激光散斑图样法随机相移器在全息照相中的应用

本文叙述了制作随机相移器的三种不同方法,着重论述了用随机分布激光散斑照相漂白法制作的随机相移器在全息存贮中的应用;给出和比较了它们的付立叶频谱分布及在全息存贮中用于改善像质的实验结果。     

一种两步相移任意步距相位轮廓测量技术研究

对传统相移轮廓测量技术进行研究,提出基于Gram-Schmidt正交化法的两步相移任意步距相位轮廓测量技术并应用到三维轮廓测量中。由CCD采集两幅投影光栅图,且两幅图像之间的相移值不需要事先给定,可以随机取任意值;在保证精度的前提下,该技术只需两幅变形光栅图,同时无需对相移器的相移精度作要求。实验表明:与现有的几种相移轮廓术比较,提出的两步相移任意步距相位轮廓测量技术可以快速地恢复待测相位,且获取待测物体的三维数据精度较高,具有较强的适用性。     

改善付里叶变换全息图像质的几种方法

本文主要叙述了在全息存贮中改善付里叶变换全息图像质的方法,包括离焦法和随机相移器法。分析了全息图尺寸及其记录的空间频带宽度与离焦量的关系;给出和比较了不同离焦量情况下的以及离焦法与随机相移器法的实验结果。实验和分析表明,选择适当的光束衡量比和曝光量,并将离焦法与随机相移器方法结合用于全息存贮,可以得到较高的再现像衍射效率和信噪比(SNR)。最后还给出了用稀释显影加漂白的方法可进一步提高衍射效率的实验结果。     

一种高精度相移器的制作与标定

介绍相移的引入和计算机控制相移器原理及实现方案,制作了一个稳定且精度高的直流高压电源,并在此基础上设计完成一台稳定性高、动态范围大、精度高、具有较高自动化程度的相移器。建立了一套相移器标定方法,并根据设计的标定装置进行了准确标定。定性定量分析了产生误差的原因及大小。     

高频相移器测试方法研究

为解决高频相移器的溯源问题,在介绍相移器工作原理基础上,分析高频相移器的相移准确度、绝对相位测量准确度、插入损耗和电压驻波比等性能指标。利用网络分析仪、校准件、低失真信号发生器和高准确度相位计搭建相移器的测试平台,阐述相移器的基本校准方法和校准步骤。通过建立不确定度传播率的数学模型,分析相移器的相移参数测量的不确定度分量来源,从而对被测相移器核心参数的准确度进行不确定度分析和评估。实现高准确度相移器的溯源方法,提高信号相移控制的准确度。     

一种新型量化混沌序列的统计特性研究

提出了一种多值量化器，并对一维无限折叠混沌映射所产生的多值量化序列的统计特性与混沌映射和量化器参数的关系进行了研究。理论分析和统计检验表明，选择适当的参数可使量化序列接近于独立同分布序列。该多值序列发生器还具有结构简单、实现效率高等优点。因此，它可用于产生混沌扩谱序列和混沌密钥流序列。     

用于KrF准分子激光光刻的衰减相移掩模

讨论了相移掩模提高光刻分辨力的基本原理,提出了一种抗蚀剂相移器制作衰减相移掩模的新方法,利用自行设计、建立的KrF准分子激光投影光刻实验曝光系统进行了实验研究,给出了实验结果,并与传统光刻方法作了比较.     

