共查询到19条相似文献,搜索用时 156 毫秒
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在同时考虑样品的形貌及材料光学参量和入射光偏振模式的情况下,利用基于边界元方法编写的二维矢量电磁场计算程序,对工作在照明模式下的扫描近场光学显微镜(Scanning Near-field Optical Microscope,SNOM)的近场矢量电磁场分布进行了数值计算模拟研究.结果表明,在没有表面形貌特征时,探针的光能量透射率随样品材料的折射率和损耗角的增加而增大,而样品表面光斑尺寸受折射率和损耗角的影响很小;对有形貌特征的探针扫描像研究结果表明,SNOM的分辨率随着样品的折射率和损耗角的增加而提高;对SNOM不同的工作模式的扫描成像信号进行的计算结果表明,恒定间距扫描方式比恒定高度扫描方式对样品表面的细节有较强的分辨能力. 相似文献
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为了研究扫描近场光学显微镜中探针和粗糙样品表面的耦合相互作用,提出了一种光耦合偶极子模型.在该模型中,探针和样品突起都由光极化偶极子表示,在准静态电磁场近似的情况下样品表面的诱导极化效应由影像偶极子表示,应用偶极子辐射理论可以得到系统的自洽场方程.此模型提供了一种直观分析扫描近场光学显微镜中探针和样品相互作用机理的方法.在此基础上,进一步讨论了金属样品的近场成像特点和其特有的局域光学共振现象.数值结果表明:不同于一般的介质样品,金属样品的近场图像与入射光频率直接相关,改变入射光的频率,获得的样品近场图像的形状和对比度都会发生变化.特别是当入射光频率处于样品极化共振范围内时,金属纳米粒子的极化率会出现光极化共振,这样就可以获得样品粒子的最大有效尺寸,为提高系统的分辨率提供了一条重要途径. 相似文献
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近场光学是指当光探测器及探测器-样品间距均小于辐射波长条件下的光学现象.利用近场光学扫描显微镜和近场光谱仪,不但能够以突破衍射极限的超高分辨率在纳米尺度实现光学成像,而且还可获得纳米微区的光谱信息.文章介绍近场光学的原理及其在凝聚态物理领域中的应用与进展,并给出了我们的初步结果 相似文献
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纳变尺度的光学成像与纳米光谱:近场光学与近场光学显微镜的进展 总被引:6,自引:0,他引:6
近场光学是指当光探测器及探测器一样品间距均小于辐射波长条件下的光学现象,利用近场光学扫描显微镜和近场光谱仪,不但能够以突破衍射极限的超高分辨率在纳米尺度实现光学成像,而且还可获得纳米微区的光谱信息,文章介绍近场光学的原理及其在凝聚态物理领域中的应用与进展,并给出了我们的初步结果。 相似文献
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在近场扫描光学显微镜(NSOM)^[1]中,近场距离控制一般要用切向力控制法。检测切向力有两种方法:光学检测法和非光学检测法。目前普遍采用非光学检测法,基本上是采用压电陶瓷管控制探针和样品的距离。本文提出一种新的切向力检测系统,利用双压电片实现近场距离控制。实验结果表明,检测灵敏度大大提高,扫描力显微(SFM)像的分辨率可达纳米量级。 相似文献
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使用实验室自制的低温近场光学显微镜研究了InGaN/GaN多量子阱发光二极管在室温和液氮 温度下的近场光学像和近场光谱,发现随着温度的降低,不仅近场光学像的光强起伏大大减 小,量子阱发光峰先蓝移后红移,而且在液氮温度下在光子能量更高的位置上出现了新的发 光峰.通过对实验结果的分析,我们将这个新出现的峰归结为p-GaN层中导带底-受主能级间 跃迁形成.
