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%。     

郎奇法检测大口径光学非球面镜

提出了一种用朗奇法定量检测大口径非球面的新技术。主要以大口径非球面镜的加工表面为研究对象,设计了大口径非球面检测系统,该系统由CCD摄像机、He-Ne激光器、郎奇光栅、微型计算机等组成。并利用大口径非球面检测系统对一个顶点曲率半径为1638．69mm,被测曲面半通光口径为315mm的光学元件的面形进行了实际测量,给出了光学元件标准偏差和峰谷值测量结果。最后对测量结果进行了讨论。研究结果表明：基于郎奇法的几何原理,利用CCD摄像系统定量检测大口径非球面的方法具有较高的精度。     

激光差动共焦曲率半径测量不确定度评定

曲率半径是球面光学元件中的重要参数之一,曲率半径的高精度测量已经成为光学元件使用与加工中的一个关键问题。提出了基于差动共焦法的曲率半径测量方法,研制了1套激光差动共焦曲率半径测量系统,并对2组曲率半径测量结果进行不确定度评定。结果表明,2组曲率半径的测量值均与标称值吻合,其相对误差为0001 15%,两组测量数据的标准不确定度均优于3211 11×10-4 mm。     

激光差动共焦曲率半径测量不确定度评定

曲率半径是球面光学元件中的重要参数之一,曲率半径的高精度测量已经成为光学元件使用与加工中的一个关键问题。提出了基于差动共焦法的曲率半径测量方法,研制了1套激光差动共焦曲率半径测量系统,并对2组曲率半径测量结果进行不确定度评定。结果表明,2组曲率半径的测量值均与标称值吻合,其相对误差为0.001 15%,两组测量数据的标准不确定度均优于3.211 1110-4 mm。     

Φ200mm口径长焦距球面干涉测试及装备

为实现对大尺寸光学材料及系统元件的高精度对准测试,设计了一种新型Φ200 mm口径长焦距准直干涉测试装置。该装置以球面标准镜作为参考镜,结合斐索型透射式干涉机制和长焦距准直测试原理对凹球面大曲率半径光学元件进行面形精度检测,最大测试口径为Φ226.67 mm,且球面标准镜和球面标准反射镜同轴共球心,大幅度减小了测试空腔距离。结果表明,该系统空腔测试精度PV值为0. 097λ@632. 8 nm,RMS值为0. 013λ@632. 8 nm,系统重复稳定性优于λ/500@632. 8 nm,可实现曲率半径为7 500～8 500 mm测试,且大曲率半径测试误差小于1/1 000。     

凹凸厚透镜曲率半径和折射率的测定

观察凹凸厚透镜的球面反射成像及折反折成像,利用这一实验现象结合物像公式测定凹凸厚透镜前后表面的曲率半径和折射率。该方法不仅可以修正薄透镜测量中忽略透镜厚度所产生的误差,而且可作为测量透镜焦距和曲率半径的设计性、研究性和创新性实验项目,有利于学生深刻理解共轴球面系统成像,掌握符号规则和几何光学的成像计算。     

φ100mm激光平面干涉仪

激光平面干涉仪是测定平面的平直度、局部误差及平行平面平行度的仪器。φ100mm激光平面干涉仪是国营长江光学仪器厂在长期实践中试制成功的,使用该仪器可以测量接近平面的非平面度和大曲率半径球面的曲率。     

高精度光学对准测量装置的设计

设计了一套光学对准测量装置,该装置主要由面阵CCD相机、光学镜头、图像处理模块、LED红光光源、球面反光镜组成。介绍了测量原理,测量目标采用等腰三角形排列,通过面阵CCD对目标所反射的图像进行采集,由图像处理模块对该图像进行实时处理,能够同时得到X、Y、Z以及旋转角度等四维坐标数据。推导了光斑图像坐标和被测平面距离等计算公式,并进行了对准精度分析。结果表明,该装置位置误差〈1mm,角度误差为0．24°,实现了高精度、自动、快速对准测量。     

