高准确度光束偏转装置的设计与分析

基于矢量折射定理推导了光束经过正交双棱镜后的偏转表达式．给出了装置的主要设计参量；用数值模拟的方法分析了主要误差项，求出了总误差和实际准确度指标．结果表明，光束在水平张角及垂直张角500μrad内可实现准确度优于0．8μrad的偏转，偏离准确度主要受随机误差影响；反映到棱镜转角上的总误差为12．72arcsec，引起的光束偏离误差为0．365μrad。大于系统读数分辨率0．0387μrad，且小于光束偏离准确度指标0．8μrad．

Electromagnetic decay of the 1.7- and 2.43-MeV levels in ^9Be

The 1.7- and 2.43-MeV levels in ⁹Be were populated with the reaction ¹¹B(d, α)⁹Be* by bombarding thin boron on carbon foils with 1.7-MeV deuterons. The alpha particles were analyzed in energy with a surface-barrier counter set at the unique kinematically determined angle and the recoiling ⁹Be nuclei at 90^o were analyzed in rigidity with a magnetic spectrometer, in energy by a surface-barrier counter at the spectrometer focus, and in velocity by the time delay between an alpha and a ⁹Be count. When a pulse from the spectrometer counter was in the appropriate delayed coincidence with a pulse from the alpha counter, the two pulses were recorded in a two-dimensional pulse height analyzer. Most of the ⁹Be* decay by particle breakup. Only those that gamma decay are detected by the spectrometer counter. Thus the experiment provides a direct measurement of Γ_rad/Γ. Analysis of 384 observed events gives Γ_rad/Γ = (1.16 ± 0.14) X 10^-4 for the 2.43-MeV level. Combining this ratio with the value of Γ_rad = 0.122 ± 0.015 eV found from inelastic electron scattering gives Γ = (1.05 ± 0.18) keV. For the 1.7-MeV level, an upper limit, Γ_rad/Γ ≤ 2.4 = 10^-5, was determined.

Energy loss of light ions channeling in silicon

Experimental measurements of rate of energy loss were made for protons of energy .5 to 1.6 MeV channeling through 1 μm thick silicon targets along the <110>, <111>, and <211> axial directions, and the {100}, {110}, {111}, and {211} planar directions. A .05% resolution automatically controlled magnetic spectrometer was used. The data are presented graphically along with an extensive summary of data in the literature. The data taken cover a wider range of channels than has previously been examined, and are in agreement with the data of F. Eisen, et al., Radd. Eff. 13, 93 (1972).

The theory in the literature for channeling energy loss due to interaction with local electrons, core electrons, and distant valence electrons of the crystal atoms is summarized. Straggling is analyzed, and a computer program which calculates energy loss and straggling using this theory and the Moliere approximation to the Thomas Fermi potential, V_TF, and the detailed silicon crystal structure is described. Values for the local electron density Z_loc in each of the channels listed above are extracted from the data by graphical matching of the experimental and computer results.

Zeroth and second order contributions to Z_loc as a function of distance from the center of the channel were computed from ∇²V_TF = 4πρ for various channels in silicon. For data taken in this work and data of F. Eisen, et al., Rad. Eff. 13, 93 (1972), the calculated zeroth order contribution to Z_loc lies between the experimentally extracted Z_loc values obtained by using the peak and the leading edge of the transmission spectra, suggesting that the observed straggling is due both to statistical fluctuations and to path variation.

Measurement of the wavefront of a laser diode system for intersatellite communication by a Jamin double-shearing interferometer

The frame of a laser diode transmitter for intersatellite communication is concisely introduced. A simple, novel and visual method for measuring the diffraction-limited wavefront of the transmitter by a Jamin double-shearing interferometer is proposed. To verify the validity of the measurement, the far-field divergence of beam is additionally rigorously analysed in terms of the Fraunhofer diffraction. The measurement, the necessary analyses and discussion are given in detail. By directly measuring the fringe widths and quantitatively interpreting the interference fringes, the minimum detectable wavefront height (DWH) of the wavefront is only 0.2 gimel (the distance between the perfect plane wavefront and the actual wavefront at the transmitting aperture) and the corresponding divergence is only 65.84 mu rad. This indicates that the wavefront approaches the diffraction-limited condition. The results show that this interferometer is a powerful tool for testing the semiconductor laser beam's wavefront, especially the diffraction-limited wavefront.

