光纤剖面折射率分布测量新方法

本文在简述逆几何不迩理论基础上,讨论了如何结合计算机图像处理技术根据光线轨迹得出光媒质的剖面折射率分布方法,并且用在改型干涉显微镜基础上建立的ＣＣＤ摄像显微镜实验装置作出验证,从而也提出一种光纤剖面折射率分布测量的简便,易行,精度可靠的新方法。本文介绍的新方法对如何保证目前已被越来越普遍地应用于光通讯和光纤传感器中光纤性能的主要参数检测有十分显著的意义。     

A multiline method of network analyzer calibration

The author presents a method for the calibration of network analyzers. The essential feature is the use of multiple, redundant transmission line standards. The additional information provided by the redundant standards is used to minimize the effects of random errors, such as those caused by imperfect connector repeatability. The resulting method exhibits improvements in both accuracy and bandwidth over conventional methods. The basis of the statistical treatment is a linearized error analysis of the TRL (thru-reflect-line) calibration method. The analysis presented is useful in the assessment of calibration accuracy. It also yields results relevant to the choice of standards.<>     

New method for measuring V-value of a single-mode optical fibre

A simple method is proposed for the direct measurement of the V-value for a single-mode optical fibre. This method consists of measurement of loss peaks, corresponding to cutoff wavelengths of the higher modes, which are easily observed for a fibre with a bend.     

A high resolution method for measuring hot carrier degradation in matched transistor pairs

A new measurement methodology has been developed in order to perform high-resolution measurements of the hot carrier degradation on MOSFET's. With this methodology, degradations as low as 0.01% can be measured accurately. The high resolution measurements are necessary for measuring hot carrier degradation in matched transistor pairs. This is demonstrated by comparing the degradation at different stress conditions. A linear extrapolation is not applicable when extrapolating the degradation curves from 1 % to 100 ppm.     

近地轨道飞行器载波多普勒频偏估计新方法

对于近地轨道飞行器与卫星之间的通信链路,信号收发两端之间的相对运动导致载波存在高动态的多普勒频偏。另外,信号的远距离传输使得信号很微弱,这就极大地降低了信噪比。为了解决低信噪比和高动态环境下的多普勒频偏估计问题,提出一种多累积周期估计方法,提高多普勒频偏检测概率。该方法利用多个信号累积周期来缩小下一个累积周期内谱峰检测的频率区间,进而提高多普勒估计性能。理论分析和仿真结果表明,与现有方法相比,提出的多累积周期估计方法不仅可以提高检测概率而且可以减小估计误差。     

New method of calibrating a network analyser

A method is described for calibrating a network analyser when the ports used in transmission measurements are not accessible to have their errors characterised by reflection measurements.     

LMR 16-a self-calibration procedure for a leaky network analyzer

A thru-match-reflect/line-match-reflect (TMR/LMR) self-calibration procedure based on the 16-term error model is shown. The error model takes into account all the leakage paths of a wafer prober, test fixture, and network analyzer. Simple closed-form calibration equations are presented. The method is very robust-zero leakage paths and symmetrical or matched-error networks can be handled equally well as more general cases. The algorithm is suitable for nonleaky network analyzers as well. The calibration is comprised of two-port measurement of the following standards: T(L), M-M, R-R, R-M, M-R. Two matched loads (M) are the only standards that have to be known in addition to the thru (T) or line (L). The reflection coefficient of the two identical reflection standards (R) is found in addition to the error parameters as in the normal TMR method. Experimental measurements with the LMR 16 have been made. All the possible combinations of five calibration standards for the 16-term error model are tabulated. The limitations of the super-thru-short-delay algorithm are defined for the first time     

一种测量外延层厚度及掺杂浓度的改进方法

在双台面SiGeHBT加工工艺过程中,采用RIE工艺刻蚀发射极台面时,为了避免等离子轰击对外基区表面造成损伤,同时为了防止过刻到基区,必须严格控制发射极台面的高度,从而必须准确知道未刻蚀前的厚度和刻蚀后的厚度。现有的许多对材料厚度及掺杂浓度的分析方法,具有各自的优缺点。本文提出了一种可以同时检测外延层的厚度及掺杂浓度分布的方法,这种方法具有简单、高效、低成本的优点。     

提高傅里叶变换轮廓术测量精度的新方法

在傅里叶变换轮廓术 (FTP)测量方法中 ,成像装置获取受到物体高度调制后的变形结构光场 ,通过傅里叶变换 ,滤波和逆傅里叶变换恢复出物体高度分布。频谱滤波是FTP中很重要的一个过程 ,也是影响FTP测量精度的一个重要因素。通常滤波是手工选择合适的滤波函数和滤波窗口大小 ,窗口太小 ,表示物体细节的高频信息将丢失 ;窗口太大 ,无法消除噪声。本文提出一种新的滤波方法 ,无需手工选择滤波函数 ,可以很好地保留物体高频信息并消除随机噪声 ,从而提高FTP的测量精度。计算机模拟和实验证实了所提方法的有效性     

A useful method for approximating the profile of ions implanted through a thin film

An approximate calculation method is presented for finding profiles of ions implanted through a thin film, based on standard range tables. Both the projected range and straggling in the substrate are calculated.     

