光学超分辨平面超构透镜研究进展

从光学自身机理上突破光学理论分辨率极限,实现远场超分辨光学点扩散函数,进而实现超分辨聚焦和超分辨成像,在激光加工、超分辨光学显微和超分辨望远等系统有着重要应用前景.近年来,光学超构表面的发展使得在亚波长尺度上实现光场振幅、相位及偏振的独立调控成为可能,为研制新型的超分辨平面超构透镜提供了更加灵活的手段.本文介绍了基于光学超构表面的超分辨平面超构透镜、相关测试技术方面几年来的研究进展,并讨论了该领域面临的问题和未来的研究重点和方向.     

用于纳米光刻的超分辨缩小成像平板超透镜研究

本文提出和研究了利用超分辨缩小成像平板超透镜,在i线光源波长下实现纳米尺度光刻方法.为了在超 分辨透镜像面位置获得高质量的光刻图形,采用超分辨透镜-光刻胶-反射银膜的结构方式,解决由于超透镜磁场偏振传输模式带来的成像光场畸变问题,大大提高了成像质量和光场对比度.采用掩模图形结构预补偿的方法,消除超分辨透镜的倍率畸变像差...     

光学超分辨及其在光储存中的作用

当前的社会处于移动信息时代,对于新兴储存技术有着非常高的要求。在古代以及近代,采用纸张进行记录与储存,而随着时代的发展,微缩照相储存以及光盘储存不断的兴起与更迭。而光学超分辨技术是随着时代发展而不断完善的信息储存技术,在光储存中有着不可比拟的作用。文章针对光学超分辨进行分析,对其在光储存中的作用进行探讨。     

超分辨弱旁瓣硅基超构透镜

超表面是一种空间变化的超薄纳米结构,在光学超分辨聚焦透镜或系统中已经得到广泛研究和应用。然而,随着超构透镜聚焦光斑缩小,不可避免产生大旁瓣,限制了透镜视场和应用潜力。本文提出了一种设计大数值孔径(NA=0.944)超分辨弱旁瓣超构透镜的方法。针对波长λ=632.8 nm的圆偏振光,基于硅基超表面PB相位调控,实现了超分辨弱旁瓣点聚焦超构透镜。实验证明,可以实现聚焦光斑半高全宽FWHM=0.45λ,小于衍射极限0.53λ(衍射极限为0.5λ/NA),旁瓣比Sidelobe Ratio(SR)=0.07。该透镜的应用有望实现超分辨光学器件或系统微型化、轻量化和集成化。     

基于光频双曲超材料的无标记远场超分辨显微成像

超分辨光学显微成像技术具有非接触、无损伤等优点。现有超分辨成像手段大多依赖荧光染料,限制其应用场合。近年来基于频谱平移原理的无标记远场显微成像手段被提出,但其分辨率受限于波导材料折射率。利用双曲超材料(hyperbolic metamaterials,HMM)的空间频率带通滤波特性,结合亚波长光栅,激发大面积均匀高频体等离激元(bulk plasmon polariton,BPP)照明场,得益于照明的高波矢量,物体的高频信息可以转移到传统成像系统的通带,为远场图像提供亚波长空间信息。基于该方法,采用0.85数值孔径标准物镜,532 nm波长下2.66k₀横向波矢的BPP照明中心距为100 nm双缝结构成像,横向分辨力提高至λ/5.32。进一步提高BPP的横向波矢可使分辨力提升至λ/7.82。该方法无需标记,便于与传统显微镜集成,为生物医学、芯片工业、材料科学等领域的应用提供了一种可视化的超分辨手段。     

两种超分辨ISAR成象算法

为提高逆合成孔雷达（ＩＳＡＲ）图象的分辨率,本文介绍了连续Ｈｏｐｆｉｅｌｄ神经网络和ＥＳＰＲＩＴ两种超分辨技术。通过对实验ＩＳＡＲ回波数据的处理表明,与常规的ＦＦＴ算法以及普通超分辨成象算法相比较,这两种新算法明显地提高了图象分辨率。     

智能超材料研究与进展

本文以智能超材料关键技术为主线,基础研究和新产品研发为辅,简要论述近年来智能超材料的发展现状和趋势。根据智能超材料所调控激元的不同,可分为智能电磁超材料,智能机械超材料,智能热学超材料,智能耦合超材料,此外两项关键技术为智能超材料新型设计与仿真技术和材料制备技术与材料基因工程。这些智能超材料在科学基础研究方面涉及超材料中多物理场耦合机制,新型人工原子与人工分子设计,超材料与自然材料的融合,超材料可调性探索和新型传感型超材料机制探求。基础研发和技术拓展将推进智能超材料施展到更加广泛的应用领域,如微型天线及无线互联,光电磁隐身,医学图像上用的完美成像,航空航天和交通车辆所用的智能蒙皮,精密仪器制程与片上实验室集成型超材料等。基于上述国内外智能超材料研究的发展趋势,本文进行了系统性的分类厘清,并分析了其研究现状,给出了我国智能超材料发展的美好愿景。     

