改进的宽谱段车尔尼-特纳光谱成像系统设计

针对传统的车尔尼-特纳光谱仪像散较大的缺点,基于像差理论,提出了一种改进的车尔尼-特纳光谱成像系统.将平面光栅置于发散光中,利用平面光栅产生的像散来补偿物镜产生的像散.推导出了宽谱段像散同时校正条件,实现了宽谱段像散的同时校正.具体分析了像差校正的原理和方法,编制了初始结构快速计算程序.作为实例,设计了一个谱段为540～780 nm的宽谱段像散同时校正车尔尼-特纳光谱成像系统,利用光学设计软件ZEMAX-EE对该光谱成像系统进行了光线追迹和优化设计,并对设计结果进行了分析.结果表明,全视场调制传递函数在整个工作波段均达到0.52以上,实现了宽谱段像散的同时校正,并获得了良好的成像质量,满足了设计指标要求,结果也证实了所提出的改进方法是可行的.     

渐变焦眼镜片表面象散分布测量

描述了渐变焦眼镜片的非旋转轴对称非球面表面象散分布测呈，介绍了用泰曼一格林干涉仪和横向剪切干涉议的测量原理和方法，并将这两种仪器的测量结果进行了比较。     

The use of histograms for transmission electron microscopy: Defocus and astigmatism correction at high resolution

A real-time method for optimizing the defocus of a conventional transmission electron microscope in the phase contrast imaging mode has been investigated using image histogram data. This method can also be used to minimize the objective lens astigmatism. It will be shown both theoretically and empirically, using a digital television frame store, that a histogram will give the largest peak when an image has a broad and flat contrast transfer function. This method has distinct advantages of speed and minimal computational requirements over obtaining the power spectrum of an image.     

High resolution in-focus Lorentz electron microscopy

The Foucault in-focus method for viewing magnetic domains in a conventional electron microscope has been modified. The main feature of our modification is to introduce an aperture below the intermediate lens and to use it for stopping out one part of the split central spot instead of the objective aperture. This arrangement substantially reduces the axial astigmatism due to the objective aperture and makes it possible to reach the point resolution 5–6 nm in both light and dark domains. The image resolution is limited by the small image magnification achieved using the three-stage optical system of a Tesla BS 413 microscope.     

Accurate stigmating of a high voltage electron microscope

To reach the 0·2 nm point-to-point resolution possible with some high voltage electron microscopes, the astigmatism of the objective lens must be compensated to within 5 nm. Due to a number of factors the resolution of the image seen on the viewing screen of the high voltage microscope is, however, quite poor and does not permit compensation of such accuracy. We describe a technique for evaluating and correcting the astigmatism that starts from a recorded micrograph of a thin amorphous specimen. The astigmatism is determined from the optical diffraction pattern using a variation of the Thon method. This variation avoids any direct measurement of the radii of the contrast transfer zones, and is extremely rapid and convenient. Adjusting the stigmator coil currents, calibrated in terms of their stigmating power, for zero astigmatism completes the correction in less than 10 min after the recording of the micrograph.     

Astigmatic intensity equation for electron microscopy based phase retrieval

Phase retrieval, in principle, can be performed in a transmission electron microscope (TEM) using arbitrary aberrations of electron waves; provided that the aberrations are well-characterised and known. For example, the transport of intensity equation (TIE) can be used to infer the phase from a through-focus series of images. In this work an "astigmatic intensity equation" (AIE) is considered, which relates phase gradients to intensity variations caused by TEM objective lens focus and astigmatism variations. Within the paraxial approximation, it is shown that an exact solution of the AIE for the phase can be obtained using efficient Fourier transform methods. Experimental requirements for using the AIE are the measurement of a through-focus derivative and another intensity derivative, which is taken with respect to objective lens astigmatism variation. Two quasi-experimental investigations are conducted to test the validity of the solution.     

Measurement of twofold astigmatism of probe-forming lens using low-order zone-axis ronchigram

By using a low-order zone-axis ronchigram of a crystalline sample, a simple method for measuring twofold astigmatism of a probe-forming lens is proposed. This method allows precise measurement of the value of astigmatism from only one experimental ronchigram.     

