Electron extraction through an objective lens

The laws of electron motion in the field of a combined lens (composed of an electrostatic and magnetic lenses, as in a low-voltage scanning electron microscope) are considered. The character of the secondary- and backscattered-electron trajectories in the collimator field is analyzed taking into account the generalized electron momentum.     

Heating by absorption in the focus of an objective lens

We derive an integral solution for the local heating of a linearly absorbing, uniform medium exposed to strongly focused light. Numerical results for local heating under typical multiphoton microscopy and optical trapping conditions are presented for various aperture angles. In contrast with common Gaussian beam approximations, our model employs the focal-intensity distribution as described by the point spread function of the lens. In this way, the model also accounts for axial heat transportation, which results in a lower prediction for the temperature increase. For an aperture of 1.2 (water immersion), irradiation with 100 mW of 850-nm light for 1 s increases the local temperature of water by 0.2 K. Heating of water by linear absorption can be ruled out as a limiting factor in standard multiphoton-excitation microscopy.     

One-dimensional wavelength multiplexed microscope without objective lens

A new approach aimed to achieve microscopic imaging without objective lenses and based on wavelength multiplexing of the spatial object information is presented. The proposed method is used to develop, construct and experimentally validate a new type of optical microscope having no objective lens and no numerical reconstruction algorithms to allow imaging process. In order to extract the collected spatial information we use a spectrometer as part of our microscope system. Preliminary results are presented while considering two different types of one-dimensional (1-D) objects.     

透镜转像式军用瞄准镜物镜设计

为了满足瞄准镜体积小、重量轻的要求,需要物镜采用摄远型结构。分析了摄远型透镜转像式物镜的光学特性与像差特点,提出了摄远型镜组、正场镜和对称式转像镜组构成的结构型式。依据系统的成像特性,推导了光焦度分配和外形尺寸计算公式。采用光学设计软件Zemax设计了摄远型透镜转像式物镜,系统焦距为-100 mm,入瞳直径为25 mm,视场角为8,系统总长仅为99.92 mm。设计结果表明,采用该方法设计的瞄准镜物镜在40 lp/mm处各个视场的调制传递函数均在0.2以上,满足目视光学仪器的使用要求。     

Efficient cooling and trapping of strontium atoms

We report the capture of cold strontium atoms in a magneto-optical trap (MOT) at a rate of 4 x 10(10) atoms/s. The MOT is loaded from an atomic beam decelerated by a Zeeman slower operating with a focused laser beam. The 461-nm laser, used for both cooling and trapping, was generated by sum-frequency mixing in a KTP crystal with diode lasers at 813 nm and a Nd:YAG laser at 1064 nm. As much as 115 mW of blue light was obtained.     

Isotropic diffraction-limited focusing using a single objective lens

Focusing a light beam through a lens produces an anisotropic spot elongated along the optical axis, because the light comes from only one side of the focal point. Using the time-reversal concept, we show that isotropic focusing can be realized by placing a mirror after the focal point and shaping the incident beam. This idea is applied to confocal microscopy and brings about a dramatic improvement of the axial resolution.     

亚10 μm线宽的投影光刻物镜设计及其成像性能的实验测定

 采用Zemax软件设计出6镜片、数值孔径为0.06、2倍缩小、以405 nm半导体激光器为光源、分辨精度达5 μm、视场12 mm×12 mm 内波像差小于1/4波长、畸变小于0.005%的双远心投影光刻物镜的设计方法。将设计的物镜实物化,并对其光学传递函数(MTF)作精确的实验测定,利用所提出的MTF标准实验测量法,得到该投影物镜的成像性能达亚10 μm线宽。     

远焦型变焦距物镜的光组组合计算

介绍远焦型变焦距物镜的光学原理及光组组合计算方法，导出了高斯解计算公式。     

Single-element objective lens for soft x-ray differential interference contrast microscopy

High-resolution soft x-ray differential interference contrast (DIC) imaging was demonstrated through the use of a single-element objective, the XOR pattern, in a full-field soft x-ray microscope. DIC images of the magnetic domains in a 59 nm thick amorphous Gd25Fe75 layer were obtained and magnetic phase contributions were directly imaged. With its elemental, chemical, and magnetic specificity, compatibility with various sample environments, and ease of implementation, we expect this soft x-ray DIC technique to become one of the standard modes of operation for existing full-field soft x-ray microscopes.     