基于变分贝叶斯多图像超分辨的平面复眼空间分辨率增强

平面复眼成像系统利用多个子孔径对场景进行成像,由于子孔径大小和图像传感器空间采样率的限制,各子孔径图像质量较差。如何融合多个子孔径图像来获得高分辨率图像是亟需解决的问题。多图像超分辨理论利用多幅具有互补信息的图像来重构高空间分辨率图像,然而现有理论通常采用过于简化的运动模型,这种简化的运动模型对平面复眼成像并不完全适用。若直接把现有多图像超分辨理论用于平面复眼分辨率增强,不准确的相对运动估计将降低图像分辨率增强性能。针对这些问题,本文在变分贝叶斯框架下改进了现有多图像超分辨理论中的运动模型,并把导出的联合估计算法用于平面复眼分辨率增强。仿真数据实验和真实复眼数据实验验证了推荐方法的正确性和有效性。     

磁光超分辨近场结构存储技术

介绍分析了近场存储基本原理和现状，对实现磁光近场存储的一种新方法－磁光超分辨近场结构的应用原理、最新进展及发展方向进行了综述。     

高端光学元件超精密加工技术与装备发展研究

高端光学元件是决定高端装备性能水平的核心零件，研究高端光学元件超精密加工技术与装备发展，对于实施制造强国战略、满足高端装备产业需求具有积极意义。本文剖析了光学元件超精密加工方法与装备、高性能基础部件、超精密光学加工中的测量方法与装备等的发展情况，凝练了精度与尺寸极端化、形状与性能一体化、加工工艺复合化、加工与检测一体化、装备与工艺智能化等发展趋势。通过广泛的行业调研和研讨，从需求、目标、产品、关键技术、应用示范、支撑保障等方面着手，形成了面向2035年我国高端光学元件超精密制造技术路线图。针对性提出了优化创新体系设置、组织优势资源成立技术联盟，加大资源保障力度、布局基础研究和技术攻关计划，加强人才培育、构建梯队并扩大队伍规模，筑牢产业发展基础、培育龙头企业和专精特新“小巨人”企业等发展建议，以期促进高端光学元件加工产业提升与高质量发展。     

光子扫描隧道显微镜探测场的数值模拟计算

对光子扫描隧道显微镜（ＰＳＴＭ）的显微成象机理。扫描探测模型做了较为系统的分析和论述。针对具体的探测模型，利用微机编程计算ＰＳＴＭ探测光场的空间分布，并对场分布随扫描控制参量的变化规律进行系统的研究，得到了与实际探测结果一致的分布规律，最终为ＰＳＴＭ的显微成象技术提供了更为具体的理论指导。     

Far-field optical superlens

Far-field optical lens resolution is fundamentally limited by diffraction, which typically is about half of the wavelength. This is due to the evanescent waves carrying small scale information from an object that fades away in the far field. A recently proposed superlens theory offers a new approach by surface excitation at the negative index medium. We introduce a far-field optical superlens (FSL) that is capable of imaging beyond the diffraction limit. The FSL significantly enhances the evanescent waves of an object and converts them into propagating waves that are measured in the far field. We show that a FSL can image a subwavelength object consisting of two 50 nm wide lines separated by 70 nm working at 377 nm wavelength. The optical FSL promises new potential for nanoscale imaging and lithography.     

Photon scanning-tunneling microscopy of unstained Mammalian cells and chromosomes

The photon scanning-tunneling microscope (PSTM) yields optical topographical images of samples that are thin or that are transparent at the wavelength used. A range of sample sizes can be imaged extending to well below the diffraction limit for sufficiently flat samples. But samples of the order of several to many micrometers in size can be analyzed with less-refined resolution if total internal reflection can be made to occur in the sample. We used the PSTM to examine the optical topography of mouse and human cells and of chromosomes that are unstained. Our objectives were to demonstrate the images as an alternative to conventional microscopy and to provide a sample-preparation methodology that will later permit localized, simultaneous fluorescence or absorption spectroscopy with the signals collected by the probe tip. Furthermore, the PSTM's ability to produce optical profiles in air and in water was tested to establish the basis for future investigation of possible abnormalities in the chromosomes. That is, we considered both physical and biological objectives. To this end we utilized the 442-nm line of a He-Cd laser as well as the 633-nm line from a He-Ne laser, the resulting image quality being tested partly to ascertain the increased effects of scattering at the smaller wavelength. It is shown that adequate resolution and signal-to-noise ratio can be obtained with the shorter wavelength even in the presence of intensity fluctuations from the laser, thus showing that fluorescence and absorption studies can be expected to be practicable.     

Application of Mie Scattering of Evanescent Waves to Scanning Tunnelling Optical Microscopy Theory

Abstract

In this paper we present a macroscopic theory for scanning tunnelling optical microscopy where the sample is a grating and the tip is modelled by a dielectric sphere. The sphere is immersed in the near-field above the grating and is excited by the diffracted orders which can be evanescent. The detected signal is supposed to be the diffracted intensity by the sphere which is calculated by using Mie theory. When studying Mie scattering of one evanescent wave we show that the multipolar series is perturbed compared to scattering of a homogeneous wave. Even for a small sphere multipolar terms have to be taken into account. We have then proposed a formula for the intensity leading to calculations of intensity profile and surfaces and to discuss the influence of tip radius on resolution of the images.     

