| The mid-infrared laser has very important value and broad application prospects in many fields such as laser communication,remote sensing,spectral analysis,military medical,because of its strong penetrating power through atmosphere and its special wavelength band which covers many absorption peaks of atoms and molecules.In this paper,systematic analysis and experimental verification is carried out to resolve some key problems,which includes phase distortion detection problem throughout the whole-journey transmission and its adaptive optics correction.The so-called whole-journey transmission can be divided into three sections based on the direction and path of beams,namely source section,internal channel transmission section and outer atmospheric transmission section,and the optical aberration of these sections is discussed in the paper.The emphasis is,(1)The temporal and spatial characteristics of mid-infrared laser transmission aberration and the impact of high frequency components on transmission efficiency are quantitatively analyzed,and finally,mid-infrared laser transmit as a near diffraction limit beam in the experiment designed on this basis.(2)The aberration characteristics of beam splitter mirror is established based on geometrical optics theory of transmission and reflection deformation aberration,which provides the theory basis for dynamic correction for the aberration of beam splitter mirror in traditional adaptive optics.On the content of the mid-infrared laser beam control in the whole-journey transmission,this paper is divided into two parts,model adaptive correction,direction control,as well as the research of beacon mechanism for infrared laser system.(1)The physical mechanism and applicable condition of phase conjugate compensation is discussed,and the conclusion shows that the larger compensation wave aberration,the smaller Fresnel number,the greater affect of reciprocity problems,if we focus on the reciprocity problems caused by "beacon detection-wavefront compensation-main laser transmission" work system.(2)And then,correction dead zone in traditional structure and working principle of CP/CM technology is further clarified,through the discussion of theoretical errors between the traditional adaptive optics and common path/common mode adaptive optics(CP/CM)under different calibration zero points.At last,a lot of design scheme are experimental studied and verified.(3)Comprehensive analysis of three beacon lighting system among rayleigh beacon,sodium beacon and illumination beacon shows that the last one is the most suitable beacon mechanism for mid-infrared laser system.And theoretical analysis and experimental verification also shows that the application of incoherent beam array system can obviously improve target illumination uniformity,reducing the influence of the scintillation effect.Finally,the modifying factors of angular anisoplanatism are acquired through numerical simulation,and the conclusion that the effect of angular anisoplanatism is not as serious as in the traditional understanding is also verified by experiment results.(4)For the whole-journey beam direction control technology,this paper focuses on two problems including the influence to beam tilting detection by back diffraction light field of pyramid prism array and the influence to high precision optical axis calibration by nearly horizontal chromatic aberration of the atmospheric refraction.The study results shows that the wavefront sensor will have significant errors in the measurement of the inclined wavefront if considered corner pyramid array diffraction and the wavefront sensor shrinkage ratio is deviated by 2%.It's necessary to select the experimental time carefully when calibrating high-precision optical axis in order to improve calibration accuracy.Normally,the deflection angle error caused by the near-ground chromatic aberration of the atmospheric refraction will not exceed 0.25 ?rad,before or after the evening transition time. |
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