一种基于PSD器件的改进型角度测量方法

提出一种基于平行平板干涉仪的改进型角度测量方法。为了实现较大的偏转角度测量，该平行平板干涉仪引入了一位置探测系统。平面反射镜的引入提高了角度测量的分辨率。实验验证了可在近3度的范围内实现被测偏转角度的高精度测量。并且作为一位相调制型干涉仪，其小角位移测量实验的重复精度可达5.5×10^(-8)rad。

Parallel plate interferometer with a reflecting mirror for measuring angular displacement

A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference (OPD) in the plane-parallel plate, which provides high sensitivity of the phase measurement. Detection of light transmitted through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer achieves a measurement repeatability of 10(-8) rad. (C) 2007 The Optical Society of Japan.

平行平板角位移干涉测量仪的优化设计

提出一种可提高平行平板角位移干涉测量仪测量精度的优化设计方法。对角位移干涉测量系统进行了误差分析，讨论了影响角位移测量精度的主要因素。分析了在干涉仪光路中入射到平行平板上的初始入射角度、平行平板的折射率以及厚度等参数的选取对角位移测量精度的影响。结果表明，优化选取最佳的初始入射角度以及元件参数，并在干涉光路中附加引入一平面反射镜形成光程差放大系统，可实现的角位移测量精度达10-8 rad数量级。

一种测量光刻机工件台方镜不平度的新方法

提出一种新的步进扫描投影光刻机工件台方镜不平度测量方法。以方镜平移补偿量与旋转补偿量为测量目标,使用两个双频激光干涉仪分别测量工件台在x和y方向的位置和旋转量；将方镜不平度的测量按照一定的偏移量分成若干个序列,每一个序列包括对方镜有效区域的若干次往返测量；根据所有序列的测量结果计算出方镜的旋转补偿量；为每一个序列建立临时边界条件,并据此计算出每一序列所测得的方镜粗略平移补偿量；采用三次样条插值与最小二乘法建立每一个序列间的关系,以平滑连接所有测量序列得到精确的方镜平移补偿量。结果表明,该方法用于测量方镜平

I. Anisotropy and crystal structure of ferromagnetic thin films. II. Investigations into magnetic microstructure by Lorentz microscopy

The induced magnetic uniaxial anisotropy of Ni-Fe alloy films has been shown to be related to the crystal structure of the film. By use of electron diffraction, the crystal structure or vacuum-deposited films was determined over the composition range 5% to 85% Ni, with substrate temperature during deposition at various temperatures in the range 25° to 500° C. The phase diagram determined in this way has boundaries which are in fair agreement with the equilibrium boundaries for bulk material above 400°C. The (α+ ɤ) mixture phase disappears below 100°C.

The measurement of uniaxial anisotropy field for 25% Ni-Fe alloy films deposited at temperatures in the range -80°C to 375°C has been carried out. Comparison of the crystal structure phase diagram with the present data and those published by Wilts indicates that the anisotropy is strongly sensitive to crystal structure. Others have proposed pair ordering as an important source of anisotropy because of an apparent peak in the anisotropy energy at about 50% Ni composition. The present work shows no such peak, and leads to the conclusion that pair ordering cannot be a dominant contributor.

Width of the 180° domain wall in 76% Ni-Fe alloy films as a function of film thickness up to 1800 Å was measured using the defocused mode of Lorentz microscopy. For the thinner films, the measured wall widths are in good agreement with earlier data obtained by Fuchs. For films thicker than 800 Å, the wall width increases with film thickness to about 9000 Å at 1800 Å film thickness. Similar measurements for polycrystalline Co films with thickness from 200 to 1500 Å have been made. The wall width increases from 3000 Å at 400 Å film thickness to about 6000 Å at 1500 Å film thickness. The wall widths for Ni-Fe and Co films are much greater than predicted by present theories. The validity of the classical determination of wall width is discussed, and the comparison of the present data with theoretical results is given.

Finally, an experimental study of ripple by Lorentz microscopy in Ni-Fe alloy films has been carried out. The following should be noted: (1) the only practical way to determine experimentally a meaningful wavelength is to find a well-defined ripple periodicity by visual inspection of a photomicrograph. (2) The average wavelength is of the order of 1µ. This value is in reasonable agreement with the main wavelength predicted by the theories developed by others. The dependence of wavelength on substrate deposition temperature, alloy composition and the external magnetic field has been also studied and the results are compared with theoretical predictions. (3) The experimental fact that the ripple structure could not be observed in completely epitaxial films gives confirmation that the ripple results from the randomness of crystallite orientation. Furthermore, the experimental observation that the ripple disappeared in the range 71 and 75% Ni supports the theory that the ripple amplitude is directly dependent on the crystalline anisotropy. An attempt to experimentally determine the order of magnitude of the ripple angle was carried out. The measured angle was about 0.02 rad. The discrepancy between the experimental data and the theoretical prediction is serious. The accurate experimental determination of ripple angle is an unsolved problem.

