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题名	大口径宽波段高能激光发射窗口研究
作者	刘旭堂
学位类别	博士
答辩日期	2015-05
授予单位	中国科学院大学
导师	高云国
关键词	激光发射系统 激光发射窗口 快门窗口 大口径 宽波段
其他题名	Research on Large-diameter Multi-band High-energy Laser Emission Window
学位专业	机械制造及其自动化
中文摘要	窗口是激光发射系统的重要组成部件，主要用于保护系统内部光学元件，提高设备的环境适应能力。目前激光发射系统使用的窗口分为晶体窗口和气动窗口两种。现代激光发射系统的孔径越来越大，晶体窗口受到晶体尺寸的限制，气动窗口消耗大量能源，两者均不能满足大口径高能激光发射系统的使用要求。目前国内外关于大口径宽波段高能激光发射系统所使用窗口的研究暂无报道，国内工程上500mm以上口径的激光发射系统也处于无窗口状态，严重制约了系统在复杂环境中的使用。为此本文首次提出了一套气动窗口与机械式快门窗口相结合的密封方法，并设计相应的快门窗口。针对大口径宽波段高能激光发射系统的使用要求设计拼接式晶体窗口。 拼接窗口结构设计：首次提出以镜片拼接的方式来设计大口径激光发射窗口。从工程应用角度分析了窗口的设计要求、加工精度和安装精度对出射激光的影响，依据几何光学和激光光学的相关知识建立相应的评估模型，并以该模型为基础优化拼接窗口的结构。 拼接窗口强度计算：分析激光发射和各种环境因素对拼接窗口的影响，并结合断裂力学和材料力学的相关知识建立评估模型。根据拼接窗口的强度、刚度和动力学特性优化拼接窗口的结构，为窗口的径向支撑机构设计了柔性铰链，并推导出了柔性铰链弯曲刚度的力学模型。 光束质量分析：采用有限元方法求解窗口的温度场和应力场，基于热固耦合法分析窗口的面形畸变，利用齐次坐标变换分离刚体位移，利用zernike多项式拟合窗口面形，通过分析激光远场光强的变化来计算拼接窗口对发射激光的影响。经过计算分析发现：拼接窗口对出射激光衍射极限倍率、环围能量比和斯特列尔比的影响小于5%，对激光发散角的影响小于0.1〞,与单片晶体制造的窗口相比，拼接窗口的晶体质量降低60%。 快门窗口的设计：针对激光发射系统的工作特点，首次提出了气动窗口与快门式机械窗口相结合的密封方法，依据窗口的设计要求确定窗口的结构形式，依据各传动环节的受力条件和窗口的抗风载能力模型优化窗口的尺寸。 快门窗口的理论分析：基于柔索力学和微积分原理建立无弯曲刚度防尘罩的风载模型；基于薄板大挠度变形理论和薄膜力学建立有弯曲刚度防尘罩的风载模型；两个数学模型分别满足不同类型的激光发射窗口的设计要求。借助机械动力学和有限元法求解窗口的动力学特性。 实验：通过测试快门窗口的抗风载能力、动力学特性和环境温度的适应性，验证了理论分析的准确性。工程实践证明：本文所推导风载模型的计算误差小于15%，机械窗口可以抵御8级以下风砂的侵袭，可以在-40℃至60℃的环境温度范围内正常使用，气动窗口与机械窗口相结合的密封方法可以有效提高设备的环境适应能力。
英文摘要	As an important component of a laser emission system window can be used to protect the components within the system and to improve the adaptive capacity to environment. Art-of-the-state laser emission systems use two kinds of windows are respectively crystal windows and pneumatic windows. However, the modern laser emission system apertures become larger and larger such that crystal windows have a limitation in crystal dimensions while pneumatic windows consume lots of energy. Both of these two sorts of windows cannot satisfy the working requirements in large-diameter high-energy laser emission systems. It is rarely reported in domestic in large-diameter multi-band high-energy laser emission systems while in engineering areas the laser emission systems with diameters of more than 500 mm are still owning no windows resulting in less use of laser emission systems in extreme environments. In this context this thesis proposes a combined seal method of pneumatic window with mechanical shutter window and puts forward the design of the associated shutter window. To meet the working requirements we also design the stitching crystal window for the large-diameter multi-band high-energy laser emission system. Structural design of stitching window: we first time propose a mirror stitching method to design the large-diameter laser emission window. In terms of engineering we analyze the efforts of design requirements, machining accuracy, and assembly accuracy on the emitted laser. According to the Geometrical Optics and Laser Optics we establish the relevant assessment model based on which the structure of stitching window is optimized. Strength calculation of stitching window: we analyze the efforts of laser emitting and different settings on the stitching window. By combining the Fracture Mechanics with Mechanics of Materials, an assessment model is built up. The window is also optimized directly on the basis of strength, stiffness and dynamical properties. We also design the flexible hinges for the window’s radial supporting mechanism and derive out the mechanical model of flexible hinge bending stiffness. Beam quality analysis: We apply the finite element method to solve the temperature field and strain field for the window. Using the thermal-mechanical coupling method calculates the surface distortion of the window and using homogeneous transformation separates the stiff displacements. Subsequently, by adopting Zernike polynomials we fit the surface of the window and calculate the effort of stitching window on emitted laser by analyzing the variations of laser far-field intensity. Via the observations the efforts of stitching window on diffraction limit rate, encircling ratio and Strell ratio are less than 5% while on laser divergence angle are less than 0.1’’. The crystal mass is reduced by 60% compared with that of the single-mirror window. The design of shutter window: We first time propose a combined seal method of pneumatic window with mechanical shutter window in terms of laser emission system characteristics. The structure is typically designed by the requirements. The dimensions of window can be optimized naturally by load conditions of transmission links and the wind-resisting model of relevance. Theoretical work of shutter window: We establish the wind load model for bending stiffness-free dust cover by using the rope mechanics and similarly establish the wind load model for bending stiffness dust cover by using the shell large deformation theory and film mechanics. These two mathematical models have been respectively shown that they can satisfy different laser emission window. With the use of the mechanical dynamics and finite element method we calculate the dynamical properties. Experiments: Experiments: Through testing the wind-resisting abilities, dynamical properties and adaptation in different environment temperatures of shutter window, we validate the theoretical analysis. The engineering practice also indicates that the calculation error of wind load model is less 15% and the mechanical window is capable of resisting the invasion of wind and dust that can be up to 8 magnitude. The window can be used normally in environmental temperature ranging from -40C-60C. Moreover, the combined seal method of pneumatic window with mechanical window can significantly and effectively improve the adaptive ability of facilities.
公开日期	2015-12-24
内容类型	学位论文
源URL	[http://ir.ciomp.ac.cn/handle/181722/48875]
专题	长春光学精密机械与物理研究所_中科院长春光机所知识产出
推荐引用方式 GB/T 7714	刘旭堂. 大口径宽波段高能激光发射窗口研究[D]. 中国科学院大学. 2015.

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