测量长焦距反射镜的曲率半径

测量长距离反射镜的曲率半径，不论是在验证近轴光线球面镜的成象公式还是在实践上都有很重要的意义。但是如果反射镜表面的曲率半径Ｒ＞５ｍ时，验证和测量都是相当复杂的问题。本文给出了一种很简便的测定Ｒ的方法，在曲率半径是１０ｍ左右时的测量误差是１％。     

A novel compensation method for the measurement of radius of curvature

A test method for spherical mirrors with super-long radius of curvature that only one compensator is employed to measure the radii of curvature of both concave and convex mirrors is presented. With this testing system, the surface figure and radius of curvature of spherical mirrors can be measured simultaneously. Using the ABCD matrix method, a precise formula for radius of curvature calculation is deduced. Experimental results show that the relative measurement error of this method is less than 4.2×10⁻⁴.     

Seya-Namioka单色仪中光栅曲率半径误差的影响及补偿

Seya-Namioka光栅制作过程中的曲率半径误差会引起离焦像差,该像差会对光栅单色仪的光谱性能造成极大的影响。本文基于光线追迹理论,模拟分析了曲率半径误差对Seya-Namioka光栅的具体影响。分析结果表明,出入臂长度对曲率半径误差有很好的补偿作用,通过调整出入臂长度曲率半径误差的容许范围可增大到2 mm左右。总调整量不变的情况下,任意改变出入臂的长度,补偿效果相似。随着误差的增加需要调整的出入臂长度值变大,过大的误差使用出入臂长度无法进行补偿;出入臂夹角仅能对正向曲率半径误差进行补偿,且补偿所需调整角过大,影响单色仪的结构设计,该方法并不实用。结果可为单色仪的设计和使用提供理论参考。     

双凹厚透镜曲率半径和折射率的测定

观察双凹厚透镜的球面反射成像,利用这一实验现象结合物像公式测定双凹厚透镜前后表面的曲率半径和折射率。利用两次球面反射成像可求出双凹厚透镜的曲率半径,两种方法可比较。对于薄透镜,这种方法可以修正在实际测量中忽略透镜厚度所产生的误差。     

Positive Tolman length in a lattice gas with three-body interactions

We present a new method to determine the curvature dependence of the interface tension between coexisting phases in a finite volume from free energies obtained by Monte Carlo simulations. For the example of a lattice gas on a 3D fcc lattice with nearest neighbor three-body interactions, we demonstrate how to calculate the equimolar radius R(e) as well as the radius R(s) of the surface of tension and thus the Tolman length δ(R(s))=R(e)-R(s). Within the physically relevant range of radii, δ(R(s)) shows a pronounced R(s) dependence, such that the simple Tolman parametrization for the interface tension is refutable. For the present model, extrapolation of δ(R(s)) to R(s)→∞ by various methods clearly indicates a positive limiting value.     

偏振成像在光学曲率半径测量中的应用

为了保证整个光学系统的质量,对光学曲率半径的准确测量与检验至关重要.本文将机械球径仪法与光学投影法结合,采用光电图像法对矢高进行判读,经计算可以间接测得曲率半径,具体分析了被测元件边缘特征的准确性对矢高及曲率半径测量精度的影响.本文分别采用偏振成像与普通成像的方法进行了测量与对比,发现偏振图像具有更好的边缘细节特征,矢...     

(O)ffner展宽器曲面镜误差对输出脉冲对比度的影响

在(O)ffner展宽器的设计研究中,对曲面镜曲率半径的误差研究非常重要,它直接影响输出脉冲的质量.因此有必要分析(O)ffner展宽器中曲面镜曲率半径的误差对输出脉冲对比度的影响.参考(O)ffner展宽器的光线追迹模型,建立了(O)ffner展宽器中曲面镜曲率半径存在误差时的光线追迹模型;根据建立的模型.详细分析了曲面镜曲率半径的误差对输出脉冲质量的影响;发现在目前曲面镜曲率半径的加上误差在0.2%～0.5%的情况下,完全可以满足神光Ⅱ拍瓦激光装置中对展宽器的要求;同时发现如果曲面镜曲率半径存在误差时,应该尽量使两曲面镜之间的距离保持为凹面反射镜曲率半径的一半,而不是使两曲面镜保持同心.     