插针式简易定中心法在红外物镜装配中的应用

为了使红外热像产品获得更好的物镜光学成像质量,对物镜玻璃进行定中心为一有效的控制方法。在红外物镜的装配和调校过程中,通过采用插针式简易定中心法,其光学成像质量明显提高。对应用此法装配的物镜进行调制传递函数测试,其结果接近理论水平。用经测试的物镜装成整机进行整体试验测试,全部满足光学设计要求。     

A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope

We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic‐scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light‐collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, a beam profile in the form of an error function can be obtained and by repeating this with the knife edge at different axial positions relative to the beam waist, the divergence and astigmatism of the postobjective laser beam can be obtained. The measured divergence can be used to quantify how much of the full numerical aperture of the lens is used in practice. We present data of the beam radius, beam divergence, ellipticity and astigmatism obtained with low (0.15, 0.7) and high (1.3) numerical aperture lenses and lasers commonly used in confocal and multiphoton laser scanning microscopy. Our knife‐edge method has several advantages over alternative knife‐edge methods used in microscopy including that the knife edge is easy to prepare, that the beam can be characterized also directly under a cover slip, as necessary to reduce spherical aberrations for objectives designed to be used with a cover slip, and it is suitable for use with commercial laser scanning microscopes where access to the laser beam can be limited.     

基于像散原理的并行共聚焦探测曲线灵敏度研究

为了高效、快速的实现微结构三维可视化,对基于像散原理并行共聚焦光学系统中探测曲线过零点灵敏度的影响因素进行了研究.从几何光学的角度,建立探测曲线过零点的灵敏度与柱面镜组参数之间的关系,然后利用Zemax对结论进行仿真,其结果提供了获得最佳柱面镜参数及其设计方法.同时,为了进一步提高探测曲线灵敏度,对已有的四象限法进行改...     

大时间热响应常数投影物镜超高精度温度控制

为满足高分辨率光刻机控制大时间热响应常数投影物镜温度时响应速度和超高精度的要求,设计了前馈—串级水冷投影物镜温控系统。该系统以物镜为主控对象、冷却循环水为副控对象。针对物镜的慢动态温度变化特征,采用模型预测控制作为外环主控制算法;针对冷却水远传回路的纯时滞特性,采用带Smith预估器的PID控制作为内环副控制算法;为解决光刻机在不同工况下激光光路对物镜温度的严重扰动,引入前馈补偿控制激光热扰动。最后,在不同控制结构和热干扰条件下,进行了模拟物镜温度控制实验。结果显示,物镜温度稳态误差曲线在±0.01 ℃内波动。实验证明该系统极大地提高了物镜的温度收敛速度,具有较强的抗干扰能力,能满足物镜的超高精度温度控制要求。     

柱面系统无畸变指纹采集仪的光学设计

针对以往无畸变指纹采集仪多采用棱镜补偿方案,系统存在棱镜的固有像散,光学系统难以补偿这种像差获得较高成像质量这一问题,提出了一种采用柱面系统结合双远心物镜校正投影畸变的新方案。该方案利用双柱面系统,在棱镜没有压缩图像的方向上压缩图像;利用双远心光路,消除物面和像面存在倾斜时的梯形畸变。采用该方案进行的计算机建模,经过合理调整优化函数,平衡各种像差,获得了比棱镜补偿校正畸变方案更高的成像质量。指纹采集仪得到了指纹采集方(物方)大部分视场的传递函数值在特征频率5 lp/mm(对应像方40 lp/mm)时＞0.377, 在特征频率10 lp/mm(对应像方80 lp/mm)时＞0.139的结果,大部分视场传递函数提高到棱镜补偿方案的1.6倍,同时各视场成像质量都比较均衡。     

An optical configuration for fastidious STEM detector calibration and the effect of the objective‐lens pre‐field

In the scanning transmission electron microscope, an accurate knowledge of detector collection angles is paramount in order to quantify signals on an absolute scale. Here we present an optical configuration designed for the accurate measurement of collection angles for both image‐detectors and energy‐loss spectrometers. By deflecting a parallel electron beam, carefully calibrated using a diffraction pattern from a known material, we can directly observe the projection‐distortion in the post‐specimen lenses of probe‐corrected instruments, the 3‐fold caustic when an image‐corrector is fitted, and any misalignment of imaging detectors or spectrometer apertures. We also discuss for the first time, the effect that higher‐order aberrations in the objective‐lens pre‐field has on such an angle‐based detector mapping procedure.     

