光子筛光学特性分析及应用研究

发布时间：2018-03-20 04:03

本文选题：光子筛　切入点：像差计算　出处：《中国科学院光电技术研究所》2017年博士论文　论文类型：学位论文

【摘要】：X射线和极紫外波段在光刻、空间望远镜、X射线光谱检测和高分辨率显微镜等领域有不可替代的作用。但是在X射线和极紫外波段大多数传统的光学材料的折射率接近或者小于1,不能作为透镜来聚焦和成像。波带片通过相位调制来实现聚焦,不受波长的限制,是X射线和极紫外波段的重要衍射透镜。波带片的分辨率受限于其最外环的尺寸,为了寻求更高的分辨率,2001年德国科学家L.Kipp等人首次提出使用光子筛来代替波带片。结构上光子筛采用大量的微孔代替菲涅尔波带片的环带结构,相对于波带片具有以下优点:首先,在相同的特征尺寸条件下,具备更大数值孔径,实现更高分辨力,而且小孔衍射可以抑制部分高阶衍射,压低聚焦光斑的旁瓣;其次,光子筛的微孔分布没有打断结构的连续性,不需要额外的衬底作为支撑,可以制作为薄膜光学元件,具有大口径,质量轻,体积小等优点;再者,光子筛小孔排布为设计提供了更多的可能性,可以通过改进光子筛设计达到优化聚焦成像以及实现特殊光场分布等目的。本文针对光子筛成像和聚焦两大问题,开展光学性能分析和应用研究。在光子筛聚焦方面,之前的国内外学者主要将精力集中在光子筛聚焦性能的改进,比如分辨率,衍射效率和焦深等,对光子筛聚焦时多焦点的现象研究不足。本文研究了光子筛多焦点机理,将光子筛和伽伯波带片结合,设计了单焦点光子筛,并进行了模拟仿真和实验验证,证明单焦点光子筛可以减弱聚焦时的背景光,提高图像的信噪比。并利用光子筛微孔排布的自由度,设计了交错式光子筛,简单的改变光子筛环带,利用光子筛聚焦来实现局域空心光束,光场计算和实验证明了其可行性,并可以产生极小尺寸的空心光斑,该结构在光镊、粒子约束和原子冷却中具有重要应用。光子筛作为成像元件在现实中的应用需求越来越迫切,而光子筛像差问题一直没有引起足够的重视,为此,本论探究了光子筛像差计算方法,建立了光子筛等效波像差模型,突破了以往光斑尺寸的评价指标,拓展了光子筛的光学分析内涵。并具体进行了光子筛像差实例计算,总结光子筛像差特点,并研究了像差影响因素。在成像应用方面,设计了三平面和九平面同时成像光子筛,建立了三维成像光子筛的成像模型,模拟了其点扩散函数,并实验证明了可行性,三维成像光子筛有望在X射线显微成像发挥重要用途。此外,提出了基于光子筛的光谱成像方法,对光子筛光谱成像原理和成像模型进行了细致的分析,研究了光谱数据重建算法并进行模拟仿真。总之,本论文完善了光子筛的光学特性的分析,并在聚焦和成像方面开展了诸多卓有成效的应用研究,为光子筛广泛应用奠定了基础。
[Abstract]:X-rays and extreme ultraviolet bands in photolithography, Space telescope X-ray spectroscopy and high resolution microscopy have irreplaceable effects. However, the refractive index of most traditional optical materials in X-ray and extreme ultraviolet bands is close to or less than 1, and cannot be considered as transparent. The waveband plate is focused by phase modulation. Independent of wavelength, they are important diffraction lenses for X-ray and extreme ultraviolet wavelengths. The resolution of the band plate is limited by the size of its outermost ring, In 2001, in order to seek higher resolution, German scientist L. Kipp and others first proposed the use of photonic sieve instead of the band plate. The photonic sieve in the structure uses a large number of micropores to replace the annular structure of the Fresnel band plate. Compared with Yu Bo strip, it has the following advantages: firstly, it has larger numerical aperture and higher resolution under the same characteristic size, and small hole diffraction can suppress some higher-order diffraction and suppress the sidelobe of focusing spot. The micropore distribution of the photonic sieve does not break the continuity of the structure, does not need additional substrate as the support, can be made into thin film optical elements, with the advantages of large aperture, light weight, small volume and so on. The arrangement of photonic sieve holes provides more possibilities for the design, which can optimize the focus imaging and realize the special light field distribution by improving the photonic screen design. In this paper, we aim at two major problems: photon screen imaging and focusing. In the field of photon screen focusing, previous scholars at home and abroad have focused on improving the focusing performance of the photon screen, such as resolution, diffraction efficiency and depth of focus, etc. The multi-focus mechanism of photonic screen is studied in this paper. The single focus photonic screen is designed by combining the photon screen with the gamma wave band plate, and the simulation and experiment are carried out. It is proved that the single focus photon screen can weaken the background light and improve the signal-to-noise ratio of the image. The local hollow beam is realized by photon sieve focusing. The optical field calculation and experiment prove its feasibility, and it can produce very small hollow spot. The structure is used in optical tweezers. Particle confinement and atomic cooling have important applications. The application of photonic screen as imaging element is more and more urgent, but the problem of photonic screen aberration has not been paid enough attention to. This paper probes into the calculation method of photonic screen aberration, establishes the equivalent wave aberration model of photonic screen, breaks through the previous evaluation index of light spot size, expands the connotation of optical analysis of photonic screen, and makes a practical calculation of photon screen aberration. The characteristics of photonic screen aberration are summarized, and the influence factors of aberration are studied. In imaging application, the imaging model of 3D imaging photonic screen is established and its point diffusion function is simulated. The experimental results show that the three-dimensional imaging photonic screen is expected to play an important role in X-ray microscopic imaging. In addition, a spectral imaging method based on photonic screen is proposed, and the principle and model of photonic screen spectral imaging are analyzed in detail. The spectral data reconstruction algorithm is studied and simulated. In a word, the optical properties of the photonic sieve are analyzed, and a lot of fruitful application researches have been carried out in the field of focusing and imaging. It lays a foundation for the wide application of photon screen.
【学位授予单位】：中国科学院光电技术研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O43

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