复合静电—磁浸没透镜的宽束曲轴聚焦性质及像差理论

研究了新型的复合静电－磁浸没透镜的曲光轴高斯电子光学性质及像差特性。应用宽束曲轴理论，导出了三维局部正交坐标系中的电子运动的中心轨迹方程和曲光轴的近轴轨迹方程；利用数学软件Mathematica推导出了复合静电－磁浸没透镜全部曲轴二级像差系数。作为实例，中针对轴上磁场和电场具有某种解析表达式的旋转对称的静电－磁浸没透镜系数，计算了它的曲轴高斯聚焦特性和二级像差，并给出了二级像差分布图形。     

无束腰的磁浸没透镜系统的理论研究和数值模拟

采用曲轴坐标系统 ,导出了磁浸没透镜的宽束曲光轴理论 ,研究了初始正则角动量矩不为零的无束腰磁透镜系统的电子光学性质 ;数值模拟出了能产生缩倍聚场分布的磁透镜结构 ,并计算了具有解析表达式的缩倍聚场的高斯成像性质 ,计算结果与传统的直接计算轨迹的方法一致     

无束腰的磁浸没透镜系统的理论研究和数值模拟

采用曲轴坐标系统，导出了磁浸没透镜的宽束曲光轴理论，研究了初始正则角动量矩不为零的无束腰磁透镜系统的电子光学性质；数值模拟出了能产生缩倍聚场分布的磁透镜结构，并计算了具有解析表达式的缩倍聚场的高斯成像性质，计算结果与传统的直接计算轨迹的方法一致。     

微分代数在高阶复合几何像差—色像差分析中的应用

微分代数是计算机数值计算领域中的一种强有力的新型数学方法,它为任意高阶微分的计算提供了一种可达到机器精度的极为简便的手段。本根据微分代数的基本原理,研究了它在高阶复合几何像差－色像差分析计算中的应用,得到了系统的任意阶传递性质的微分代数表达,并具体给出了一至三阶复合几何像差－色像差所对应的微分代数系数。中还以一个轴上电位分布具有解析表达式的静电电子透镜为例,计算了它的一至三阶复合几何像差－色像差系数,并给出了一阶色差分布图形。     

微分代在高阶复合几何像差-色像差分析中的应用

微分代数是计算机数值计算领域中的一种强有力的新型数学方法,它为任意高阶微分的计算提供了一种可达到机器精度的极为简便的手段.本文根据微分代数的基本原理,研究了它在高阶复合几何像差-色像差分析计算中的应用,得到了系统的任意阶传递性质的微分代数表示,并具体给出了一至三阶复合几何像差-色像差所对应的微分代数系数.文中还以一个轴上电位分布具有解析表达式的静电电子透镜为例,计算了它的一至三阶复合几何像差-色像差系数,并给出了一阶色差分布图形.     

真空科学与技术第22卷总目次

学术论文ＴａＮ/ＮｂＮ纳米多层膜的力学性能与耐磨性李戈扬　虞晓江　吴桢干等 (1)…………………………………………………复合静电 磁浸没透镜的宽束曲轴聚焦性质及像差理论程　敏　唐天同　姚振华　 (5 )……………………………………溶胶 凝胶法制备掺氟二氧化硅低介电常数薄膜陈　佾　沈　杰　徐　伟等 (10 )……………………………………………ＣｕＰｃ/ＺｎＳ多层复合薄膜的制备及光电性能的研究何智兵　张溪文　沈　鸽等 (15 )…………………………………………热处理对单壁碳纳米管场发射的影响张　浩　张兆祥　侯士敏等 (2 0 )……     

放映镜头的结构与使用注意事项

一、单片透镜的各种像差单片透镜存在许多缺点 ,它所成的像不能完全反映原物体的真实面貌。这种影像与原物体不一致的现象称为像差。透镜的像差可分为两种 ,由于透镜对各色光的折射率不同而引起的像差称色像差 ;由于透镜各部分对光的折射作用不同而引起的同一色光的像差 ,称单色像差。单色像差又分为球面像差、彗形像差、像散及像场弯曲和畸变等。1.球面像差(1)凸透镜的球面像差 :对凸透镜照射一束宽阔而与光轴平行的光线 ,经过透镜后不在光轴一点上汇集 ,这样一种被透镜折射后的光线焦点不一致的现象称为球面像差 ,如图 1所示。近轴光线在…     

环状光束通过球差透镜的聚焦特性

利用偏心高斯光束相干叠加的方法,建立了柱坐标系下环状光束的新模型.从广义衍射积分理论出发,经过大量数值计算分析,详细研究了环状光束通过球差透镜的聚焦特性,定量分析了环状光束的阶数L,M、偏心高斯光束的束腰宽度w0以及球差系数C4对聚焦光场实际焦点(轴上最大光强)位置以及轴上最大光强的影响.研究结果表明,本文提出的模型可统-描述基模高斯光束和环状光束.在透镜焦距和入射光束波长一定的情况下,环状光束通过球差透镜的聚焦特性不仅与透镜的球差系数C4有关,而且还与环状光束的阶数L,M以及偏心高斯光束的束腰宽度w0有关.     