An electronic aperture for in-depth analysis of solids with an ion microprobe

An electronic aperture for in-depth concentration measurements with an ion microprobe is described. Measurements on polycrystalline metal samples were performed to test the ability of the instrument and its applicability in sputtering yield investigations. On an amorphous target the depth-resolution was found to be satisfactory but still amenable to improvement by a proper choice of primary ion energy and mass.     

聚焦透镜的像散对光阱力的影响

根据里查德-沃耳夫矢量积分公式,研究了径向偏振光通过具有像散的大数值孔径物镜后在焦点附近的光阱力。着重研究像散对轴向和横向光阱力的影响。研究结果表明,像散的存在导致了光阱力的势垒减弱,光阱中心的偏移,甚至是改变了有效捕捉区域,这将严重影响了光镊的轴向和横向对粒子的捕捉。通过对改变数值孔径的大小和孔径与光腰的比值,以及对不同大小的粒子捕捉效果的对比,可以改变像散对粒子捕捉影响的程度,从而改善像散对光阱力的影响,这对于光镊等精密仪器的操作是十分必要的。     

远焦小型线性变焦距物镜的设计原理

介绍远焦小型变焦距物镜的设计原理及方法。合理选取物镜的光学参数使变焦距物镜小型化 ;选取透镜的玻璃材料校正物镜的色差 ;采用适应法光学自动设计程序进行像差平衡 ,提高变焦距物镜的像质。所设计的变焦距物镜适用于多种医用内窥镜图像显示系统 ,其像质可与高分辨率的CCD图像传感器匹配。     

用于DVD光学头的刻环型双焦点物镜的设计

首先介绍了DVD读出系统对像差的要求 ,然后针对DVD光学头兼容CD盘片的要求介绍了刻环型双焦点物镜的基本结构和工作原理。详细介绍了适当的球面近轴参数的选取 ,包括使制造偏心灵敏度最小的物镜中心厚度的选取 ,物镜所需校正的像差种类以及如何选择优化变量等内容。最后给出了利用计算机设计的双焦点非球面物镜的设计结果 ,并讨论了刻环宽度选取的方法     

Electrodynamic trapping of spinless neutral atoms with an atom chip

Three-dimensional electrodynamic trapping of neutral atoms has been demonstrated. By applying time-varying inhomogeneous electric fields with micron-sized electrodes, nearly 10(2) strontium atoms in the 1S0 state have been trapped with a lifetime of 80 ms. In order to design the electrodes, we numerically analyzed the electric field and simulated atomic trajectories in the trap, which showed reasonable agreement with the experiment.     

TDX-200TEM物镜磁路缺陷对物镜性能影响研究

基于TDX-200透射电子显微镜(Transmission Electron Microscope,TEM),利用ANSYS软件仿真物镜磁路存在空隙、凹陷、凸起缺陷时物镜轴上的磁场分布,在此基础上利用MEBS软件仿真物镜激励、球差系数等性能参数,分析了各磁路缺陷对物镜分辨率的影响。结果表明,在相同加速电压下,相对于空隙缺陷、凸起缺陷对物镜分辨率的影响,凹陷缺陷对物镜分辨率的影响最大。在200k V加速电压下,当物镜存在直径为0.5mm的半圆形凹陷环缺陷时,实际分辨率相对于理想分辨率的变化量可达到9.68%。     

光刻投影物镜光学元件运动学支撑结构的设计与分析

为了实现曝光工作过程中深紫外投影光刻物镜的动态稳定性,设计了一种能够消除温度和应变影响的光学元件运动学支撑结构,研究了如何利用该支撑结构消除温度变化和外界应变对光学元件面形的影响。首先,计算单个支座的径向柔度,并与有限元分析结果进行比较。然后,分析在不同温度载荷和外界应变工况下光学元件上、下表面面形的变化,并与三点胶粘固定支撑方式下的结果进行了比较。计算结果表明：通过理论公式推导的支座径向柔度与仿真结果的误差绝对值小于2．2％;温度升高0．1℃时光学元件上下表面面形RMS值小于0．36nm;平面度公差5μm时面形RMS值小于0．05nm。与三点胶粘固定方式相比,运动学支撑方式能够有效消除温度变化和外界应变对光学元件表面面形的影响．     

A grazing-incidence dye laser with an intracavity lens

The performance of a nitrogen-laser-pumped dye laser, using a grating at grazing-incidence is greatly improved by inserting a lens between the dye cell and the grating. Long term operation of the laser with a 1.1 GHz linewidth is demonstrated.