of the complex optical films in plane mirror was measured.