共查询到20条相似文献,搜索用时 61 毫秒
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作为强激光系统的终端组件之一,光束采样光栅是制作在熔石英基底上的浅槽光栅。利用熔石英的传统化学机械抛光技术,修正熔石英光束采样光栅的槽型轮廓,降低局部偏高的衍射效率,以提高光束采样光栅的整体效率均匀性。利用此方法已成功将430 mm430 mm的光束采样光栅的衍射效率均方根值(RMS)由30%附近降低到5%以下。实验结果显示,利用传统化学机械抛光技术可以有效提高光束采样光栅衍射效率均匀性,这是一种可行的技术方案。 相似文献
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详细研究了准分子激光光束均匀性的各项评价指标,加工窗口描述了加工任务本身对光束均匀度的要求;能量分数回答了具体加工窗口即均匀度要求下的能量利用率问题;平顶因子则描述了整个光斑能量分布范围内的均匀性问题。利用激光波面分析仪对不同均匀器所获得的均匀光束进行评价比较,蝇眼透镜均匀器能量利用率高,整个光斑内的均匀效果好,但最佳均匀截面的位置动态范围小;组合棱镜均匀器均匀截面动态范围大,但整体均匀效量较差。 相似文献
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讨论DF(氟化氘)强激光系统光束定向器中的光学薄膜,用偏振光线追迹分析定向器出瞳主激光、信标光偏振态变化,计算膜厚不均匀性对远场性能的影响. 相似文献
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非晶合金,即金属玻璃,是一类特殊的由基本化学元素组成的非晶态物质,由于其独特的微观组织结构,展现出了不同于传统晶态合金材料的特殊物性,而成为高性能材料应用领域的重要一员.由于非晶合金的结构无序性,且当前精确表征其微观结构的实验手段缺乏,相应的理论模型也不完善,人们对非晶合金中一些基础物理问题的认识尚且不足,无法形成基本的理论框架来精确地描述其物性产生的微观机理.因而,当前非晶合金研究的核心问题可以概括为:如何建立以微观特征或结构为基础的基本理论框架,准确地概括非晶合金物性的微观机理.在过去几十年里,针对非晶合金的大量研究表明,在非晶合金长程无序的特征中,隐藏着本征的不均匀性和有序,且这些不均匀性的特征与材料物性有着密切的关联,使得建立以不均匀性特征为基础的理论框架成为可能.本文从非晶合金微观特征的不均匀性包括静态不均匀性和动态不均匀性的视角出发,概括性地总结了非晶合金材料与物理研究中取得的丰硕成果,及当前需要关注的重要科学问题,并针对未来可能的研究模式进行了展望. 相似文献
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二极管激光器阵列端泵浦Nd:YAG板条具有热效应低、波前畸变小的特点,温度场和应力场的不均匀是引起板条增益介质波前畸变的主要原因。对端泵浦传导冷却Nd:YAG板条增益模块的泵浦和冷却均匀性进行了优化设计,获得了板条激光增益模块静态波前畸变最大偏差(PV)值为0.22 m。该模块用于双通放大器实验装置中,测试了板条增益模块有无注入功率条件下的波前畸变,测得无注入功率波前畸变PV值为3.49 m,能量提取后波前畸变PV值为3.41 m。在注入功率3120 W时,获得输出激光功率4660 W,光束质量为3.88倍衍射极限,该模块光光效率为27%。 相似文献
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Xiaojin Yang 《中国物理 B》2022,31(7):74202-074202
The reflection and transmission of a finite-power Airy beam incident on a dielectric slab are investigated by an analytical method. Based on the plane-wave angular spectrum expansion and Fresnel approximation, the analytical expressions of the reflected field, internal field as well as transmitted field in each region are obtained. Through numerical simulations, the intensity distributions of the incident beam, reflected beam, internal beam as well as transmitted beam are presented at oblique incidence. Besides, we also compare the intensity distributions of the geometrical-optics beam field, the first order beam mode field and the actual beam field, which indicates that the contribution of each order beam mode field to the actual beam field is related to the refractive index of the dielectric slab. Meanwhile, the reflection characteristics of the Airy beams in the special cases of Brewster incidence and total reflection are investigated. Finally, the effects of the optical thickness and refractive index of the dielectric slab on the peak intensity distributions and beam shifts of the reflected and transmitted beams are also discussed in detail. The analytical and numerical results will be useful to analyze the propagation dynamics of Airy beam in the dielectric slab and provide some theoretical supports to the design of optical film. 相似文献
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A general theory of the two-beam coupling between a pump beam and a signal beam in photorefractive materials is presented. The coupled wave equations describing the non-linear two beam coupling are derived, based on Maxwell's wave equation. The coupled equation for the intensities of the two beams in the photorefractive crystals with the absorbing properties have been derived analytically. The intensity of the signal beam increases with the increasing crystal thickness, reaches a maximum and then decreases. The influence of energy beam coupling coefficient, oscillation frequency shift, crystal thickness, absorption coefficient and the input beam intensity ratio on the signal beam intensity have been studied in details. The effect of the photoconductivity of the materials on the intensities of the two beams in both the co-directional as well as contra-directional two beam coupling cases have been studied. 相似文献
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To increase the quantum efficiency (QE) of a copper photocathode and reduce the thermal emittance of an electron beam, a drive laser with oblique incidence was adopted in a BNL type photocathode rf gun. The disadvantageous effects on the beam quality caused by oblique incidence were analyzed qualitatively. A simple way to solve the problems through wavefront shaping was introduced and the beam quality was improved. 相似文献
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针对高功率固体激光驱动器的安全运行,提出了覆盖驱动器建设全过程的污染控制方法,详细介绍了洁净清洗、洁净检测、洁净保护等保障污染控制效果的技术手段,并介绍了神光-Ⅲ主机装置片状放大器洁净度提升所采取的技术途径,以及片状放大器光照清洗实验中气溶胶等级随闪光灯照射次数的变化情况。实验结果表明,神光-Ⅲ主机装置的洁净水平与美国国家点火装置(NIF)接近且优于其他同类装置,洁净度的大幅提升为装置的安全运行提供了有力保障。 相似文献
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A new waveguiding structure based on NRD (Nonradiative Dielectric) guide with a double-layer LHM (Left Hand Material) slab
is carefully investigated. Rigorous multi-mode network treatment combining with mode matching method is carried out to analyze
the propagation characteristics of the structure. Theoretical analysis results reveal that depending on the choice of permittivity
and permeability of the two dielectric slabs, the guiding structure is of series distinct and interesting properties, such
as anomalous dispersion, opposite polarization modes coupling, and the existence of complex mode. Besides, the new configuration
can also be used as a leaky wave antenna working in the dominant or the first higher order mode. All these particular features
create various applications in electromagnetic engineering. 相似文献
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Mingyi Sun 《International Journal of Infrared and Millimeter Waves》1997,18(9):1725-1729
In this paper three-dimentional simulations are carried out to the phase velocity of a transverse electric wave which propagates
in a relativistic electron beam magnetized by a wiggler field and an axial guide magnetic field. Results show that the phase
velocities are quite different from each other as the axial guide magnetic field changes its direction. 相似文献