基于角谱传播的钠信标光斑形态分析  

Spot Profile Study of Sodium Beacon Based on Angular Spectrum Propagation

作　　者：黄建 邓可然 李祝强 HUANG Jian;DENG Keran;LI Zhuqiang(Chongqing Key Laboratory of Green Design and Manufacturing of Intelligent Equipment,School of Mechanical Engineering,Chongqing Technology and Business University,Chongqing 400067,China;College of Physics and Electronic Engineering,Chongqing Normal University,Chongqing 401331,China)

机构地区：[1]重庆工商大学机械工程学院智能装备绿色设计与制造重庆市重点实验室,重庆400067 [2]重庆师范大学物理与电子工程学院,重庆401331

出　　处：《光子学报》2025年第2期252-266,共15页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.62105047,62305038);中国博士后科学基金(No.2021M703593);重庆市自然科学基金(No.CSTB2024NSCQ-MSX0698);重庆市博士后研究项目特别资助(No.2023CQBSHTB3135);重庆市教委科技项目(No.KJQN202200567)。

摘　　要：钠信标光斑形态是影响钠信标自适应光学系统波前探测精度的关键因素,主要由钠层激光功率密度分布和回光效率决定。为准确估计钠信标光斑形态,利用角谱传播理论,建立了钠激光在连续非均匀大气介质中的传输模型,得到钠层激光功率密度分布。根据回光效率与功率密度的关系,得到不同湍流强度(r_(0)为5~30 cm@550 nm)下钠信标的光斑尺寸位于0.26 m到0.22 m之间,回波光子数位于(1.3~1.4)×10^(7)photons·s^(-1)·m^(-2),并讨论了不同大气分层数量,对钠信标光斑形态的影响。利用质心提取算法,对钠信标光斑形态质心进行提取,讨论了不同强度大气湍流倾斜像差对钠信标指向位置的偏移,其偏移最大值约为60 cm。最后,分析了不同情况下的钠信标光斑闪烁效应,随着分层数量增加,衍射效应将减弱闪烁饱和效应。Adaptive Optics(AO)plays a key role in large-aperture ground-based telescopes,which corrected the wavefront distortions of atmospheric turbulence,and a diffraction image can be obtained.The first step for working AO is the phase aberrations sensed by a Wavefront Sensor(WFS)with a bright beacon adjacent to the science object.Unfortunately,the natural beacon is not populated with sufficient number in the sky,while the Rayleigh beacon is generated near 10 km with a significant cone effect.The sodium beacon was generated by the sodium atoms at 90 km excited with a laser tuned to D2 line,which can probe the turbulence along the cylinder path more completely.Thus,the sodium beacon becomes an essential facility for 10 m class telescopes and the next-generation telescopes.The accuracy of the Shack-Harmann WFS is severely affected by the sodium beacon spot profile.The more compact the spot size and the greater the flux of photon return,the better the measurement accuracy.So,it is essential to estimate the sodium beacon spot profile during the AO system's design phase.The spot profile is determined by the power density at the sodium layer and the photon return efficiency of the laser interaction with the sodium atoms.The power density distribution at the sodium layer is spread by many factors,such as the diameters of the Laser Launch Telescope(LLT),the beam quality of the laser,the turbulence along the uplink path,the static aberrations in the laser launch optical path and so forth.Most of the factors can be optimized in the design of the laser launch system.Thus,the turbulence along the uplink path is a critical factor that should be considered.In this paper,the analyzation was based on the second generation LLT at Gaomeigu Lijiang astronomy observatory with a diameter of 300 mm,the laser is a Quasi-continuous Wave(QCW)solid state sodium laser with a power of 20 W,fabricated by the Technical Institute of Physics and Chemistry(TIPC),the atmospheric turbulence(value of Fried parameter r_(0)at 550 nm)varies from 5 cm to 30 c

关 键 词：钠信标 角谱传播 光斑形态 指向位置 闪烁 

分 类 号：P427.1[天文地球—大气科学及气象学]