Direct measurement of standing evanescent waves with a photon-scanning tunneling microscope

We present a detailed analysis of a standing evanescent wave that is caused by total internal reflection of an Ar-ion laser beam on a glass prism and investigate the coupling to a subwavelength dielectric tip of a photon-scanning tunneling microscope that is raster scanned at a close distance over the prism surface. The intensity of the evanescent field is spatially modulated with a period of 239.2 nm. It decays exponentially with a constant of 103.9 nm with increasing distance from the prism surface. Precise measurements of the standing evanescent wave can be used to calibrate the scanner and permit one to determine the spatial resolution and the coupling efficiency of the tip.     

多盲孔缺陷的超声兰姆波时域拓扑能量成像方法研究

传统超声成像方法受瑞利准则的约束，难以对缺陷间距小于成像分辨率阈值的多缺陷进行成像。提出了一种基于时域拓扑能量的超声兰姆波成像方法，将逆散射拓扑成像方法中的拓扑渐进过程转换成求解直接声场和伴随声场。然后通过将伴随声场进行时间反转，两个声场将具有在缺陷处聚焦，在非缺陷处不聚焦的特性。将直接声场和伴随声场进行融合，以时域拓扑能量值作为像素值进行成像，从而使表征缺陷的精度较高。建立了缺陷间距小于分辨率阈值的多盲孔缺陷有限元模型，通过“一发多收”的方式激发S0模式和采集缺陷散射信号，并进行时域拓扑能量成像。仿真结果表明：对于多盲孔缺陷，时域拓扑能量成像法能够获得比延时叠加法和时间反转成像法更高的分辨率，并且能在缺陷间距小于成像分辨率阈值时进行成像。     

Quantitative flaw reconstruction from ultrasonic surface wavefields measured by electronic speckle pattern interferometry

A new method for imaging flaws in plate and shell structures is presented. The method employs two-dimensional ultrasonic surface wave data obtained by optical electronic speckle pattern interferometry (ESPI) techniques. In the imaging method, the measured out-of-plane displacement field associated with an externally excited ultrasonic Lamb wave is processed to obtain the spatial frequency domain spectrum of the wavefield. A free space Green's function is then deconvolved from the wavefield to obtain quantitative images of effective scattering sources. Because the strength of these effective sources is directly dependent on local variations in sample thickness and material properties, these images provide a direct map of internal inhomogeneities. Simulation results show that the method accurately images flaws for a wide range of sizes and material contrast ratios. These results also demonstrate that flaw features much smaller than an acoustic wavelength can be imaged, consistent with the theoretical capability of the imaging method to employ scattered evanescent waves. Reconstructions are also obtained from ultrasonic Lamb wave displacement fields recorded by ESPI in a flawed aluminum plate. These reconstructions indicate that the present method has potential for imaging flaws in complex structures for which ESPI wavefield measurements cannot be straightforwardly interpreted     

Field enhancement in apertureless near-field scanning optical microscopy.

The near field of an apertureless near-field scanning optical microscopy probe is investigated with a multiple-multipole technique to obtain optical fields in the vicinity of a silicon probe tip and a glass substrate. The results demonstrate that electric field enhancements of >15 relative to the incident fields can be achieved near a silicon tip, implying intensity enhancements of several orders of magnitude. This enhancement arises both from the antenna effect of the elongated probe and from a proximity effect when the probe is near the substrate surface and its image dipoles play a role.     

Spiral hyperlens with enhancements of image resolution and magnification

Abstract

A subwavelength spiral hyperlens that is able to image beyond the diffraction limit is studied. The spiral hyperlens is made from an anisotropic metamaterial with a hyperbolic dispersion relation in which the evanescent wave is converted into a propagating wave. Therefore, the propagating wave can be processed by conventional optical systems outside of the spiral hyperlens. The possibility of using a cylindrical hyperlens for overcoming the diffraction limit has been proven analytically and experimentally. In this study, we designed two types of spiral hyperlenses composed of a spiral periodic stack of silver and alumina multilayers. A spiral hyperlens utilizes the spiral geometry to magnify the objects. In comparison with a cylindrical hyperlens, a spiral hyperlens has improved performance in terms of higher image resolution and better image magnifications. Numerical simulations illustrate that the far-field imaging resolution of cylindrical spiral hyperlens is no greater than 110 nm at 365 nm working wavelength.     

近场光镊与AFM探针复合的光阱力分析

本文针对纳米材料的纳米操作,提出了一种复合激光近场光镊与AFM探针进行纳米操作的方法,并基于动量守恒原理,采用三维时域有限差分方法建立了该方案中激光近场对纳米微粒的作用力模型,分析了各轴向光阱力的分布情况,讨论了两探针间距离、针尖材料的电导率、入射平面光场的偏振方向、入射角和波长等参数对近场光阱力的影响.结果表明:位于...