多光束激光外差高精度测量玻璃厚度的方法

利用基于激光外差测量技术和激光多普勒技术的非接触式多光束激光外差测量方法,得到了光电探测器输出电流的谐波表达式.讨论了该测量方法用于玻璃厚度超精密测量的可行性及理论依据,并利用Matlab软件对不同情况进行了仿真实验.结果表明：该方法在不同入射角时测量平板玻璃厚度最大的误差为0.3%,明显比其他测量方法精度高. 关键词： 外差探测 多光束激光外差 激光多普勒技术 非接触式测量     

利用高精度时间间隔测量技术实现光速测定方法的研究

为了实现实验室环境下测定光速，采用已知长度及折射率的单模零色散光纤作为传输介质，利用高精度时间间隔测量技术测量了光在该光纤中的传输延时。经过理论推导，求出光速c与作为传输介质的光纤长度L、折射率n及光纤延时τ之间的关系式，从而通过测量得到L，n及τ的值即可计算得到真空中的光速值。与传统的利用天文法及精密仪器测量光速的方法相比，采用比较先进的高精度时间间隔测量技术可使时间分辨率达到125ps，从而在实验室环境下，利用简单仪器得到了高精度的测量结果。最终测量所得光速为299928077m/s，误差为30860m/s。     

细小管材的自动化高精度超声测量

文章介绍了高精度细管材直径和薄壁厚的超声自动测量系统,对实验结果进行了误差分析,实验结果表明系统不确定度可达±2μm。     

Gravitational equations of motion at the string scale

We consider the magnitude of string corrections to Einstein's equations to first order in the inverse string tension α′ and their importance at the “limiting” temperature implied by the exponential mass spectrum. In particular we consider both four- and ten-dimensional superstring theories with and without the inclusion of dilaton effects and the role of compactification. Cosmological applications such as inflation are also discussed. We find that a period of inflation necessarily requires a non-trivial role for the dilaton field.     

一种快速产生数字式高精度高斯噪声的新方法

伪随机噪声在信号分析和信号处理中具有重要的实用价值，高晰随机信号是一种最常用的信号形式，本文给出一种产生高斯噪声序列的新方法，利用先进的ＤＳＰ芯片编程技术，将高速产生的均匀分布噪声进行抽样变换，得到了高精度的高斯分析噪声序列，因此这种方法产生的高斯噪声统计特性好，周期长，性能稳定，符合声纳和通信等有关领域的要求，本文给出了原理分析，系统设计及实际应用结果。     

A group theoretic method for string loop diagram

The new approach to arbitrary string scattering proposed by the authors is used to compute the planar tadpole operator, including its measure, for the open bosonic string. The Virasoro gauge identities play a crucial role and are found to contain in general anomalous terms for open strings.     

Study on high-precision temperature measurement of infrared thermal imager

The objective of this paper is to improve the precision and reliability of algorithms for temperature measurement using an IRFPA. A high-precision infrared temperature measurement algorithm based on the nonlinear response of each pixel in the IRFPA is proposed. The results show that the error variance of the algorithm is about one-sixth of traditional algorithms under identical conditions.     

Capacitive position measurement for high-precision space inertial sensor

Low noise position measurement is fundamental for space inertial sensors, and at present the capacitive position sensor is widely employed for space inertial sensors. The design for the possible suppression of the front-end electric noises for a capacitive sensor is presented. A prototype capacitive sensor with 2×10⁻⁶pF/Hz1/2 at frequency above 0.04 Hz is achieved and further improvements are discussed.      

On the radial motion of quarks bound by a string

It is shown rigorously that quarks cannot move in the radial direction when they are tied together by a straight-line string and the system as a whole rotates with a nonvanishing angular velocity. This implies that in a consistent string model of hadrons the radial motion of quarks cannot be separated from the transverse string excitations.     

