共查询到20条相似文献,搜索用时 31 毫秒
1.
The construction and imaging capabilities of a scanning high resolution ultrasonic microscope are considered in this paper. Theoretical expressions for the resolution limits of the microscope and some of the most important properties of the ultrasonic lenses are given. Ultrasonic through-transmission and back-scattering images of different objects are presented and a quasi-three-dimensional display mode is introduced. A resolution of about 4 μm is demonstrated at 300 MHz by the present ultrasonic microscope. 相似文献
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Enhancement of resolution in electron microscopy can be achieved by use of electron image holography. In order to compensate for the aberrations of the electron lenses the reconstruction is performed with laser light in an optical system with suitably adapted aberrations. The partial coherence in connection with the aberrations of the electron lenses limits the possible resolution. The limits of resolution dependent on defocusing and spherical aberration are calculated. 相似文献
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H. Y. Barminova 《Physics of Atomic Nuclei》2017,80(11):1665-1668
The possibility of using high-energy proton radiography for dense plasma diagnostics is discussed. The designed telescopic ion optical system for a proton radiography installation with a 1 GeV beam is presented. The schematic diagram of the proton microscope is given. It is shown that the estimate of spatial resolution for the installation obtained with consideration of chromatic aberrations of magnetic quadrupole lenses is limited from below. 相似文献
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Werner Jark 《Journal of synchrotron radiation》2012,19(4):492-496
Refractive lenses focus X‐rays chromatically owing to a significant variation of the refractive index of the lens material with photon energy. Then, in combination with an exit slit in the focal plane, such lenses can be used as monochromators. The spectral resolution obtainable with refractive lenses based on prism arrays was recently systematically investigated experimentally. This contribution will show that a wide‐bandpass performance can be predicted with a rather simple analytical approach. Based on the good agreement with the experimental data, one can then more rapidly and systematically optimize the lens structure for a given application. This contribution will then discuss more flexible solutions for the monochromator operation. It will be shown that a new monochromator scheme could easily provide tuning in a fixed‐exit slit. 相似文献
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由于衍射极限的存在,传统光学透镜成像分辨率理论上只能达到入射光波长的一半。通过恢复和增强携带物体细部特征信息的高频倏逝波,基于表面等离子体的平面金属透镜有望突破这种光学衍射极限,实现超分辨成像。本文对平面薄膜式与纳米结构式两类平面金属透镜进行了综述,详细介绍了若干典型平面金属透镜的结构设计、工作机理及其聚焦性能,并对其特点与存在的问题进行了分析与讨论。由于光波在金属中传播时存在一定损耗,如何更高效地增强高频倏逝波信号并转换成传播波,使其参与成像,以更好地实现远场超分辨成像,以及如何进一步增大近场超高分辨率聚焦光斑焦深以及减小远场聚焦光斑尺寸,是表面等离子体平面金属透镜进一步研究的重点。 相似文献
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Evans-Lutterodt K Stein A Ablett JM Bozovic N Taylor A Tennant DM 《Physical review letters》2007,99(13):134801
We have fabricated and tested a compound lens consisting of an array of four kinoform lenses for hard x-ray photons of 11.3 keV. Our data demonstrate that it is possible to exceed the critical angle limit by using multiple lenses, while retaining lens function, and this suggests a route to practical focusing optics for hard x-ray photons with nanometer scale resolution and below. 相似文献
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渐进多焦点眼用镜片的子午线设计研究 总被引:5,自引:1,他引:5
介绍渐进多焦点眼用镜片的构造,论述镜片的设计思想,阐述渐进多焦点眼用镜片子午线设计的基本原理,构建子午线多项式,给出子午线设计需满足的准则.在子午线设计的基础上,设计渐进多焦点眼用镜片等屈光度轮廓线,确定镜片面形,并求出镜片平均球面度与像散.比较3种不同子午线设计的渐进多焦点眼用镜片,并进行实际加工与检测.研究结果表明,子午线设计是渐进多焦点眼用镜片设计的关键之一,不同的子午线屈光度分布,对应的渐进多焦点眼用镜片的球面度、像散以及畸变等差别较大.依据实际设计与检测结果,给出适用于不同个性化需求的渐进多焦点眼用镜片子午线屈光度分布的规律. 相似文献
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为了获得高分辨率、高对比度和低畸变的掌纹图像,同时实现系统的轻量化和高性价比,本文基于全反射原理,采用树脂材料设计了一款由6片镜构成双远心光路的掌纹采集光学系统。树脂材料的选用减轻了光学系统的总重量;基于光的全反射原理的系统设计增强了掌纹图像的对比度;选择双远心光学结构,便于对倾斜物面所产生的梯形畸变进行矫正。对所设计光学系统的成像质量分析表明,该系统所有视场的光学传递函数(MTF)在Nyquist频率228 lp/mm处均达0.55以上,畸变〈0.14%。设计的光学系统可以采集120 mm×160 mm的手掌区域,实际手掌面上的分辨率达到500dpi,采集的掌纹图像分辨率达到8.0×106 pixel,满足了实际采集的要求。 相似文献