大口径球面反射镜曲率半径的精确测量

介绍了大口径球面反射镜曲率半径的传统测量方法,提出了利用组合测杆结合激光干涉仪测量球面反射镜曲率半径的新方法。首先利用激光干涉仪检测球面反射镜的面型,调整干涉仪与被测镜的位置,使被测镜达到零条纹干涉状态,然后架设合理长度组合测杆,调整组合测杆靠近干涉仪端测量球头的位置,使之达到零条纹干涉状态,再使组合测杆另一端测头与镜面接触完成测量,通过计算分析即可得到被测球面镜的曲率半径。对该方法的基本测量原理进行了研究分析,并对口径为600 mm的望远镜球面主镜的曲率半径进行了多次测量,测得其曲率半径均值为2 836.774 mm,标准偏差为0.071 mm。最后对该方法的测量不确定度进行了分析,找出了影响测量精度的主要因素,合成标准不确定度为0.061 mm。     

大口径球面反射镜曲率半径的精确测量

介绍了大口径球面反射镜曲率半径的传统测量方法,提出了利用组合测杆结合激光干涉仪测量球面反射镜曲率半径的新方法。首先利用激光干涉仪检测球面反射镜的面型,调整干涉仪与被测镜的位置,使被测镜达到零条纹干涉状态,然后架设合理长度组合测杆,调整组合测杆靠近干涉仪端测量球头的位置,使之达到零条纹干涉状态,再使组合测杆另一端测头与镜面接触完成测量,通过计算分析即可得到被测球面镜的曲率半径。对该方法的基本测量原理进行了研究分析,并对口径为600 mm的望远镜球面主镜的曲率半径进行了多次测量,测得其曲率半径均值为2 836.774 mm,标准偏差为0.071 mm。最后对该方法的测量不确定度进行了分析,找出了影响测量精度的主要因素,合成标准不确定度为0.061 mm。     

一种测量球面透镜的系列化球径千分尺

提出了一种测量球面透镜的球径千分尺,按不同测量范围形成系列化规格,可手持操作类似于公知的千分尺,既可连续测量又能直读球面曲率半径,适用于生产加工中现场检测的实际需要。     

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.     

圆锥透镜对倾斜球面波光束的衍射模式

由于球面波入射圆锥透镜所产生的出射光束具有焦深长和中心光斑直径较小的特点,适合激光通信以及长距离测量.在实际使用中,入射球面波很可能与圆锥透镜的光轴发生倾斜.研究了圆锥透镜对倾斜球面波光束的衍射特性,通过基尔霍夫衍射理论以及稳相法分析,分析了其径向衍射光场分布形式,并用计算机进行了仿真.使用了半径为15 mm、底角为1°的圆锥透镜进行实验,并对仿真结果进行了验证.仿真和实验证明,减小入射球面波曲率半径、出射光束传输距离和入射光束倾斜角都可以减弱入射光束倾斜对衍射图的影响.     

Linear method for evaluation of radius of spherical surface from discrete set of data points

Our work deals with the problem of evaluation of the spherical surface parameters from the discrete set of measured data points. We propose a new linear method for determination of the center and the radius of curvature of the measured spherical surface. Such method can be used for evaluation of the measurements obtained from both contact and noncontact 3D coordinate measuring machines. We perform an analysis of the proposed sphere fitting method and we verify that the obtained results are comparable to results calculated using existing techniques. Finally, the proposed algorithm is implemented for evaluation of real measurements of spherical optical surfaces using the designed scanning chromatic confocal system.     

A Variation of Schwarzschild Telescope: Golden Section Solution with Two Concentric Spheres and Its Extension to Finite Distance Solutions

Imaging by two concentric spheres is studied by geometrical method. As the system is symmetric with respect to the common center of curvature, peripheral aberrations, namely coma, astigmatism, and distortion, do not appear. The imaging surface is a sphere that shares the center of curvature with two mirrors. As we solve the zero spherical aberration condition for imaging of an object at infinite distance, the golden section number appears as the ratio of the distance between two mirrors and the radius of the primary mirror. For imaging of an object at finite distance, we have to increase the radius of the second mirror. This system also has no peripheral aberrations. Making the object surface spherical, we can obtain a flat image surface. As the spherical aberration is zero in the original system, spherical aberration, coma, and astigmatism remain zero when the object surface is curved.     