用于KrF准分子激光光刻的三相移掩模

讨论了相移掩模提高光刻分辨力的基本原理,提出了一种抗蚀剂相移器制作衰减相移掩模的新方法,利用自行设计、建立的ＫｒＦ准分子激光投影光刻实验曝光系统进行了实验研究,给出了实验结果,并与传统光刻方法作了比较。     

随机相移误差的Lissajous标定与校正

将Lissajous标定技术应用到相移干涉测量的相移算法(PSA)中,提出一种基于Lissajous标定技术的随机相移误差校正算法。该算法不需要计算各帧干涉图之间的实际相移量,直接用Lissajous标定和椭圆拟合的方法计算相移算法的相位提取误差(包括离焦、偏倚、相移量偏差)然后进行校正。数值模拟结果表明:该算法不需要迭代运算就能从大于3帧的带有随机相移误差的干涉图中有效恢复出正确的相位信息,运算时间少,计算精度高并且适合于所有的相移算法。实验结果表明:基于Lissajous标定技术的随机相移误差校正算法与现有的迭代随机相移算法(AIA)精度相当,但计算速度得到明显提升。     

微波双通道相移测量中失配误差的对消

本文提出一种对消微波双通道相移测量中失配误差的方法,可用于精密相位计的比对和高精度相移器的研制。论述了此法的理论和测量步骤,在X波段进行了实验验证,获得良好的结果。     

Ballistic Particles in Helium Systems

Ballistic motion of (quasi-)particles in helium systems with quantized and quasi-continuous spectrum is discussed under conditions when the mean free path is restricted by scattering on random surface inhomogeneities. The transport equation is derived for particles with arbitrary form of energy spectrum and without model assumptions on the structure of surface scattering operator. The results can be applied to quasiparticles in liquid helium systems with quadratic and linear spectra, spectrum with a gap, etc. The transport equation is relatively simple except for the case when the distance between quantized energy levels is comparable to the surface collision frequency. In three limiting cases the diffusion coefficient is calculated analytically for arbitrary correlations of surface inhomogeneities, and elsewhere - numerically for Gaussian correlations. The interwall correlation of surface inhomogeneities affects particle diffusion in a non-trivial way; sometimes, the effect of interwall correlations persists even in the quasiclassical limit.     

随机噪声对伺服系统跟踪精度的影响

文中以经典的三闭环伺服系统为研究对象,较为详细的论述了测流噪声、测速噪声、测位噪声以及力矩扰动噪声对跟踪精度的影响;推导了四种随机噪声与跟踪精度之间的传递函数;通过对传递函数的变换,得出了系统带宽及校正环节与随机噪声关系,为传感器选择、测量数据处理和校正环节的参数整定提供了参考;给出了随机噪声服从高斯分布情况下的仿真实验,针对随机噪声与跟踪精度的幅频特性,提出了一种分段线性化计算平均衰减倍数的方法.通过这种方法计算了四种随机噪声对跟踪精度的量化影响,并与仿真结果进行了比较,结果表明,这种分段线性化方法是正确可行的.最后,给出了四种噪声同时作用于伺服系统时的计算结果和仿真实验结果,得出了同样的结论.     

Recursive Estimation of the Mean Value of a Random Variable Using Quantized Data

Previously published methods and results for fast recursive estimation of the mean value of a continuous random variable are extended to the case of a random signal quantized by an equi-interval A/D converter.     

Dependence of Quantized Hall Effect Breakdown Voltage on Magnetic Field and Current

When large currents are passed through a high-quality quantized Hall resistance device the voltage drop along the device is observed to assume discrete, quantized states if the voltage is plotted versus the magnetic field. These quantized dissipative voltage states are interpreted as occurring when electrons are excited to higher Landau levels and then return to the original Landau level. The quantization is found to be, in general, both a function of magnetic field and current. Consequently, it can be more difficult to verify and determine dissipative voltage quantization than previously suspected.     