少数载流子寿命测试系统研究

少数载流子寿命是衡量半导体材料性能的关键参数之一 ,文中介绍了光电导衰退法少数载流子寿命测试系统。阐述了光电导衰退法测试原理 ,分析了测试系统构成 ,以及光脉冲下降沿时间、微弱信号放大处理、前放带宽、精密定位等关键技术 ,其主要性能指标是 :少数载流子寿命测试范围 :1× 10 - 7～ 6× 10 - 6s ;可测样品尺寸 :小于 2 0mm ;单色光光点大小 :Φ 0 .3mm ;测试数据稳定度优于 10 %。     

脚型三维曲面测量技术

提出了一种新的三维曲面测量方法,利用激光片光对脚进行光切,在脚的某一个截面上形成封闭光带,用3个CCD摄像机对截面光带成像,可一次获得脚的某一个截面的二维轮廓信息,再沿光切面的垂直方向步进测量,经CCD摄像机像面和光切平面之间的空间映射变换后可得到脚的整个三维曲面信息。     

New method for measuring ultrawide frequency response of optical detectors

We propose a simple method which allows for a direct measure of the frequency response of photodetectors up to very high frequencies and avoids some of the problems inherent in the standard time-domain or frequency-domain measurements. This method is based on the detection of the tunable beat frequency obtained by superimposing the EM fields of two monomode semiconductor lasers.     

一种新型车载酒精浓度测量仪的设计

采用STC89C52单片机为核心,选用酒精传感器MQ3设计了一种车载酒精浓度测量仪.系统包括液晶显示模块、数据采集模块、A/D转换模块、超标报警模块、按键设置模块和数据存储模块等.利用MQ3输出电压值与酒精浓度值的线性关系来测量酒精浓度值,并对测量结果进行误差分析.设计的车载酒精浓度测量仪能较好地测量驾驶者体内的酒精浓度值,以便提醒驾驶者遵守交通规则,勿酒驾或醉驾,避免交通事故的发生.     

New method for measuring transfer impedance and transfer admittanceof shields using a triaxial cell

Two performance parameters of a cable or connector shield are its surface transfer impedance Z_T and its surface transfer admittance Y_T. A new method for measuring these properties is presented. The use of two different terminations for the cable or conductor under test (CUT) allows one to determine both Z_T and Y_T. Through characterization of the inner and outer transmission lines of the triaxial cell, using time domain reflectrometry, Z_T and Y_T can be determined in amplitude as well as in phase. The phase is obtained by de-embedding the measured S-parameters up to the CUT. The de-embedding of the measurements also allows one to extend the frequency range up to 3 GHz. To illustrate this method a solid shield with a circular aperture and a coaxial cable with a braided shield have been measured and compared, respectively, with theoretical predictions and published results     

Multiport scattering matrix measurement using a reduced-port network analyzer

A novel method for acquiring the scattering matrix of an n-port network from measurements using a reduced-port network analyzer is developed. This method can obtain the scattering matrix of a nonreciprocal or reciprocal n-port network with the use of a three- or two-port network analyzer. The formulation of this method considers the imperfection of terminators used in the measurement, and only two of the terminators are required to be known. Experimental results from a four-port microstrip circuit show good accuracy using the developed method.     

A new implementation of a multiport automatic network analyzer

A generalized multiport network analyzer implemented using commercially available hardware is presented. Measurement calibration is accomplished through a novel calibration procedure which requires only conventional standards used for two-port calibrations. The calibration theory accounts for the errors due to the signal switching network but does not systematically remove errors due to signal switching leakage between port pairs. The approach is verified on a three-port test set implementation, and the measuring system can be expanded to n ports with additional hardware in a straightforward manner. Experimental verification was carried out through measurement of one-, two-, and three-port devices connected to the test set ports in several different ways. Excellent agreement of the same corrected S-parameters measured at different test set ports was observed, and confidence in system accuracy is established through measurement of two-port verification standards     

Unified control infrastructure for carrier network evolution

Migration strategies for the network control infrastructure are discussed, to evolve carrier networks toward an optical transport backbone optimized for IP traffic. The strategies presented aim to protect carriers' investments in their current multiservice and IP-routed networks, while expediting the backbone migration toward a unified packet-over-optical core for IP and multiservice transport. This unified core network simplifies the network layers and control systems, and consolidates data and multiservice traffic to reduce network cost with improved bandwidth efficiency. The network control system, including signaling, addressing, and routing, is analyzed in detail to demonstrate the feasibility of the proposed infrastructure. Built on multiprotocol label switching (MPLS) technology, the presented solutions take phased evolution steps to reduce network cost, improve bandwidth efficiency, and offer practical options for internetworking during the migration. These solutions provide carriers with competitive advantages to consolidate multiple services onto an IP-centric optical transport network. The unified control infrastructure not only offers flexible options for network upgrade with reduced network management overhead, but also supports enhanced networking and traffic engineering capabilities to ensure no compromise in the service level agreement committed to end customers.