双凸厚透镜曲率半径及焦距的测定探讨

利用双凸厚透镜的折反折成像,测定已知折射率的厚透镜前后表面的曲率半径及焦距。此方法可以修正测量透镜焦距忽略透镜厚度所产生的误差。     

Calculation of curvature dependent surface plasmon resonance in gold nanospheroid and nanoshell

In this paper, theoretical calculations based on dipole-limit are performed to investigate the effects of curvature on the surface plasmon resonance (SPR) properties of nanometer size gold spheroid and shell. By comparing the aspect ratio with the shell thickness, we demonstrated that the curvature radius is a common better factor that can be used to predict the SPR wavelength and shift fashion. For nanospheroid, increasing the ratio of curvature radius corresponding to the climaxes leads to an increase in the ratio of SPR wavelength, whereas increasing the ratio of curvature radius of outer and inner surface in nanoshell leads to an decrease in the ratio of SPR wavelength. As a morphologic factor, curvature radius plays an important role in affecting the distribution of electron density, and consequently controlling the SPR frequency.     

Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

In view of the continued disputes on the fundamental question of whether the surface tension of a vapour bubble in liquid argon increases,or decreases,or remains unchanged with the increase of curvature radius,a cylindrical vapour bubble of argon is studied by molecular dynamics simulation in this paper instead of spherical vapour bubble so as to reduce the statistical error.So far,the surface tension of the cylindrical vapour bubble has not been studied by molecular dynamics simulation in the literature.Our results show that the surface tension decreases with radius increasing.By fitting the Tolman equation with our data,the Tolman length δ = -0.6225 sigma is given under cut-off radius 2.5σ,where σ = 0.3405 nm is the diameter of an argon atom.The Tolman length of Ar being negative is affirmed and the Tolman length of Ar being approximately zero given in the literature is negated,and it is pointed out that this error is attributed to the application of the inapplicable empirical equation of state and the neglect of the difference between surface tension and an equimolar surface.     

基于白光干涉的光学球面半径测量研究

光学球面曲率半径是决定光学球面光学特性的重要参量,通过测量光学球面的曲率半径，可以审核光学元件设计制造质量。在基于白光干涉理论基础上，将莫尔光栅位移测量系统及CCD数字图像采集处理系统集成到迈克尔逊干涉仪上，利用CCD数字图像处理技术，构建了光学球面曲率半径自动测量系统。该测量系统对于大曲率半径的光学球面测量精度较高；对于半径R＝71.2037mm的光学球面,其测量标准误差σR＝0.4723mm。实验结果表明：设计的光学球面自动测量系统可以对大曲率半径光学球面实现高精度测量。     

部分相干平顶光束通过湍流大气传输的等效曲率半径

推导出了部分相干平顶光束在湍流大气中传输的等效曲率半径的解析表达式,详细地研究了湍流对其等效曲率半径的影响.研究表明,湍流使得等效曲率半径R减小,但是只有当湍流足够强时等效曲率半径极小值出现的位置z_min才会改变.在弱湍流中,R随着光束相干长度β的增大而增大;但是在强湍流中,R随着β的增大而减小.R随着光束阶数M(N)的增大而缓慢减小.若β越大、 关键词： 等效曲率半径 湍流 部分相干平顶光束     

一种精确测量光学球面曲率半径的方法

在简要总结各种检测光学球面曲率半径方法优缺点的基础上,提出了利用激光跟踪仪和激光干涉仪测量光学球面曲率半径的新方法。首先,通过激光跟踪仪精确定位测量干涉仪出射球面波前的焦点和待测球面镜的曲率中心点坐标,再调整待测球面镜与干涉仪的相对位置,使待测球面镜达到零条纹干涉状态,用激光跟踪仪测定此时待测球面镜上多点的位置坐标,通过计算分析即可得到待测球面镜的曲率半径。研究和分析了这种测量光学球面曲率半径方法的基本原理,并提出了针对凸球面镜曲率半径的多区域测定平均综合优化的方法。结合实例对一口径为400mm的球面透镜进行了曲率半径的测量,测量得到其两面曲率半径分别为1022.283mm(凸面)和4069.568mm(凹面),并将该透镜进行了轮廓法测量对比,其相对误差都小于0.05%。     

激光等倾干涉法

本文介绍一种新的基于两点光源干涉原理的精确检测透镜中心偏的方法。利用由静止参考面和位于空气轴承转台上的被检透镜表面之间产生的非定域干涉条纹,可以把透镜的面倾角误差大大放大并加以检测。这种方法与现有的透镜中心偏检测方法相比具有精度高、操作简便、并与透镜形状无关等明显优点。理论与实践证明,如果参考面的曲率半径和参考面与被检面之间的空气间隔选得合适,那么即使用肉眼也能检测出约1″大小的透镜面倾角误差。     

