子孔径拼接干涉测量一大口径双曲面(英文)

为了无需辅助元件就能够实现对大口径非球面的检测,将子孔径拼接技术与干涉技术相结合,提出了一种利用子孔径拼接干涉检测非球面的新方法.分析了该技术的基本原理,并基于齐次坐标变换、最小二乘拟合建立了一种综合优化的拼接模型,在此基础上初步设计和搭建了子孔径拼接干涉检测装备.利用该方法对一口径为350 mm的双曲面进行了5个子孔径的拼接检测,得到拼接后的全口径面形误差的PV值为0.319λ,RMS值为0.044λ(=632.8 nm).为了对比和验证,对该非球面进行了零位补偿检测,两种方法测量所得的全口径面形分布是一致的,其PV值和RMS值的偏差分别为0.032λ和0.004λ.实验结果表明:该数学模型和拼接算法是准确可行的,从而提供了一种非零补偿测试大口径非球面的手段.     

大口径凸非球面反射镜子孔径拼接检测

为了获得大口径凸非球面反射镜全口径的面形,提出了利用子孔径拼接检测大口径凸非球面的新方法。利用干涉仪标准球面波前依次干涉测定大口径镜面上各个区域的相位分布,通过子孔径拼接算法即可求解得到镜面全口径面形信息。对该方法的基本原理和实现步骤进行了分析和研究,建立了大口径拼接检测算法的数学模型,设计并研制了大口径反射镜拼接检验装置。结合实例对一口径为260 mm 的碳化硅凸非球面反射镜进行了9 个子孔径的拼接干涉测量,并将拼接检测结果与全口径面形测量结果进行对比,两种方法测量面形PV 值和RMS 值的偏差分别为0.043和0.021（=632.8 nm）。     

平面子孔径拼接干涉测量精度分析

如何提高子孔径拼接干涉测量精度是子孔径拼接系统的关键问题。针对一维平面子孔径拼接系统,分别采用两两拼接算法和误差均化拼接算法,进行拼接位移台定位误差、参考面面形误差和随机噪声对拼接精度影响的数值仿真与分析。仿真结果表明,对于平面拼接系统,参考面高阶误差、随机噪声对拼接精度影响较小,高阶误差的影响略大于随机噪声的影响;参考面低阶误差(二阶项误差)在拼接过程中会累积放大,是平面拼接干涉测量的主要误差来源,误差均化拼接算法不能有效控制参考面低阶误差的拼接累积误差;两两拼接算法与误差均化拼接算法得到基本相同的拼接结果。对450mm×60mm的平面镜进行了15个子孔径的拼接测量,去除参考面低阶误差面形前后,拼接结果与大口径干涉仪的测量结果偏差从λ/3[峰谷值(PV),λ=632.8nm]减小至λ/45(PV)。     

高精度平面子孔径拼接算法研究

对平面子孔径拼接累积误差的理论分析及数值仿真表明,参考镜面形的拼接重叠区域的局部斜率差和直流偏差是产生累积误差的原因。为了提高大口径平面光学元件子孔径拼接检测精度,提出一种简单有效的可以减小子孔径拼接测量累积误差的方法,该方法采用第4项和第6项泽尼克像差拟合一个假设的准参考镜面形,再从每个子孔径测量结果中减去,最后拼接合成全口径面形。对450mm×60mm的平面镜进行了8个子孔径的拼接检测,去除准参考镜面形前后,拼接测量结果与Zygo公司24英寸(600mm)口径干涉仪检测结果的偏差峰谷(PV)值从λ/7减小至λ/100。所拟合的准参考镜面形误差为0.02λ(PV值),与标准镜的面形误差为同一量级,其对每个子孔径测量结果的影响可以忽略。实验结果表明,本文方法能够有效控制拼接累积误差,提高拼接检测精度。     

基于非理想标准镜的子孔径拼接干涉检测技术研究

在大口径光学镜面的检测中,随着参考镜尺寸的增加,加工精度的制约,重力变形,温度,环境等因素的影响使得参考镜在检测中已经不能作为理想平面镜。文中基于最大似然估计（ML）算法,Zernike 多项式拟合对利用非理想平面镜作为参考镜的子孔径拼接检测建立了一套合理的拼接算法和数学模型。并结合工程实例,完成了对2.5 m3.5 m 椭圆形平面镜的模拟拼接实验,拼接前后全孔径面形误差分布是一致的,其PV 值和RMS 值的偏差分别为0.022 与0.001 3 。全口径相位分布的PV 值与RMS 值的相对误差分别为2.81%与0.81%。实验结果表明:利用ML 拼接算法可以高精度地完成对参考镜为非理想平面的大口径平面镜的拼接检测。     