二元平场透镜

讨论二元平场透镜的光学特性和象差。这种透镜不引入光焦度,当物体们我限远处孔径光阑与透镜重合时,不产生初级球差、彗差、轴用和轴外色差,但是它对场曲、畸变和轴上色差有贡献。给上用于校正双胶爱镜组的场曲的二元透镜实例。计算结果表明,二元透镜在平场光学系统中具有实用价值。     

高效率复合同轴全息透镜的研制

提出一种复合同轴全息透镜的设计制作方法。该设计方法采用两片离轴全息透镜复合,按使用情况在布喇格条件下进行消像差设计。制作的全息透镜具有衍射效率高和像差小的特点,适合任意给定再现波长的窄带光场合。实验研制了一个全息透镜,其再现衍射效率达到63% 。     

李代数在磁偏转系统三级像差计算中的应用

提出了电子光学偏转像差的李代数理论 ,将这种新型数学工具的应用领域从带电粒子束的聚焦传输系统推广到扫描偏转系统。推导出了磁偏转系统的高斯光学性质及全部三级正则像差 (包括在任意观察平面的正则位置像差和正则动量像差 ) ,所导出的结果与传统的逐次近似像差理论相同 ,为将李代数方法用于扫描探针系统的高阶像差的分析计算奠定了理论基础     

Hamiltonian magnetic optics

Starting from Hamilton's principle, the imaging properties of charged particle beams in arbitrary static magnetic fields are outlined. The magnetic scalar potential is expressed as a series of multipoles about an arbitrary space curve which need not necessarily coincide with a trajectory of the beam. Appropriate power series expansions are given for the components of the magnetic vector potential where the expansion coefficients are related to the complex curvature of the axis and the strengths of the multipole components of the magnetic scalar potential. The general laws which govern the propagation of the charged particles are discussed by means of Hamilton's characteristic functions. It is shown that the Poisson and the Lagrange brackets are equivalent representations of the symplectic condition. The Poincaré invariant is used for elucidating some characteristic imaging properties of magnetic fields.A perturbation eikonal is introduced which allows a systematic and simultaneous calculation of the geometrical and chromatic aberrations to any order. The method has the advantage that it reveals at the very beginning all interrelations between the aberration coefficients. The iteration procedure starts from the paraxial rays which are supposed to be known. The algorithm is especially suited for numerical calculation of the higher-order aberrations.     

Reduction of the effect of aberrations in a joint-transform correlator

We report the study of the influence of optical aberrations in a joint-transform correlator: The wave aberration of the optical system is computed from data obtained by ray tracing. Three situations are explored: We consider the aberration only in the first diffraction stage (generation of power spectrum), then only in the second (transformation of the power spectrum into correlation), and finally in both stages simultaneously. The results show that the quality of the correlation is determined mostly by the aberrations of the first diffraction stage and that we can optimize the setup by moving the cameras along the optical axis to a suitable position. The good agreement between the predicted data and the experimental results shows that the method explains well the behavior of optical diffraction systems when aberrations are taken into account.     

Control of spectral aberrations in a monochromator using a plane holographic chirped grating

A method aimed to minimize the impact of spectral aberrations in a monochromator is proposed in which the spectrum of the source of radiation under study is scanned by the rectilinear translation of a plane chirped grating. The chirped grating, which has a spatially variable groove spacing, is used to diffract and to spectrally focus the radiation. Imaging properties of the chirped grating were analyzed in order to develop the expression of the aberration coefficients of the system and the expression of the width of the instrument line shape due to aberrations. The optimal rectilinear trajectory required to operate the monochromator without significant spectral aberrations in measurements has been obtained numerically and tested in the laboratory. Experimental measurements of the emission spectrum of a seven-wavelength helium-neon laser are presented, as well as the sensitivity of the monochromator performance to different geometrical parameters.     