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We report results of 1H NMR transverse relaxation experiments on human and porcine eye lenses. Several authors have reported that transverse relaxation is not mono-exponential when observed by the Carr-Purcell-Meiboom-Gill (CPMG) sequence and have interpreted the results by postulating the presence of "pools" of water molecules in different binding environments that do not exchange rapidly on the NMR timescale. We have compared CPMG data for intact lenses with results for lens homogenates and have combined a CPMG spectroscopic pulse train with NMR micro-imaging to study the nature of the transverse relaxation process in human and porcine lenses. Fast exchange of water protons with the lens proteins (crystallins) leads to an enhanced transverse relaxation rate that varies linearly with protein concentration. At the resolution of NMR micro-imaging the transverse relaxation process is mono-exponential. The results show that the multi-exponential CPMG data observed spectroscopically for whole lenses reflect spatial variations in crystallin content through the lens rather than the presence of distinct "bound" and "free" water pools. 相似文献
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介绍并表征了一套单法兰集成的低能电子显微镜. 这套显微镜中采用了10o偏转角的磁分束器,从而有利于将其集成到一个10 in的法兰上. 电子光学系统中的一些修正单元被简化,以使其结构简单,容易操作. 样品被置于地电位,方便各静电透镜浮在高电压上. 通过几个实验展示了这台显微镜在典型的低能电子成像、低能电子衍射和光电子成像模式下的性能. 低能电子成像的空间分辨率为51 nm. 利用飞秒激光做光源,相应的非线性光电子发射过程使得这台设备非常适合进行光学近场现象的观察,并获得110 nm的光电子成像空间分辨率. 相似文献
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We have developed a miniature scanning confocal microscope that uses electrostatically actuated microlenses for focusing and scanning. Objective lenses, scanners, a pupil, and a pinhole of the confocal microscope are microfabricated and integrated into a volume smaller than 2 mm3 by stacking these components. Objective lenses are composed of two vertically cascaded polymer microlenses integrated into micromachined comb actuators. Raster scanning is implemented by electrostatically actuating each microlens in orthogonal directions. We have demonstrated reflection confocal imaging with 3-microm transverse resolution over a 100-microm field of view and a 0.38-mm working distance at lambda = 633 nm. 相似文献
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Chao W Anderson E Denbeaux GP Harteneck B Liddle JA Olynick DL Pearson AL Salmassi F Song CY Attwood DT 《Optics letters》2003,28(21):2019-2021
A spatial resolution of 20 nm is demonstrated at 2.07-nm wavelength by use of a soft x-ray microscope based on Fresnel zone plate lenses and partially coherent illumination. Nanostructural test patterns, formed by sputtered multilayer coatings and transmission electron microscopy thinning techniques, provide clear experimental results. 相似文献
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Advanced dioptric projection lenses from Carl Zeiss are used in some of the world’s most advanced deep ultraviolet projection lithography systems. These lenses provide a resolution of better than 100nm across the entire field of view with a level of aberration control that maximizes critical dimension uniformity and lithographic process latitude. These dioptric projection lenses are currently being used for critical layer device patterning for a wide array of complex logic, memory, and application specific integrated circuits. 相似文献
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YU Qing-Chang 《中国物理C(英文版)》1989,13(2):106-108
In this paper,the methods for transforming strip ion beams into axisymmetrical beams with given focusing properties by means of thin quadrupole lenses,axisymmetrical thin lenses and deflecting magnets are discussed. 相似文献
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本文对电磁复合聚焦阴极透镜的象差理论进行评述与研究,着重分析西门纪业和Бонштедт两篇代表性的文章,详细推导了两文的象差方程和象差系数。研究表明,尽管两文的象差系数在形式上迥然不同,但实质上是完全一致的,是可以互相转化的。从而证明Бонштедт对西门纪业的批评是没有根据的。按照我们的研究,成象系统的象差应在某一轴向初电位ε(x1)而非εx所对应的象面上进行考察,从而导出电磁复合聚焦阴极透镜包括一级象差与三级象差在内的全部横向象差表达式
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The chromatic aberration of magnetic lenses with the field distribution in the forms of inverse law have been studied by analytical and digital methods. These aberrations can be expressed in terms of Bessel function of fraction order. Analytical expressions for chromatic aberration coefficients of the spherical field model, which is useful for the study of single-pole magnetic lenses, are given. 相似文献