一种基于平板横向剪切干涉的角位移测量方法

在一种已有的角位移干涉测量技术的基础上,提出一种改进的角位移测量方法。通过选择合适的初始入射角,使从平板前后表面反射的两光束实现剪切干涉。采用一维位置探测器测量光束经透镜会聚后在探测器光敏面上的光点偏移量。根据干涉信号的相位和光点偏移量可以计算出被测物体的角位移。在该测量方案中,引入的一平面反射镜与被测物体的反射面形成光程差放大系统,提高了角位移测量灵敏度。分析了初始入射角对剪切比的影响,并讨论了基于该方案的角位移测量精度。实验结果表明,基于该技术的角位移重复测量精度达到10-8 rad数量级。

一种检测光刻机激光干涉仪测量系统非正交性的新方法

提出一种精确检测光刻机激光干涉仪测量系统非正交性的新方法。将对准标记曝光到硅片表面并进行显影;利用光学对准系统测量曝光到硅片上的对准标记理论曝光位置与实际读取位置的偏差;由推导的位置偏差与非正交因子、坐标轴尺度比例、过程引入误差的线性模型,根据最小二乘原理计算出干涉仪测量系统的非正交性。实验结果表明,利用该方法使用同一硅片在不同旋转角下进行测量,干涉仪测量系统非正交因子的测量重复精度优于0.01 μrad,坐标轴尺度比例的测量重复精度优于0.7×10-6。使用不同的硅片进行测量,非正交因子的测量再现性优于

一种使用双棱镜的动态小角度测量方法

提出一种基于正切关系和相位调制技术的动态小角度测量方法。使用双棱镜组成干涉测量臂引导两束平行光至分束棱镜处干涉,通过提取携带被测信息的干涉信号的相位实现动态的小角度测量。由于采用位置探测器(PSD)对测量臂中两平行光束的间距进行测量,简化了测量方程,消除了装置中双棱镜必须对称放置的要求。通过正弦地改变半导体激光器的注入电流在时域内实现对干涉信号的相位调制,形成准外差干涉测量模式,提高了光程差的测量精度。实验验证了该方法的可行性,并讨论了影响小角度测量精度的误差因素。研究结果表明,基于该方法的动态小角度的重

Accuracy analysis of parallel plate interferometer for angular displacement measurement

The measurement accuracy of a parallel-plate interferometer for angular displacement measurement is analyzed. The measurement accuracy of angular displacement is not only related to the accuracy of phase extraction, but also related to initial incident angle, refraction index and thickness of plane-parallel plate as well as wavelength's stability of laser diode, etc. Theoretical analysis and computer simulation show that the measurement error of the angular displacement bears a minimum value when choosing an optimal initial incident angle in a large range. These analytical results serve as a guide in practical measurement. In this interferometer, reducing the refraction index or increasing the thickness of the parallel plate can improve the measurement accuracy; and the relative error of the phase measurement is 3.0 x 10(-4) corresponding to 1 degrees C temperature variation. Based on these theoretical and experimental results, the measurement accuracy of the parallel-plate interferometer is up to an order of 10(-8) rad. (c) 2007 Elsevier Ltd. All rights reserved.

拼接光栅压缩器的时域特性

在拼接光栅和拼接光栅压缩器的设计中,子光栅调节偏差不可避免,各维偏差与拼接光栅的时间特性之间的关系很关键。通过脉冲压缩理论分析得到各维偏差和聚焦脉冲时间宽度展宽之间的解析关系,从数值计算结果分析,面平行左右偏差对脉冲的时间宽度影响较大,必须控制在21.08 μrad内；条纹密度差异对脉冲宽度的影响很显著,相对条纹密度的比值应控制在10-5以内；从消除角色散的角度分析,面平行俯仰偏差和条纹平行度偏差可以相互补偿,条纹密度差异和面平行左右偏差也可以相互补偿。

阵列光栅压缩器的空域特性

引入角度偏差、位移偏差作为拼接光栅系统的物理参数，定义了拼接光栅的孔径函数，利用傅里叶角谱理论研究了高斯脉冲入射拼接光栅压缩器后的远场分布特性。研究表明；出射脉冲仍然是高斯型脉冲，但包络中心发生偏移，偏移量由角度偏差量和光束口径决定；位移偏差引入的相位随着拼接光栅压缩器传递，其对远场焦斑的影响，取决于每片子光栅的非整数倍光栅常数的横向位移偏差和纵向位移偏差的综合作用。通过数值计算得到了各维偏差对阵列光栅压缩器空域特性的影响，计算表明：光栅面外角度偏差（俯仰左右）和条纹平行度偏差都必须控制在1μrad以内，