Creep motion of an elastic string in a random potential

We study the creep motion of an elastic string in a two-dimensional pinning landscape by means of Langevin dynamics simulations. We find that the velocity-force characteristics are well described by the creep formula predicted from phenomenological scaling arguments. We analyze the creep exponent mu and the roughness exponent zeta. Two regimes are identified: when the temperature is larger than the strength of the disorder, we find mu approximately 1/4 and zeta approximately 2/3, in agreement with the quasi-equilibrium-nucleation picture of creep motion; on the contrary, when lowering the temperature enough, the values of mu and zeta increase, showing a strong violation of the latter picture.     

Pregeometrical string field theory: Creation of space-time and motion

A space-time-metric-independent and gauge-invariant formulation of closed-string field theory is proposed. The action contains no kinetic term and consists solely of a cubic term in the string field. The kinetic term can be generated through the condensation of an infinitesimally small string.     

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引进了美国GAMMA公司的高精度数字式可调标准光源RS-5B,并对其性能参数进行了测试。结果表明,该光源光强空间分布非常稳定,在光强大于0.001μW•cm-2时,复位性优于1%;在光强大于0.01μW•cm-2时,稳定性优于0.5%。其输出光强与标称值呈线性分布关系。这些优良的参数和特性满足聚变物理标定研究中对标定源的需求,为物理实验数据分析和计算模拟提供了条件。     

Calibration of geometrical systematic error in high-precision spherical surface measurement

Geometric aberrations in interferometric testing system can significantly influence the measurement results in the case of high-numerical-aperture test spherical surface, in which obvious high-order aberrations introduced by wavefront defocus could be observed and they cannot be removed with the traditional calibration method. A technique based on the rigorous model for the analysis of geometric aberrations introduced by wavefront tilt and defocus, is presented for the calibration of the corresponding geometrical systematic error. The calibration method can be carried out either with or without a prior knowledge of the spherical surface under test. The feasibility of the proposed method has been demonstrated by computer simulation, and the residual error less than 0.001λ is obtained. Experimental validation is carried out by testing a high-numerical-aperture spherical surface with the ZYGO interferometer, and an accuracy RMS about 0.003λ with the proposed calibration technique is achieved. The effect of geometric aberrations on the measurement is discussed in detail. The proposed calibration method provides a feasible way to lower the requirement on the adjusting precision of mechanical device, and is of great practicality for the high-precision measurement of high-numerical-aperture spherical surface.     

A high-precision measurement of the stark shift of the sodium D1-line

Using laser—atomic-beam spectroscopy and a special field arrangement the Stark shift of the sodium D₁-line was determined to be 48.986 (112) kHz (kV/cm)^?2. Using the literature value for the scalar polarizability of $\text{2}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, 39.7 (8) kHz (kV/cm)^?2, the polarizability of $\text{2}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was derived to be 88.69 (81) kHz (kV/cm)^?2.     

General method for determining the sensor readings of motion measurement systems by using skew-ray tracing method

High-accuracy laser-based optoelectronic motion- and position-measuring systems typically utilize light rays that travel from one optical boundary surface to another to perform motion and/or position measurements. It is not a simple task to accurately determine the equations of these sensor readings in terms of positional/angular motions. This problem is addressed in this paper by application of the analytic skew-ray tracing methodology as computed by the finite-difference methodology. An illustrative example of a motion-measurement system and comparison of the position-sensing detector (PSD) readings are given to validate the proposed methodology. It is shown that the proposed methodology can provide accurate expressions of PSD readings. It is also shown that the performance of a corner-cube retro-reflector is better than a cat's eye retro-reflector in positional/angular motion measurement systems.     

低频响及低采样频率下用布朗运动分析法测量光阱刚度

布朗运动法测量光阱刚度因其简便易行而成为光镊系统参数测量的一种常用的方法，但是由于在低频响或低采样频率时测量结果误差很大，所以主要用在频响及采样频率较高的情况下.将在功率谱分析及实验的基础上，讨论如何在低频响及低采样频率下，用布朗运动法测量光阱刚度. 关键词： 布朗运动 光阱刚度 光镊 功率谱