| 题名 | 星间激光通信中大型光学主镜的有限元分析验证 |
| 作者 | 张德江 |
| 学位类别 | 硕士 |
| 答辩日期 | 2005 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 刘立人 |
| 关键词 | 星间激光通信 平行光管 卫星相对轨道模拟器 有限元分析 |
| 其他题名 | Finite element analysis and validation of large-sized optical primary mirror for inter-satellite Laser Communications |
| 中文摘要 | 卫星通信作为现代通信网中的一个重要环节，目前的微波卫星通信已经不能满足人们日益增长的通讯需求，星间激光通信相对传统的微波卫星通信有着巨大的优势和广阔的发展前景，世界上许多国家都开始了星间激光通信技术的研究。星间激光通信系统利用激光作为信息载体以实现卫星间的通讯联络，激光通信终端为其最为关键的部件，由于激光通信终端在发射之前必须在地面实验室内对其跟瞄参数和综合性能进行充分的验证与评估，因此作为对星间激光通信的一种支持单元技术，研究星间激光通信的地面检测技术也愈显重要。其中一项重要的工作是在地面模拟激光远距离传输的光场特性，需要用大口径、长焦距的平行光管来实现，要求平行光管在实现激光远场特性模拟的过程中，引起的波像差小于瑞利判据，再加上透镜加工制造，安装等引起的面形误差，平行光管引起的波像差要远小于瑞利判据刁能满足实验要求。因此，在实验室条件下研究大口径光学镜子由于自身的变形对系统光学性能造成的影响是一项重要的任务。实现星间激光通信的地面模拟检测另一个关键设备是轨道模拟装置。虽然曾有文献上提到对轨道模拟装置的相关研究与某些应用，但都只限于其功能的大致描述，实际并没有一个已经建成、普遍适用并可用于不同激光通信终端验证的卫星轨道模拟装置。本文介绍了我们课题组结合课题需要而设计的一种新型轨道模拟装置，该装置光学主镜由两个大口径圆形棱镜组成，安装在圆形钢筒内，根据实验要求，要保证棱镜顶角a为"，通光孔径中425mm。在这样的前提下，造成棱镜长、短边尺寸差距很大，棱镜单件质量可达36．625kg，这样的设计是否安全合理，棱镜的材料能否承受装卡状态下的最大应力，是我们关心的焦点，所以必须对棱镜在重力作用下的变形、应力及变形对装置光学性能的影响进行分析。对于以上情况的分析验证，有限单元法（FiniteElementMethod）不失为一种好的分析方法。本论文主要针对星间激光通信课题中大型光学主镜在重力作用下的变形及其对光学系统性能的影响进行研究，主要内容包括：1．从星间激光通信课题背景出发，讨论光学主镜面形变化的影响因素，阐明对其进行分析的必要性和重要性，提出有限元方法可很好的完成这一任务，对有限元分析方法在光学工程领域的应用作了较为详细的介绍，以及应用有限元分析软件ANSYS进行热弹性变形分析的典型步骤。2．在用大口径、长焦距平行光管模拟激光远场特性时，其光组透镜在重力作用下的变形不能忽略，为了分析透镜变形对出射光束质量的影响，采用有限元分析软件"ANSYS"建立了平行光管光组中必400mm平凸透镜的有限元模型，给出一种分析透镜轴向变形引起的波像差的方法，在不同工况下，计算了平凸透镜在重力作用下轴向变形的峰谷（P－V）值和均方根（RNIS）值，对轴向变形量RMS值最小工况画出了透镜表面变形的等值线图，计算了必350mm通光口径内的波像差P－v值和RMS值，对平行光管光组的波像差做出估计，远小于瑞利判据，验证了设计的合理性。3．对于旋转双棱镜轨道模拟装置，首先采用有限元方法分析了单棱镜在重力作用下三个典型位置的表面变形，对棱镜表面中425mm通光孔径轴向变形量进行Zernike多项式拟合，画出了相应的波差图，并确定设计方案。进一步选择小360mm口径光束对双棱镜在几种典型相对位置下进行光线采样、追迹，计算得到不同情况下由于双棱镜自重变形引起的总波差。本论文主要研究目的是对星间激光通信系统中大口径光学主镜的重力变形、应力以及对系统光学性能的影响进行分析，对于验证光学系统设计合理性、可靠性以及主镜的加工制造具有重要意义。 |
| 英文摘要 | Satellite communications is an important tache for modern communication network, now satellite microwave communications can't meet people the increasing need for communication, inter-satellite laser communications has large advantage and bright outlook in the future, many country carry out their research on inter-satellite laser communications. In the inter-satellite laser communications system, laser beam is used as the carrier of information to realize the communication among satellites, as a pivotal device, PAT(Pointing, Acquisition and Tracking) parameters and integrated technical specifications of laser communication terminals for inter-satellite link must be pre-verified and assessed thoroughly on a ground-based test-bed before launched into the space, to the aim, the research on ground-based simulative testing technology is very important. One of important work is to simulate the optical field character of laser far-distance transmission in space, it is usually simulated by a large-aperture and long-focus collimator, in the course of collimator simulate laser far-field character, when we consider the surface deformations induced by fabrication and mount of lens, wavefront error induced by collimator lenses must enough less than rayleigh condition, so the research on deformation of large-sized optical mirror and its effect to system optical performance is an important task. To realize on-ground simulation testing, another pivotal device is satellite relative-trajectory simulator. Through the comparison among the existing satellite trajectory simulation system for inter-satellite laser communications, we find that each one has some