非制冷红外物镜设计中最佳波段的选择

根据常用大气窗口和常见物体辐射峰值波长,计算出黑体在233~313K范围内的光谱辐射出射度,结合红外探测器的光谱响应曲线得到非制冷红外镜头的设计波长及其权重。将该方法应用于实际物镜设计,发现光学系统波长及权重符合探测器焦平面输出信号光谱响应特性。该方法对非制冷红外热像光学系统的设计具有实际意义。     

0.8×~8×新型连续变倍体视显微镜物镜的设计

介绍变倍范围0.8×～8×连续变倍体视显微镜物镜的光学变倍原理.通过计算得出前固定组、变倍组、补偿组和后固定组焦距分别为43.149mm、-26mm、-26mm和54.846mm,利用Zemax光学设计软件在数值孔径取0.15～0.2条件下各自进行优化得到初始结构参数.组合后进一步优化,数值孔径取0.1,得出最终结构参...     

菲涅耳透镜的通光分析及设计方法探讨

研究了菲涅耳透镜成像质量差的原因,提出一种改进的方法,即改善轴外点的成像质量以增大菲涅耳透镜的视场。分析了三种常用的设计菲涅耳透镜的方法,用光学设计软件Zem ax模拟设计结果,对三种设计方法进行比较。得出结论:像面为曲面时可校正场曲;基面和底面为曲面的菲涅耳透镜与平面型菲涅尔透镜相比彗差较小。     

高度局域线偏振时空光涡旋的生成方法

携带横向轨道角动量的时空光涡旋是一种新型光脉冲波包,受到越来越多的关注。本文报道一种经过高数值孔径透镜聚焦,在透镜焦平面上产生偏振态可控的线偏振时空光涡旋的方法。为克服聚焦透镜对入射时空涡旋产生的时空像散效应,需对入射时空波包作预劈裂处理。基于Richards Wolf矢量衍射公式仿真了不同偏振态下的高度局域时空涡旋的三维时空场分布,并对其强度和相位特性进行了分析。生成的水平偏振、垂直偏振以及45°偏振高度局域时空涡旋证明了本文所提方法的有效性。     

Measurement of lens aberrations by means of image displacements in beam-tilt series

Electron microscope image aberrations are determined by means of the beam tilt/image displacement method with respect to the precision required to obtain a resolution of 1 A. The method simultaneously yields all image aberrations to the fourth order and it is independent of the material used for the procedure. The experimental procedure using amorphous carbon is described and errors in measuring beam-tilt angles, magnifications and image displacements can be kept sufficiently small to achieve the required accuracy. The method is applied to determine aberration constants of a CM300 FEG/UT microscope with correction of the three-fold astigmatism. The coefficient of spherical aberration and the modulus of the three-fold astigmatism were measured to 0.60 (+/- 0.02) mm and 150 (+/- 50) nm, respectively. The beam tilt/image displacement procedure is also computer simulated using an amorphous model structure yielding the same values for the lens aberrations which are used for imaging. However, a coefficient of spherical aberration of 0.67 mm is obtained by applying the focus variation/diffractogram analysis on the same model.     

Optical microscopy with flexible axial capabilities using a vari‐focus liquid lens

The axial imaging range of optical microscopy is restricted by its fixed working plane and limited depth of field. In this paper, the axial capabilities of an off‐the‐shelf microscope is improved by inserting a liquid lens, which can be controlled by a driving electrical voltage, into the optical path of the microscope. First, the numerical formulas of the working distance and the magnification with the variation of the focus of the liquid lens are inferred using a ray tracing method and conclusion is obtained that the best position for inserting a liquid lens with consistent magnification is the aperture plane and the rear focal plane of the objective lens. Second, with the liquid lens embedded in the microscope, the numerical relationship between the magnification and the working distance of the proposed flexible‐axial‐capability microscope and the liquid lens driving voltage is calibrated and fitted using the inferred numerical formulas. Third, techniques including autofocus, extending depth of field and three‐dimensional imaging are researched and applied, improving the designed microscope to not only flexibly control its working distance, but also to extend the depth of field near the variable working plane. Experiments show that the presented flexible‐axial‐capability microscope has a long working distance range of 8 mm, and by calibrating the magnification curve within the working distance range, samples can be observed and measured precisely. The depth of field can be extended to 400 μm from the variable working plane and is 20 times that of the off‐the‐shelf microscope.     

10×连续变倍照摄像物镜的光学设计

连续变倍照摄像物镜在各种照相和摄像等领域有着广泛且必不可少的实际应用。通过大量反复研究与计算,在参考他人资料的基础上,设计出了可用于像方线视场16mm的照摄像机物镜,变焦范围为15~150mm连续变倍,物镜的像方F数为2.5,MTF曲线在50lp/mm时值均大于0.12,畸变在8%以内,是一成像质量满足实际要求的连续变倍物镜。