扫描近场圆偏振光学显微镜

提出一种利用镀有金属薄膜的V形无孔光学探针构建的扫描近场光学显微镜,将圆偏振光注入镀有金属薄膜的V形槽内在针尖处形成近场照射光源,并利用探针收集样品表面近场光信号。理论分析表明:探针收集的近场和远场反射光之间存在一定的相位差,该相位差与探针机械结构、探针与样品的距离有关,可通过探针与样品之间的距离加以控制,因此利用偏振性器件可有效抑制远场光强。实验中,探针与样品之间的距离通过范德华力回馈控制,探针操作在接触模式,实验结果显示所测近场与远场光相位相差57,近场光学图像横向分辨率优于12 nm。     

近场源DOA、距离和极化参数联合估计新算法

研究近场源波达方向(DOA)、距离和极化参数联合估计问题.利用特殊的线性极化阵列,提出一种基于三阶循环矩的新方法.该方法利用信号的循环平稳特性以及空、时域信息,通过时空矩阵的构造和特征分解获得各参数的闭式解.估计过程中无需谱峰搜索,并且能够抑制任意分布的加性平稳噪声以及具有不同循环频率的干扰信号.计算机仿真实验验证了该方法的有效性.     

Observation of polarization property in near-field optical imaging by a polarization-maintaining fiber probe

We fabricated an original near-field scanning optical microscopy (NSOM) fiber probe made of polarization-maintaining and attenuation-reducing (PANDA)-type polarization-maintaining optical fiber, and observed the polarization property of propagation light in a polymer optical waveguide. The distribution of the transmission coefficient in polarization angles through this NSOM probe showed that the linear polarization is maintained in the two crossing directions: the fast and slow axes. The polarization degree parallel to the slow axis decreases from 1000:1 to 2:1 by bending the fiber probe and the decrease is independent of the bending direction. Using this PANDA-type NSOM probe, we investigated the polarization property of periodic intensity modulation. It was found that the intensity modulation was observed clearly with the electric vector parallel to the radius direction of the waveguide, but was observed vaguely with the electric vector perpendicular to the radius direction.     

近场光学存储器

近场光学存储器采用了纳米高新制作技术,具有极高的读出速度和极高的存储密度。本文介绍了近场光学“头”、近场光学记录方法、记录机理和处理方法以及T比特光盘的制造技术和结构。     

The efficiency of near-field Cassegrainian antennas

The aperture efficiency of a near-field Cassegrainian antenna is approximated with a Fresnel field analysis. Curves are presented which give the efficiency of the system in terms of the amplitude distribution on the feed aperture and the Raleigh distance to the subreflector. It is found that separation between feed aperture and subreflector can be as great asfrac{1}{2}d^{2}/lambdawithout excessive loss.     

Reconstruction of the polarization ellipse of the EM field of Telecommunication and broadcast antennas by a fast and low-cost measurement method

A low-cost measurement method for the extraction of the relative phases of the field of base station and broadcast antennas is presented. Our purpose is to determine the polarization of the field at a measurement site using magnitude measurements only. By determining six amplitude components using a spectrum analyzer, the polarization ellipse of the field can be obtained. This low-cost method can be used for outdoor measurements, which is not possible with network analyzers. Using this method and thus knowing the polarization of the incident field we are able to determine more accurately the actual electromagnetic power absorbed in people at a measurement site.     

Devices used to follow the rotations of the polarization ellipse of an electromagnetic wave : application to the ionospheric Faraday effect

The experimental study of the ionospheric Faraday effect requires the development of polarization measurement systems. Their function is to determine the instantaneous position of the main axis of the polarization ellipse of an electromagnetic wave in a given referential and to follow its rotations on a continuous basis. After a brief summary of the parameters which define the polarization of an electromagnetic wave (emw), we describe the different polarizations techniques used in most equipment. The polarimeters are mainly based upon the processing of the vhf telemetry signals emitted by geostationary satellites and received on a pair of orthogonally linear antennas. The electronic rotation of the antennas is the operating principle common to all these devices. So the receiver involve mixers, phase shifters, filters and phase measurements. A new polarization technique is proposed; it uses a system of digital data processing from the two linear 45°rossed antennas. Software data processing makes it possible to monitor the Faraday rotations in real time and to calculate the corresponding total electronic content of the ionosphere (tec) .     

一种目标区域最佳椭圆描述确定方法

目标的最佳描述区域对于建立目标特征、目标跟踪、目标轮廓求取具有非常重要的意义.针对这类问题,提出了一种目标区域最佳椭圆描述确定方法.新方法首先根据目标和背景的差别确定出目标区域,然后利用尺度空间理论计算出目标的最佳椭圆描述.实验表明,新算法可以有效、准确地确定出目标包含区域的大小和方向.     

Progress of super-resolution near-field structure in near-field optical storage technology

Super-resolution near-field structure (Super-RENS) is one of the most promising near-field optical recording schemes with significant application prospects. The development of Super-RENS from the basic type to the third-generation is introduced. The development of mask material and the application of Super-RENS in different recording systems are summarized.     