The design of a triplet with a shape-dependent third-order aberration optimization technique

Abstract

We have derived a series of shape-dependent third-order aberration equations involving lens thickness. These equations are used in a simple and direct method to correct real aberrations and to find the minimum aberration for triple design that has been proposed. These calculated third-order aberrations can exactly meet the target values for each stage by means of the damped least-squares method. The shape of the three elements permits the control of three third-order aberrations: spherical aberration, coma and astigmatism. The spherical aberration is targeted first. The minimal value of the real on-axis aberration is obtained. Similarly, the coma and astigmatism target values are adjusted so as to force the full field angle real off-axis aberrations down to a minimum. Finally, the manual adjustment of the lens thickness and air spacing is used to attain the minimum aberration at the 0.7 field angle. To verify the method, two triplet design examples are presented.     

Application of holographic diffractive doublets as collimators for highly elliptical light beams edge emitted from diode lasers

Two schemes for collimation of diode laser light beams with high cross-sectional ellipticity by means of a doublet of holographic diffractive elements are proposed and designed; one of the schemes is realized and tested. In both the schemes the first element of the doublet collimates the beam in the plane of the longer axis of the ellipse, and the second element collimates it in the perpendicular plane. Each element simulates a cylindrical lens. The set-up with the focal line of the cylindrical beam oriented perpendicular to the meridional plane is realized experimentally. The elements are holographic surface-relief gratings recorded in photoresist. For recording, only homocentric diverging beams are used, which minimizes potential aberrations and optical dirt. The parameters of the elements are computed using four equations, including one equation for compensation of the aberration of the lowest order. The doublet is proposed for the He—Ne red wavelength. A collimated He—Ne laser beam is employed for quality testing of collimation in a reverse way, with this beam impinging upon the second element. Characteristics of an outgoing beam from the first element of the doublet are recorded with a charge-coupled device camera. Calculated spot diagrams are compared with cylindrical focal lines captured separately from both the elements.     

Anterior corneal and internal contributions to peripheral aberrations of human eyes

Anterior corneal and internal component contributions to overall peripheral aberrations of five human eyes were determined, based on corneal topography and overall aberration measurements. Anterior corneal position and orientation (tilt) were referenced to the line of sight. Ray tracing was performed through the anterior cornea for 6-mm-diameter pupils at angles out to 40 degrees in both the temporal and the nasal visual fields. In general, both component and overall Zernike aberrations were greater for the nasal than for the temporal visual field. In general, the anterior corneal aberration components were considerably higher than the overall aberrations across the visual field and were balanced to a considerable degree by the internal ocular aberration components. The component and overall levels of Zernike third-order aberrations showed linear trends away from the fixation axis, and the component levels of Zernike fourth-order aberrations showed quadratic trends away from the fixation axis. The second-order, but not higher-order, aberration components were susceptible to the choice of image radius of curvature, while disregarding corneal position and orientation affected second- and higher-order aberration components.     

Improved solution for the cemented doublet

A method is described that permits the calculation of a cemented doublet with a given spherical aberration and coma at the edge of the lens. In particular the aberrations can be set to zero. Given one glass, the equations reported in this paper permit the determination of a second matching glass that minimizes the spherochromatism and coma of the lens. This result is obtained by the introduction, into the third-order thin-lens formulas, the third-order values of the aberration coefficients, as derived from the equation developed by Mossotti which yields zero finite aberrations for the same lens with added thickness. After a brief historical introduction, the third-order equations are developed and tables for the color-correcting glasses and SI and SII (the Seidel third-order coefficients) are given for objects at infinity and at a magnification of - 1, both for flint- and crown-leading cases. The paper closes with a table of corrected doublets.     

Third-order dispersion effects generated by non-ideal achromatic doublets on sub-20 femtosecond pulses

Gaussian temporal envelope pulses with initial durations of 10?fs, 15?fs and 20?fs and a carrier wavelength of 810?nm were analyzed at the paraxial focal plane of non-ideal achromatic doublet lenses for well-collimated incoming pulses parallel to the optical axis. The wave vector is expanded up to third order, to investigate the effect of third-order group velocity dispersion on the pulse and the results are compared to those obtained when the wave number is expanded up to second order. The propagation time difference and the primary spherical aberration were included in the calculations using the thin lens approximation theory. Results are presented for a homogenous illumination beam.     

Longitudinal chromatic aberration of an accelerating gap

An expression for the longitudinal chromatic aberration of an accelerating gap with an arbitrary distribution of the electrostatic field along the electron trajectory is presented, and a method is proposed for reducing it in time-transforming chronographs to values of order 10 fs. Pis’ma Zh. Tekh. Fiz. 25, 17–20 (April 26, 1999)