deficiencies in the practice, for example, high assemble cost, big volume and low efficiency, etc. In the paper, an original high-precision satellite relative-trajectory simulator designed by our group is introduced, it primarily include two large-aperture round prisms, to meet experiment request, apex angle of prisms must be 15°, and limiting aperture 425mm, so this lead to a result that the dimension difference of prisms long edge and short edge is big, and a prism mass is up to 36.625kg, in this case, our concern concentrate on that if this design is sound and if material can endure the maximum stress when prisms are mounted. So an analysis must be done about the deformation and stress of prisms and its effect to system optical performance. For the analysis and validation, finite element method is high-powered. The paper concern concentrates on the deformation of large-sized optical primary mirror induced by gravity and its effect to system optical performance, the details are listed in the following: 1. Based on the background of inter-satellite Laser Communications, the paper discussed the influencing factor leading to deformation of optical primary mirror, illuminated the necessity and significance to analyze it, and finite element method is used to finish the analysis task, the application of finite element method in optical engineering domain is introduced in detail, then the typical steps of finite element analysis are listed about finite element analysis software ANSYS. When a large-aperture and long-focus collimator is used to simulate laser far-fieldcharacter, the deformation of its lenses induced by gravity can't be ignored simply,to analyze the effect of lenses deformation to system optical performance, finiteelement analysis software ANSYS is used to simulate a 0400mm plane convexlens from a collimator, and a method is presented to analyze wavefront errorcaused by axial deformation of lens, P-V and RMS values of axial deformationsunder gravity are computed in different cases, the contours of lens surface areplotted when RMS axial deformations is the smallest, the P-V and RMSwavefront error in 0350mm are also calculated, finally the wavefront error oflenses is estimated in optimal case, the result is more less than rayleigh condition,the rationality of collimator design is validated. For double prisms of satellite relative-trajectory simulator, firstly finite elementmethod is adopted to analyze surface deformation of a single prism under gravitywhen it is in three typical positions, and Zernike polynomials are fitted for0425mm axial deformations of the prism surfaces, corresponding wavefront errorfigures are plotted, a design of prism is chosen from two. Then 0360mm lightbeam is sampled and ray tracing for double prisms in several typical relativeposition, and corresponding total wavefront error of double prisms under gravityare computed. The main aim of the paper is to analyze deformation and stress of large-sized optical primary mirror induced by gravity for inter-satellite laser communications system, and evaluates its effect to system optical performance, this has significance for rationality validation of optical system design and fabrication of primary mirror. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16538]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 张德江. 星间激光通信中大型光学主镜的有限元分析验证[D]. 中国科学院上海光学精密机械研究所. 2005. |
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