大口径天文薄镜面磨制试验

介绍了采用薄镜面主动支撑技术来加工大口径天文薄镜面的试验情况。试验镜为一弯月型球面反射镜．直径为Ф1035mm,镜面曲率半径为3220mm,径厚比约为40：1。在磨制过程中,有55个分离支撑点支撑存镜子背面。支撑点的位置与支撑力的大小通过有限元分析计算确定,其中3个为固定支撑点．另外52个为主动支撑点。每个支撑点位置设置了力促动器,调节力促动器加力的大小。可以主动改正镜面的低频误差。加工后最后达到的面形精度：λ=632．8nm,面形误差(RMS)小于等于λ／21．5,局部高频误差(RMS)小于等于λ／23。试验证明所采用的方法适合于大口径天文薄镜面的加工。     

On controlling the surface curvature of diffraction components

The possibility of interactively controlling the surface curvature of a single-crystal Si(100) plate used as a diffraction element is investigated. The initial component-surface profile is specified by the substrate shape, parameters of the adhesive, and the temperature of its adhesion to the substrate. The results of calculating the changes in surface profile and its curvature radius are presented.     

Size-dependent surface tension of cylindrical nano-bubble in liquid Ar

In view of the continued disputes on the fundamental question whether the surface tension of vapour bubble in liquid argon increases, or decreases, or remains unchanged with the increase of curvature radius, the cylindrical vapour bubble of argon is studied by molecular dynamics simulation in this paper instead of spherical vapour bubble so as to reduce the statistical error. So far the surface tension of the cylindrical vapour bubble has not been studied by molecular dynamics simulation in the literature. Our results show that the surface tension decreases with radius increasing. By fitting Tolman equation with our data, the Tolman length δ =-0.6225 sigma is given under cut-off radius 2.5σ, where σ =0.3405 nm is the diameter of argon atom. The Tolman length of Ar being negative is affirmed and the Tolman length of Ar being approximately zero given in the literature is negated, and it is pointed that this error is attributed to the application of the inapplicable empirical equation of state and the neglect of the difference between surface of tension and equimolar surface.     

Reducing the line curvature error of mechanically ruled gratings by interferometric control

Line curvature error greatly influences the quality of the diffraction wave fronts of machine-ruling gratings. To reduce the line curvature error, we propose a correction method that uses interferometric control. This method uses diffraction wave fronts of symmetrical orders to compute the mean line curvature error of the ruled grating, taking the mean line curvature error as the system line curvature error. To minimize the line curvature error of the grating, a dual-frequency laser interferometer is used as a real-time position feedback for the grating ruling stage, along with using a piezoelectric actuator to adjust the stage positioning to compensate the line curvature error. Our experiments show that the proposed method effectively reduced the peak-to-valley value of the line curvature error, improving the quality of the grating diffraction wave front.     

大口径平背形主镜支撑方式的选择

支撑方式对主镜面形的变化有十分重要的影响。为了使主镜的安装支撑既能保证面形变化最小,又能保证在不同仰角时位置不变动,需要对主镜的支撑方式进行分析和选择。通过对一个口径为600mm、中心孔径为200mm、光学表面曲率半径为2130mm的实体镜在各种支撑情况下的变形大小进行分析,并综合考虑加工、一阶共振频率及工作时的旋转因素后,最终确定了一种满足设计要求的优选支撑方案。     

Fabrication of 15 nm curvature radius polymer tip probe on an optical fiber via two-photon polymerization and O2-plasma ashing

Polymer tips with 15 nm curvature radius apexes that are capable of scanning the surface of a sample have been fabricated on the surface of an optical fiber using two-photon photopolymerization (TPP) and O₂-plasma ashing with a SCR500 resin. First, the parent conical polymer tip with a 125 nm curvature radius apex was fabricated via TPP using a continuous scanning method and the accumulation of circular layers. Next, the tip was sharpened using an O₂-plasma ashing process with high reproducibility. As a result, the apex radius of curvature had a maximum reduction to 15 nm. In order to evaluate the performance of the 15 nm curvature radius polymer tip, a 30 nm thick gold layer with holes of 250 nm radius and a single layer of polystyrene beads with a 350 nm radius were imaged using a tuning-fork-based atomic force microscope. The topographic images obtained by the 15 nm polymer tip were improved in width and depth compared with those obtained by the 125 nm polymer tip due to the reduction of the imaging artifacts. This method can also be commonly used to reduce the radius of curvature of the polymer tip in order to achieve more accurate imaging.