分光计调整的成像演示

介绍一种演示分光计调整的方法，可以在屏幕上演示分光计调整过程反射十字像的移动和成像系统的结构。     

分光计调节新方法

1 引言 高等学校开设的《普通物理实验》，用分光计测棱镜折射率和光波波长．学生对分光计的调节具有一定的难度，通过望远镜寻找平面半反射镜反射的绿色十字叉丝像是难点．由于刚开始调节时，载物台的转轴与望远镜轴线偏离垂直状态较远，反射镜反射的绿色十字叉丝像一般会在望远镜视场之外，因而人眼观察不到．本人根据多年的实践经验得出，通过用平行光管狭缝的透射像作辅助标志物，使调节过程中寻找反射绿十字叉丝像变得非常简单，从而使分光计的调节变得容易．     

分光计快速调节方法探讨

在分光计调节实验中,调节望远镜光轴与分光计中心轴相互正交是最关键也是最困难的一步,针对实验中经常出现的观察不到"十"字叉丝反射像的问题,本文提出了一个新的简单有效的调整方法——调节望远镜俯仰螺丝的同时不断地转动游标盘(连同载物台),在此过程中用眼睛一直观察望远镜视场是否有绿色十字像出现(简称"一看二动法")."一看二动法"快速找到两个绿色十字像后,再利用"减半逐步逼近法"进行细调,从而大大地提高了课堂的实验教学效率.     

分光计调节难点探讨

分光计是大学物理实验中常用的一种仪器。由于其调节内容较多,如何快速地调出分光计中的两面的反射十字像是分光计实验中的难点。本就调节中的这一难点进行了分析,并提出几种适当的调节办法。     

快速粗调分光计的小窍门

在使用分光计的实验中,首先需要对分光计进行粗调,然后用各半调节法细调.粗调的目的是能够在镜中观察到由载物台上小平面镜的两个面反射回来的绿"十字",以供进一步细调.但是,对于初次使用分光计或不经常使用分光计的实验者并不容易在较短的时间内就完成粗调,有时甚至要花费相当长时间.为了解决这一问题,现介绍如下小窍门.     

改进反射法测三棱镜顶角实验的思考

反射法测三棱镜顶角要求望远镜、平行光管和三棱镜都要满足测试要求，对分光计调节的要求更全面。镜外辅助粗调法常被用于解决分光计粗调不理想的情况。针对该方法不易掌握的问题，通过分析平面镜中望远镜反射像的成像规律，确定了镜外辅助法调节良好，即达到最佳容错位置的标志现象，即从望远镜外观察到的绿色十字光源与望远镜分划板上的水平直径叉丝位于同一水平面上。三棱镜放置位置是影响狭缝反射像观察的重要因素。三棱镜最佳的放置位置为待测顶角A放到载物台中心，确保可以观察到AB和AC两个光学面反射的狭缝像。     

分光计中各种反射像形成的原因及其分析

分光计实验中需要利用反射像来调整仪器和测量角度，在实验中经常会观察到明亮程度不同而形成方法各异的反射像。对这些反射像形成的原因进行分析有助于了解分光计的工作原理和调节方法，缩短调整时间提高工作效率。     

分光计的分别调节法

本文介绍了一种调节分光计的独特方法。采用该法,能顺利找到十字叉丝反射像,且能解决因调整所用的平面反射镜与其底面垂度不好而带来的问题,使分光计快速调好。     

分光计快速调节法——跟踪法剖析

在分光计实验中，调节望远镜光轴与分光计中心轴相互垂直的过程是实验中花费时间较长、出现问题较多的一个环节，利用望远镜跟踪望远镜与平面镜一侧达到自准的十字丝像，并逐步调节以达到望远镜与平面镜另一侧也自准的跟踪法，能够快速完成望远镜光轴与分光计中心轴垂直的调节过程。     

分光计实验中望远镜的快速调节方法——台先镜后法

在分光计实验中,调整望远镜光轴与分光计主轴大致垂直是最关键、最难调的一步．实验中容易观察到平面镜一个面反射回的“十”字像,却较难调出两个面反射回的“十”字像．本文利用光路图进行了分析,提出了一个快速、有效的调整方法——台先镜后法．     

A new four-dimensional chaotic system

A new four-dimensional chaotic system with a linear term and a 3-term cross product is reported.Some interesting figures of the system corresponding different parameters show rich dynamical structures.     

三角变形椭圆截面环电流器的平衡理论和绝热压缩理论

本文研究了带有滴形截面的托卡马克磁流体平衡问题,给出了靠外线圈维持这种平衡所需的电流分布和整个自洽平衡解。重点研究了对这样的位形进行绝热压缩加热等离子体问题,给出了在压缩过程中整个平衡位形随时间的演化。结果表明具有滴形截面的等离子体平衡位形在绝热压缩过程中是能够由初态连续过渡到终态的。 关键词：     

Lissajous figures in the application of micro-vibration measurement

Based on Michelson interferometer and phase generated carrier (PGC) homodyne demodulation technique, an optical interferometer system is built, and a novel method using the central angles of Lissajous figures to measure micro-vibration displacement is proposed. The Lissajous figures are obtained by synthesizing two interferometric signals that their vibration directions are orthogonal and their intensities are equal. Through theoretical analysis, software simulation and experimental test, it is concluded that the central angles of Lissajous figures have a linear relationship with the phase modulation coefficients and the micro-vibration displacements when the phase modulation coefficients are small. So the micro-vibration displacements can be directly obtained by measuring the central angles of Lissajous figures. The method is simple and convenient. The experimental results indicate that the micro-vibration displacements measuring range can reach 5-775 nm, with a resolution of about 5 nm.     