子孔径拼接和计算全息混合补偿检测大口径凸非球面(特邀)

为了实现大口径凸非球面的高精度检测,提出了将子孔径拼接检测法和计算全息补偿检测法相结合的检测方法。由于其中心的非球面度较小,采用球面波直接检测;而外圈的非球面度较大,采用子孔径拼接和计算全息混合补偿的方法进行测量,再通过拼接算法将中心检测数据和外圈检测数据进行拼接从而得到全口径面形。结合实例对一块口径为540 mm的大口径凸非球面进行测量,并将检测结果与Luphoscan 检测结果进行对比,两种方法检测面形残差的RMS值为0.019λ,自检验子孔径与拼接结果点对点相减后的RMS值为0.017λ。结果表明该方法能够实现大口径凸非球面的高精度检测。     

夏克哈特曼扫描拼接检测平面镜(特邀)

随着先进光学系统设计与制造的发展,大口径光学系统得到了广泛的应用。然而,大口径平面镜高精度面形的检测手段不足,限制了大口径平面镜的制造与应用。为实现大口径平面反射镜的高精度面形检测,提出一种夏克哈特曼扫描拼接检测平面镜面形的方法。对扫描拼接原理、波前重构算法进行了研究,建立了微透镜阵列成像的数学模型,验证了夏克哈特曼扫描拼接检测原理的可行性。针对一口径为150 mm的平面镜进行了扫描拼接检测实验,拼接得到的全口径面形为0.019λ RMS(λ=635 nm);与干涉检测结果对比,检测精度为0.008λ RMS,结果表明该方法能够实现大口径平面反射镜的高精度检测。     

基于最大似然估计算法的子孔径拼接检测技术

大口径平面镜作为光学系统的重要组成部分, 其面形精度对系统成像具有重要影响。子孔径拼接检测作为大口径光学平面反射镜检测的常用手段, 子孔径拼接算法是该技术的核心。研究了平面子孔径拼接算法, 基于最大似然估计与正交化Zernike多项式拟合建立了一套合理的拼接算法与数学模型, 基于该算法模型可以有效实现对大口径平面镜的拼接检测, 同时编写了相应的拼接程序, 并利用100 mm干涉仪对120 mm的平面镜进行了拼接检测, 给出了拼接检测与全口径检测的对比结果, 对比结果表明: 拼接所得全孔径相位分布与全口径检测结果的RMS值偏差分别为0.002, 验证了算法的可靠性与准确性。     

一种降低平面子孔径拼接累积误差的方法

干涉仪参考镜面形离焦误差难以精确标定,是导致拼接累积效应、制约平面子孔径拼接系统检测精度的主要因素。推导了参考镜离焦与拼接累积误差、拼接次数间的定量表达式,基于该表达式在拼接过程中标定并去除参考镜离焦误差,降低拼接累积误差。对450 mm×60 mm的平面镜进行了8个子孔径的拼接检测,与大口径干涉仪检测结果比对,去除参考面离焦误差前后拼接测量误差峰谷(PV)值从λ/10减小至λ/30,有效提高了拼接测量精度。结合绝对检验技术标定参考镜高阶面形误差,验证了离焦是引起拼接误差累积的主要因素,消除参考镜高阶面形误差并不能显著提高拼接检测精度。     

大口径碳化硅反射镜面形子孔径拼接干涉检测

为了突破大口径反射镜面形检测的瓶颈,提出了子孔径拼接干涉检验方法。分析研究了子孔径拼接的基本原理与实现流程。基于三角剖分算法、最小二乘拟合和齐次坐标变换等建立了综合优化子孔径拼接数学模型。结合工程实际,规划7个子孔径完成了口径为800mm的大口径碳化硅反射镜的拼接测量,获得了全口径面形分布。利用基准靶标并基于迭代算法实现了镜面物理坐标与拼接像素坐标之间的转换,从而为大口径反射镜后续数控精确加工提供了依据。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks