共查询到18条相似文献,搜索用时 671 毫秒
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衍射光学元件在无掩模光刻中的应用 总被引:3,自引:0,他引:3
描述了波带片/多孔透镜阵列无掩模光刻方法,着重介绍了波带片的几何结构特点和衍射聚焦特性,研究了影响光刻分辨率的因素和使用位相型波带片代替振幅型波带片提高衍射效率的设计方法,讨论了高级衍射焦点对波带片的光刻对比度的影响及消除措施,表明了波带片光刻有光刻对比度和高光刻分辨率受限于最小结构尺寸两个技术难点。对比介绍了多孔透镜的结构和衍射聚焦原理,论述了利用多孔透镜抑制高级衍射焦点和焦平面上次级大的特性,可以提高光刻对比度、提高光刻分辨率、克服波带片受限于最小结构尺寸的缺点。 相似文献
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用矢量Rayleigh-Sommerfeld(VRS)衍射理论分析计算了高数值孔径多台阶相幅型菲涅耳波带片(M-SHFZP)的聚焦场分布。当线性偏振光垂直入射到M-SHFZP,结果显示:1)由于薄膜透射率随着刻蚀台阶深度发生变化,致使实际的M-SHFZP的聚焦强度小于多台阶纯相位型菲涅耳波带片(M-SPFZP)的聚焦强度,但是M-SHFZP的聚焦光斑大小基本上与M-SPFZP的相同;2)聚焦光的强度随着台阶数的增加而增加,但聚焦光斑的大小不随台阶数变化;3)对于低数值孔径的M-SHFZP,光轴上的强度呈现一个多焦点分布,但是对于高数值孔径的M-SHFZP,高级焦点的强度被大大抑制。台阶数愈多,数值孔径愈大,抑制高级次焦点的能力愈强。VRS矢量衍射理论的计算结果与时域有限差分法(FDTD)模拟结果基本一致。 相似文献
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基于严格电磁场理论和结构拓展思想,提出了太赫兹缝隙结构衍射的严格物理模型,得到了太赫兹缝隙衍射情形下入射、衍射和透射区域内电磁场基本模式的严格表达。数值计算表明太赫兹波在晶体(砷化镓)、非金属(FR-4)等材料缝隙的透射系数与太赫兹波频率的变化趋势大体相似,得出缝隙材料对太赫兹波的透射系数影响不明显;但是,缝隙的个数、材料的种类以及基底材料的厚度对太赫兹缝隙衍射最大透射系数的影响明显。本文方法也可用于研究太赫兹波亚波长区域内、微纳光学元件体内衍射传输等问题。 相似文献
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给出了ZnTe电光晶体折射率和吸收系数随太赫兹波频率而变化的计算曲线,比较了太赫兹波在ZnTe中传播时的相速度和群速度。通过与太赫兹频率和晶体厚度相关的电光效率响应函数,理论计算了ZnTe电光晶体对太赫兹脉冲的探测电光响应,得到了晶体厚度与探测到的太赫兹频谱宽度的定性关系,从计算结果中找到了ZnTe电光晶体在5.3 THz和6.2 THz等多个频点的探测盲点,这些探测盲点来自于ZnTe电光晶体与相应频点太赫兹波的栅格共振吸收。结合自制的大口径太赫兹光导天线和1 kHz脉冲重复频率的太赫兹时域光谱实验系统,通过差分探测技术,从实验上得到了太赫兹波极化方向与〈110〉型ZnTe晶体晶轴方向的六个最佳匹配角度,给出了太赫兹电场最大值随晶轴与太赫兹波极化方向之间夹角变化的曲线及经验公式,这将有利于在实践中对该现象的深入理解和对探测灵敏度的有效提高。 相似文献
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为研究太赫兹波在沙尘暴中的传播特性,应用Mie散射理论研究了太赫兹波段沙尘粒子的散射特性,得到沙尘粒子的散射效率因子、消光效率因子和吸收效率因子随粒径、太赫兹波长的变化关系。基于沙尘粒子尺寸的对数正态分布,数值计算了沙尘暴的太赫兹衰减。研究结果表明,沙尘的衰减随能见度的增大而减小,波长越小,沙尘暴引起的太赫兹波衰减越大;波长为40 μm时,沙尘暴对太赫兹波传播影响最大,浮尘对太赫兹波传播影响最小。低能见度沙尘暴对太赫兹波传播影响明显。 相似文献
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在顺电相光折变晶体中存储全息相位光栅是研制新型电控全息光开关的有效途径。为了提高光栅的衍射效率,将Kogelnik耦合波理论与Kukhtarev方程相结合,得出了顺电相钽铌酸钾晶体中反射型相位栅衍射效率的解析式,对影响光栅衍射效率的各因素进行了计算分析。结果表明,使写入光的入射角远离45°、增加晶体厚度和增大外加电场等措施都可以使反射型全息相位栅的衍射效率提高。45°入射角附近出现较宽的低衍射区。衍射效率对入射角、晶体厚度以及外加电场的变化敏感,其中任一个参量的较小改变都可以引起衍射效率的较大变化。晶体的吸收对衍射效率的影响可以忽略。分析结果有助于在实践中调整参量以获得较高的读出光衍射效率。 相似文献
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Y. J. Guo S. K. Barton 《International Journal of Satellite Communications and Networking》1993,11(2):75-80
Owing to its flat nature and light weight etc., the Fresnel zone plate antenna is becoming very attractive for such applications as DBS reception and receive-only VSAT. The disadvantages of low efficiency and high sidelobes of the simple and the phase reversing zone plates can be improved by using phase correcting techniques. In this paper, a systematic investigation on the efficiency and sidelobe performance of subzone phase correcting zone plate antennas is presented. The design of a form of multilayer phase correcting zone plate reflector is described. A quarter-wave zone plate reflector constructed with three dielectric layers and metallized rings is reported, with measured peak efficiency of 55 per cent. 相似文献