Assessing the Exact Muffin-Tin Orbitals method for the Bain path of metals

Abstract

We scrutinise the muffin-tin approximation and the screening within the framework of the Exact Muffin-Tin Orbitals method in the case of cubic and tetragonal crystal symmetries. Systematic total energy calculations are carried out for the Bain path including the body-centred cubic and face-centred cubic structures for a set of simple and transition metals. The present converged results in terms of potential sphere radius (S) and hard sphere radius (b) are in good agreement with previous theoretical calculations. We demonstrate that for all structures considered here, potential sphere radii around and slightly larger than the average Wigner–Seitz radius (w) yield accurate total energy results whereas S values smaller than w give large errors. It is shown that for converged total energies hard spheres with radii b = 0.7–0.8w should be used for an efficient screening within real space clusters consisting typically of 70–90 lattice sites. The less efficient convergence of the total energy in the case of small hard spheres is ascribed to the delocalisation of the screened spherical waves, which leads to inaccurate interstitial overlap matrix. The above conclusions are not significantly affected by the volume of the system.     

Experimental investigation of the Casimir force beyond the proximity-force approximation

The analysis of all Casimir force experiments using a sphere-plate geometry requires the use of the proximity-force approximation (PFA) to relate the Casimir force between a sphere and a flat plate to the Casimir energy between two parallel plates. Because it has been difficult to assess the PFA's range of applicability theoretically, we have conducted an experimental search for corrections to the PFA by measuring the Casimir force and force gradient between a gold-coated plate and five gold-coated spheres with different radii using a microelectromechanical torsion oscillator. For separations z<300 nm, we find that the magnitude of the fractional deviation from the PFA in the force gradient measurement is, at the 95% confidence level, less than 0.4z/R, where R is the radius of the sphere.     

A new method for determining hydrodynamic effects on the collision of two spheres

A sphere falling in a fluid may collide with another sphere falling more slowly if, when the spheres are far apart vertically, the horizontal distance between their centers is less than or equal to a critical radius. Accurate prediction of aerosol particle coagulation requires a good understanding of this process. Previously reported optical techniques for measuring hydrodynamic effects on this phenomenon have inherent difficulties detecting grazing collisions and hence in determining the critical radius. In this work, a novel detection technique is demonstrated and it is shown that the critical radius may be determined from the sound generated by the collision of two spheres in a viscous liquid. The technique is shown to provide a more precise and decisive indication of when hard spheres collide.     

THz波段亚波长半导体球形阵列光学特性的数值模拟

利用T-matrix方法对太赫兹波段亚波长半导体球形阵列进行了数值模拟并在数值模拟结果的基础上讨论了其光学特性。在太赫兹波段可以通过掺杂等手段调节半导体的表面等离子体特性。以半导体InSb为例并采用Drude模型,对单个亚波长球及两个或多个亚波长球组成的阵列进行了数值模拟,主要以归一化消光截面为参数,讨论了不同阵元半径、不同球形单元间距、不同单元数目及入射波不同极化方向对阵列特性的影响。     

Three-dimensional coherent diffraction imaging of Mie-scattering spheres by laser single-orientation measurement

Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional(3D) structure can be determined by a single orientation diffraction measurement for a phase object of double-layer Mie-scattering silica spheres on a Si3N4 membrane. Coherent diffraction pattern at high numerical aperture was acquired with an optical laser, and the oversampled pattern was projected from a planar detector onto the Ewald sphere.The double-layered spheres are reconstructed from the spherical diffraction pattern and a 2D curvature-corrected pattern,which improve convergence speed and stability of reconstruction.