Full Biot-Savart Numerical Simulation of Vortices in He II

No Heading We present the results of numerical simulation for stochastic dynamics of quantized vortex filaments in HeII. Unlike many previous similar investigations, we performed calculations on base of the full Biot-Savart law. We also use a new algorithm for reconnection processes, which is based on considerations of crossing lines. In addition we introduce the random forces stirring the system. This Langevin statement of problem enables to control various types of random action. In the present simulations we take while noise as a random force. We observe that the stationary state of vortex tangle is strongly nonuniform and fluctuating, with knots suddenly appearing and disappearing, this pattern resembles the famous intermittency effect. We also present calculations of some properties of a vortex tangle (VT) such as the total length, the distribution of the length of loops, and the energy spectrum.PACS numbers: 47.32.Cc, 67.40.Vs, 05.40.-a     

SI value of quantized Hall resistance based on ETL's calculablecapacitor

The SI value of the quantized Hall resistance based on Electrotechnical Laboratory's (ETL) calculable capacitor is presented. Some improvements for previous measurement systems were made and some of the measurement techniques were changed. Based on measurements of ETL, the value of h/e² is estimated to be 25,812.8064 Ω_SI with a systematic uncertainty of 0.24-p.p.m. root-sum-square (r.s.s.) and a random error of 0.11-p.p.m. at one standard deviation (1σ)     

Calculating the Effects of Longitudinal Resistance in Multi-Series-Connected Quantum Hall Effect Devices

Many ac quantized Hall resistance experiments have measured significant values of ac longitudinal resistances under temperature and magnetic field conditions in which the dc longitudinal resistance values were negligible. We investigate the effect of non-vanishing ac longitudinal resistances on measurements of the quantized Hall resistances by analyzing equivalent circuits of quantized Hall effect resistors. These circuits are based on ones reported previously for dc quantized Hall resistors, but use additional resistors to represent longitudinal resistances. For simplification, no capacitances or inductances are included in the circuits. The analysis is performed for many combinations of multi-series connections to quantum Hall effect devices. The exact algebraic solutions for the quantized Hall resistances under these conditions of finite ac longitudinal resistances provide corrections to the measured quantized Hall resistances, but these corrections do not account for the frequency dependences of the ac quantized Hall resistances reported in the literature.     

Error reduction of quantized kinoforms by means of increasing the kinoform size

There are two kinds of method that utilize the redundancy in kinoform domains for reducing the reconstruction errors of quantized kinoforms. One is the iterative-dummy area (IDA) method, which increases the kinoform size indirectly by the addition of a dummy area to the desired image. The other is the interlacing technique (IT), which increases the kinoform size directly by the interlacing of a number of subkinoforms whose sizes are the same as the desired image. We compare the error reduction of quantized kinoforms between these two methods. Simulation results show that reconstruction errors from the IT method can be reduced further and faster than those from the IDA method when the kinoform size is increased to larger than 4 x 4 times the size of the desired image.     

Noise Parameter Estimation From Quantized Data

In this paper, the parametric estimation of the variance of white Gaussian noise is considered when available data are obtained from a quantized noisy stimulus. The Crameacuter-Rao lower bound is derived, and the statistical efficiency of a maximum-likelihood parametric estimator is discussed, along with the estimation algorithm proposed in IEEE Standard 1241     

Shaft encoder characterization via theoretical model ofdifferentiator with both differential and integral nonlinearities

A model of an incremental shaft encoder is developed to facilitate sensor characterization. The model is obtained through derivation of a new mathematical formula for the spectral characteristics of the error which accrues when a sampled, nominally constant-rate signal is uniformly quantized, having been subject to both differential and integral nonlinearities. The spectrum of the error in the rate estimate generated when a digital differentiator is applied to such a signal is shown to be of particular importance. Subsequent sensor characterization involves some basic signal processing of a set of sampled sensor outputs, obtained when the encoder rotates at an almost uniform rate, followed by a simple curve-fitting procedure using the formula for estimated rate error. Both computer-generated, finite-length data sets and experimental data derived from encoder-based shaft velocity measurements are utilized to verify the theoretical model. The methodology of the mathematical analysis is applicable to other digital sensors and to a more general class of systems; such as data converters, which involve the digital differentiation of quantized, noise-affected signals. The paper illustrates how the combined influence of quantization error and of additional sources of noise can be described in an analytical, but applicable, manner