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Diffraction of electromagnetic radiation remains a viable method for manipulation and focusing of extreme ultraviolet and X-ray wavelengths where the optical properties preclude significant phase shift without attenuation. As the wavelength becomes smaller, the characteristic dimensions needed for effective utilization of diffraction proportionally shrink, placing significant demands on the half-pitch of the diffractive structure. State-of-the-art nanofabrication technology is then required. Additionally, line placement over the entire grating, zone plate lens, or other diffractive element requires an accuracy on the order of a small fraction of a linewidth over the entire structure. This places a heavy burden on the alignment and calibration of the pattern-generating tool. In the case of zone plate lenses, smooth curved geometric elements are required. Specialized techniques for electron beam lithography have been developed to meet these demands, which diverge from the technology used to meet the challenges encountered in mask making and electronic circuit research. The techniques are in four areas: on axis calibration, beam placement, subpixel image processing for overlay, and smooth generation of arc shapes. Using the ensemble of these specialized techniques, high-resolution electron beam lithography nanofabrication has been used to successfully make diffractive structures with linewidths approaching 10 nm and near diffraction limited optical performance. 相似文献
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利用叠加所有圆环的解析近似衍射场的方法来计算和分析随机环带位置误差、宽度误差、扩散和粗糙度对X射线波带片的效率和分辨率的影响。用Strehl比来量化和衡量与理想波带片有偏差的波带片的性能,对两个波带片例子分别用Strehl极限确定了其能容许的四种误差极限。以一个Ni软X射线波带片为例,用叠加圆环衍射场的方法分析了随机环带位置误差和宽度误差对主焦点效率和分辨率的影响;以一个SiO2/Ni硬X射线溅射切片波带片为例,计算了两种材料的相互扩散和粗糙度对衍射效率和分辨率的影响。计算结果表明,四种误差越大,主焦点效率越小,分辨率越差,对第一个波带片例子而言,随机环带位置误差均方根和宽度误差均方根小于最外环宽度的30%;而对于第二个波带片例子,扩散区宽度和粗糙度均方根分别小于最外环宽度的105%和50%时,得到的Strehl比在Strehl极限之上。 相似文献
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将区板焦区场作为散射问题处理,得到区板感应面电流分布和焦区场分布后,本文利用场相关定理研究区板与馈源的耦合问题,并就主模激励下开口圆波导情形进行了计算和讨论。文中还采用矢量场绕射分析模型进行区板设计,给出了设计曲线 相似文献
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V. I. Balakshii A. V. Revenko 《Journal of Communications Technology and Electronics》2010,55(7):831-837
Light diffraction in a nonuniform acoustic field induced by a wedge-shaped piezoelectric transducer is theoretically studied.
Electric, acoustic, and acoustooptic characteristics of cells with such transducers are calculated. The emphasis is on the
features of cell operation in the case when a piezoelectric plate is excited at the third harmonic. The acoustic field is
shown to possess a complex amplitude and phase structure varying with the ultrasound frequency. The efficiency of acoustooptic
diffraction depending on the acoustic wave amplitude and phase mismatch is studied. It is established that the efficiency
of the Bragg diffraction can approach 100% despite a noticeable phase mismatch. Optimal values for the ultrasound power and
angles of light incidence onan acoustooptic cell are found. 相似文献
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