Geometric property based ellipse detection method

In this paper a simple but effective and robust ellipse detection method based on geometric property is developed, which mainly utilizes the following two aspects of ellipse geometric information:(1) Points on ellipse contour are position-symmetric and the gradient vectors of one pair of symmetric points are parallel or anti-parallel, the fact of which can be used for ellipse center location. In this part, the inner product in mathematics is introduced to evaluate the extent of parallelism of two gradient vectors, and then two concepts, inner product symmetrical energy (IPSE) and inner product consistent energy (IPCE), is defined to compute the probability of a position as a symmetric center.(2) The sum of distances of one contour point far from ellipse’s two foci is a constant. For two given positions, by computing the distribution of the sum of distances we can validate if they are the correct positions of ellipse foci. Furthermore, ellipse’s semi-major axis can be also estimated from distance distribution on the positions of ellipse foci. After determining the center, foci and semi-major axis of an ellipse candidate, other parameters can be easily deduced by resolving the elliptic equation directly.Compared with existing methods, the proposed method detects the ellipse using the geometric properties directly while avoiding the complicated application of the ellipse parameter space or fitting step, and it is simple, effective and robust. In addition, the ideas proposed in this paper can be extended for other features extraction, such as general symmetry center location and other shapes detection, and extensive experiments show the good availability of the proposed ideas.     

椭圆型孔径几何参数测量

从椭圆坐标变换和边界拟合出发,推导了椭圆几何参数的计算方法,并给出了计算机模拟检测结果。     

The bi-polar planar near-field measurement technique, part II:near-field to far-field transformation and holographic imaging methods

A novel customized bi-polar planar near-field measurement technique is presented in a two-part paper. This bipolar technique offers a large scan plane size with minimal “real-estate” requirements and a simple mechanical implementation, requiring only rotational motions, resulting in a highly accurate and cost-effective antenna measurement and diagnostic system. Part I of this two-part paper introduced the bi-polar planar near-field measurement concept, discussed the implementation of this technique at the University of California, Los Angeles (UCLA), and provided a comparative survey of measured results. This paper examines the data processing algorithms that have been developed and customized to exploit the unique features of the bi-polar planar near-field measurement technique. Near-field to far-field transformation algorithms investigated include both interpolatory and non-interpolatory algorithms due to the a typical arrangement of the bi-polar near-field samples. The algorithms which have been tailored for the bi-polar configuration include the optimal sampling interpolation (OSI)/fast Fourier transform (FFT), Jacobi-Bessel transform, and Fourier-Bessel transform. Additionally, holographic imaging for determination of antenna aperture fields has been incorporated to facilitate antenna diagnostics. Results for a simulated measurement of an array of infinitesimal dipoles and a measured waveguide-fed slot array antenna are included. Appropriate guidelines with respect to the advantages and disadvantages of the various processing algorithms are provided     

Chord bisection strategy for fast ellipse location

It is shown that a previously proposed rapid sampling technique can be extended using a strategy based on chord bisection. The strategy is characterised by very high speed of operation coupled with accurate location, and can be matched to the level of robustness required by the application. The new technique has been tested on images in which the ellipses are cereal grains with close to 2:1 aspect ratio. But it appears to be suitable for locating ellipses of any eccentricity with near ultimate speed of processing     

椭圆曲线的点群阶及其阶的算法

椭圆曲线的点群阶是实现椭圆曲线密码体制的基础与条件。本文针对有限域上的椭圆 曲线,介绍了椭圆曲线点群阶的定义以及所满足的定理,最后比较了两种计算阶的算法--SEA算 法和SST算法。     

The definition of cross polarization

There are at least three different definitions of cross polarization used in the literature. The alternative definitions are discussed with respect to several applications, and the definition which corresponds to one standard measurement practice is proposed as the best choice.     

Scattering-type near-field optical microscopy

A highly promising tool for nanoscale material characterization exploits local optical/infrared light scattering simultaneously with standard atomic force microscopy imaging. Thus, both the topography and the local optical/infrared properties of a sample surface can be mapped at better than 20 nm spatial resolution.     

Comparison of near-field range results

Comparisons of measurements on a contoured beam antenna carried out at five independent European test ranges are presented. They include a compact antenna test range, two cylindrical near-field test ranges, and two spherical near-field test ranges. The comparisons illustrate problems in the determination of gain values and cross polarization, while the agreement in the copolar patterns and the peak directivity is very good     

太赫兹波近场成像综述

太赫兹波成像作为可见光和微波成像等的拓展,在半导体材料表征、生物组织诊断、无损检测和安检等领域表现出许多独特的优点,得到了越来越广泛的关注.传统太赫兹波成像受长波长对应的衍射极限的限制,分辨率较低.而太赫兹波近场成像是目前突破该限制,获得亚微米甚至是纳米量级高分辨图像的研究热点之一.首先介绍了近场机制与成像的基本原理;其次总结了太赫兹波近场成像的几种常用方法及其对应研究进展和当前存在的问题,包括孔径型、针尖型、亚波长太赫兹源型和微纳结构调控型等;最后探讨了该方向的发展趋势.     

超分辨近场结构之纳米光刻技术

超分辨近场结构(Super-RENS)是在传统的超分辨光盘技术和近场光学的基础上发展起来的新技术.介绍了超分辨近场结构的基本原理及其在纳米光刻方面的应用,拓展了超分辨近场结构的外延:在近场范围内,能实现超过衍射极限的纳米多层膜结构.局域表面等离子体效应在高密光存储、纳米光刻等纳米光子学研究领域具有重要的科学意义和应用价值.