Relativistic coulomb excitation

Coulomb excitation of both target and projectile in relativistic heavy ion collisions is evaluated including the lowest order correction for the deviation from a straight line trajectory. Explicit results for differential and total cross sections are given in the form of tables and figures.     

平面上方分层小球的光散射计算

本文基于扩展的Mie理论方法求解平面上方分层小球的散射问题。通过建立小球和平面的模型,解决小球和平面的边界条件问题,并利用矢量波函数展开的方法求得了散射场。强调了小球与表面的相互作用。利用Mie理论方法得到了分层小球的散射场系数,通过计算平面上小球的散射模型,得到了平面上分层小球的散射场分布。结论给出了分层介质小球的微分散射截面图。     

Cross sections of the interactions of4He nuclei with protons at 8·6 and 13·6 GeV/c

⁴He-p collisions at two values of⁴He momenta-8·6 GeV/c and 13·6 GeV/c — have been studied using the one-metre JINR hydrogen bubble chamber. Total, elastic and topological cross sections have been measured. The results are in agreement with other published data. The elastic differential cross section was compared with the predictions of the Glauber model formalism.Dedicated to Academician Václav Votruba on ths occasion of his eightieth birthday.We would like to thank Mrs. M. Stehlíková for drawing the figures.     

Rabi and Ramsey interrogations of metastable beams

The interaction between a metastable atomic beam and a standing-wave radiation field is analyzed taking into account the effects of the natural decay between the interrogation zones and in the detection region; moreover the problem is concerned with atomic beams with cross section much wider than the radiation wavelength (multiwavelength cross section). The analysis is carried out in the density matrix formalism and numerical results obtained refer to the new frequency standards based on fine structure transitions within the Mg and Ca metastable triplets.Rabi and Ramsey techniques have been considered and the interesting figures of signal-to-background and signal-to-noise ratios, linewidth and saturation field have been evaluated assuming a Maxwellian velocity distribution and taking into account the detection process.     

Theoretical examination of ultrasonic pole figures via comparison with the results analyzed by finite element polycrystal model

The ultrasonic wave velocities in a polycrystalline aggregate are sensitively influenced by texture development due to plastic deformation. According to Sayer's model, it is possible to construct ultrasonic pole figures via the crystallite orientation distribution function (CODF), which can be calculated by using ultrasonic wave velocities. In the previous papers, the theoretical modeling to simulate ultrasonic wave velocities propagating in solid materials under plastic deformation has been proposed by the authors and proved to be a good agreement with experimental results. Generally, wave velocities are dependent upon the propagating wave frequency; hence to evaluate texture development via ultrasonic pole figures it is necessary to examine an influence of frequency dependence on the ultrasonic wave velocities. In the present paper, the proposed theoretical modeling is applied to the texture characterization in polycrystalline aggregates of FCC metals under various plastic strain histories via ultrasonic pole figures, and also the frequency dependence is examined by using Granato-Lücke's dislocation strings model. Then the simulated ultrasonic pole figures are compared with the pole figures analyzed by the finite element polycrystal model (FEPM). The good qualitative agreement between both results suggests the sufficient accuracy of our proposed theoretical modeling.     

Exact solution of Maxwell's equations for optical interactions with a macroscopic random medium: addendum

This Addendum provides a revised set of figures containing converged numerical data for total scattering cross section (TSCS), replacing the figures in our recent publication [Opt. Lett. 29, 1393 (2004)]. Due to the use of an overly large time step, our original TSCS data exhibited a systematic, nonphysical diminution above 150 THz for all cases studied. We have determined that numerical convergence in the temporal sense for the pseudospectral time-domain (PSTD) algorithm employed previously requires limiting the time step to no more than 1/60th of the sinusoidal period at the maximum frequency of interest, which in the previous case was 300 THz. This is an important point that we hereby report to future users of PSTD simulations in electrodynamics and optics. Note that all our original conclusions remain valid.     

Neutrino Production via e-e+ Collision at Z-Boson Peak

The production of the three normal neutrinos via e^-e⁺ collision at Z-boson peak (neutrino production in a Z-factory) is investigated thoroughly. The differences of v_e-pair production from v_μ-pair and v_τ-pair production are presented in various aspects. Namely the total cross sections, relevant differential cross sections and the forward-backward asymmetry etc. for these neutrinos are presented in terms of figures as well as numerical tables. The restriction on the room for the mixing of the three species of light neutrinos with possible externals (heavy neutral leptons and/or sterile neutrinos) from refined measurements of the invisible width of Z-boson is discussed.