关键词:
InGaN/GaN多量子阱
发光二极管
近场光学
低温 相似文献
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光声成像是21世纪初发展起来的新兴的生物医学成像技术,它同时具备光学成像和声学成像两者的优点,因而备受关注。本文对生物医学光声成像的发展进行了综述。首先,介绍了光声成像的特点以及相对于广泛应用的光学成像技术和声学成像技术的优点;其次,在成像原理上解释了光声成像优点的成因,并介绍了光声断层成像和光声显微镜这两种典型的光声成像技术;再次,详细介绍了多尺度的光声图像分辨率和成像深度,以及多信息维度的光声成像参数;最后,展望了光声成像在生物医学领域的应用潜力并讨论了其局限性。 相似文献
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SFM/SNOM结合的扫描探测显微镜 总被引:3,自引:0,他引:3
采用光纤探针的扫描近场光学显微镜 (SNOM)存在某些弱点 ,如探针特别脆 ,不易贴近样品表面扫描 ,探针的转输效率低等。近年来发展了将SFM /SNOM结合起来的扫描探测显微镜。利用微加工工艺技术 ,将小孔集成在悬臂探针中 ,使探针既能批量制备 ,又具有很好的重复性。探针悬臂在垂直于样品表面方向上的弹性常数较小 ,针尖不易损坏。在接触模式中利用这种SFM /SNOM组合探针可将样品的形貌像、摩擦力和光学透射像等信息同时记录下来。对于综合研究样品表面的介观性质十分有利。 相似文献
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In a previous paper we proposed a modification of metal-coated tapered-fibre aperture probes for scanning near-field optical
microscopes (SNOMs). The modification consists in radial corrugations of the metal-dielectric interface oriented inward the
core. Their purpose is to facilitate the excitation of surface plasmons, which increase the transport of energy beyond the
cut-off diameter and radiate a quasi-dipolar field from the probe output rim. An increase in energy output allows for reduction
of the apex diameter, which is the main factor determining the resolution of the microscope. In two-dimensional finite-difference
time-domain (FDTD) simulations we analyse the performance of the new type of SNOM probe. We admit, however, that the two-dimensional
approximation gives better results than expected from exact three-dimensional ones. Nevertheless, optimisation of enhanced
energy throughput in corrugated probes should lead to at least twice better resolution with the same sensitivity of detectors
available nowadays. 相似文献
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Numerical simulations have been carried out in the framework of waveguide theory to model collection mode scanning near-field
optical microscopy (SNOM). The theoretical model includes the optical fiber end and describes the metal coated aperture on
the probe tip. The developed formalism goes beyond the existing Bethe-Bouwkamp theories for electromagnetic transmission of
subwavelength apertures. The finite coating and optical fiber end are now taken into account. The new features enable us to
simulate the near-field probes that are widely used in the collection mode SNOM. The emphases of the numerical analyses have
been mainly on the resolution mechanism of the microscopy. Influence on the resolution from important parameters of the probe
tips, such as the size of the apertures and the probe-sample distance, is extensively studied. The resolution dependence has
been analyzed in the light of the near-field coupling efficiency of the probe tip. An optimum tip size has been found which
is balanced between the significant signal transmission and the resolution of the device. 相似文献
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Sumio Hosaka Toshimichi Shintani Atsushi Kikukawa Kenchi Itoh 《Applied Surface Science》1999,140(3-4):388-393
We study a nanometer-sized optical probe and image in a scanning near-field optical microscope (SNOM). We demonstrated the potential to observe 5-nm wide optical patterns using the SNOM. The probe profile was measured by using a knife-edge method and a modulated transfer function evaluation method. An aluminum covered and pipet-pulled fiber probe used here has two optical probes, one which has a large diameter of 350 nm and one which has a small diameter of around 10 nm. 相似文献
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We report on the development of a cantilever-based scanning near-field optical microscope (SNOM) working in an extreme environment,
at cryogenic temperature around 10 K and under strong magnetic field up to 7 T. We designed a new optical system based on
an infinite conjugate microscope, which extracts the near-field signal from a small aperture through a narrow chamber into
free space as collimated light. Using this system, we successfully measured near-field and topographical images of a metal-hole
sample simultaneously. Combining the local optical accessing technique with the external control of the electronic state,
this SNOM system will be a powerful tool to study optical properties of semiconductor nanostructures. 相似文献
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近场光学显微镜中利用剪切力原理进行样品/探针间距测控的非光学方法 总被引:1,自引:0,他引:1
扫描近场光学显微镜(ScanningNear-fieldOpticalMicroscope:SNOM)自80年代中期以来获得了迅速的发展并得到了具有纳米(亚纳米)尺度分辨率的光学图像。作为SNOM的关键技术之一,样品与探针间距的控制尤为重要,而实现起来比较困难。人们提出了多种方法,其中基于剪切力原理的控制方法最常用而且实验证明是可靠的。本文综述了扫描近场光学显微镜发展以来所出现的基于剪切力原理进行样品/探针间距的探测的一些主要的非光学方法。包括利用PMT直接探测样品辐射,利用音叉、电容、阻抗以及压电效应的探没方法等,并对各种方法的优缺点进行了分析比较。 相似文献
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Influence of the probe--sample interaction on scanning near-field optical microscopic images in the far field 下载免费PDF全文
We have studied the influence of probe--sample interaction in a scanning near-field
optical microscopy (SNOM) in the far field by using samples with a step structure.
For a sample with a step height of $\sim \lambda $/4, the SNOM image contrast
between the two sides of the step changes periodically at different scan heights.
For a step height of $\sim \lambda $/2, the image contrast remains approximately the
same. The probe--sample interaction determines the SNOM image contrast here. The
influence of different refractive indices of the sample has been also analysed by
using a simple theoretical model. 相似文献
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ZHANG Guoping MING Hai CHEN Xiaogang YANG Bao XIE Jianping 《Chinese Journal of Lasers》1997,6(6):513-517
ExperimentResearchesonActiveFibreProbeforScanningNearfieldOpticalMicroscopyZHANGGuopingMINGHaiCHENXiaogangYANGBaoXIEJianpin... 相似文献