Multibeam laser writing of diffractive optical elements

A new version of the method of direct multibeam laser writing of diffractive optical elements (DOE) is proposed and investigated. A writing area in the form of an array of focused light spots is formed by splitting the writing laser beam into multiple beams by using a Dammann grating and focusing of these beams in the plane of a moving carrier with a photosensitive material. Adjustment of the radial pitch of writing and correction of the uniformity of the beam intensity is carried out by tilting the Dammann grating and displacing it in the dispersion direction. In writing DOEs, the radial pitch of discrete displacement of the writing area with respect to the plane of the DOE is set equal to or multiple of the average radial distance between the radial projections of the centers of the focused light spots. This version provides improved performance and accuracy due to high-quality paralleling of the writing beam and the averaging effect in superimposed writing.     

Ion beam etching of large aperture diffractive optical elements

总结了大尺寸衍射光学元件离子束刻蚀技术的研究进展.针对自行研制的KZ-400离子束刻蚀装置,提出了组合石墨束阑结构和多位置分步刻蚀策略来提高离子束刻蚀深度的均匀性,目前在450 mm尺寸内的刻蚀深度均匀性最高可达±1％.建立了针对多层介质膜光栅的衍射强度一维空间分布在线检测系统以及用于透射衍射光学元件离子束刻蚀深度的等厚干涉在线检测系统,实现了对大尺寸衍射光学元件离子束刻蚀终点的定量、科学控制,提高了元件离子束刻蚀工艺的成功率.利用上述技术,成功研制出一系列尺寸的多层介质膜光栅、光束采样光栅、色分离光栅以及同步辐射光栅等多种衍射光学元件.     

Dynamic correction of the laser beam coordinate in fabrication of large-sized diffractive elements for testing aspherical mirrors

This paper presents a method of improving the accuracy of a circular laser system in fabrication of large-diameter diffractive optical elements by means of a polar coordinate system and the results of their use. An algorithm for correcting positioning errors of a circular laser writing system developed at the Institute of Automation and Electrometry, SB RAS, is proposed and tested. Highprecision synthesized holograms fabricated by this method and the results of using these elements for testing the 6.5 m diameter aspheric mirror of the James Webb space telescope (JWST) are described..     

Collimation testing of laser beam with holographic optical elements

The shear elements in the shear interferometers of collimation test are commonly plane parallel plates or wedge plates of a small wedge angle. A new holographic shear element that acts as the wedge plate is proposed. The interferometer composed of holographic shear lenses has the advantages of high contrast fringes and adjustable shear amount. It posses the flexibility of altering the measurement sensitivity in a broad range, has more suitability and can meet different measuring requirements. Detailed analysis for the experimental configuration of this system is presented.     

坐标系变换在多件联动加工中的应用

通过设定局部坐标系和镜像坐标系等坐标系变换手段,调用子程序来实现工件多件联动加工,以提高生产率和减少、简化编程量。     

X射线干涉光刻光束线关键光学元件热-结构耦合分析

为了保证上海光源X射线干涉光刻光束线的稳定性,减小热变形对实验结果的影响,对X射线干涉光刻光束线的3个关键光学元件——偏转镜、聚焦镜和精密四刀狭缝进行热-结构耦合分析。首先,计算偏转镜、聚焦镜和精密四刀狭缝所承载的功率密度;然后,建立其有限元模型;最后,获得光学元件的温度场和热变形的结果。结果表明,偏转镜和聚焦镜采用间接水冷方式可有效抑制热变形,冷却后的最大面形误差分别为7.2μrad和9.2μrad。精密四刀狭缝未冷却时,刀片组件温度介于271.56~273.27℃,刀口热变形为0.19 mm,直线导轨热变形为0.08 mm;经过铜辫子冷却后,刀片组件温度降至22.24~23.94℃,刀口热变形降至0.2μm,直线导轨热变形降至0.1μm;采用影像法和接触探头法测试后,刀口直线度、平行度和重复精度均满足技术要求。偏转镜、聚焦镜和精密四刀狭缝的热变形通过间接水冷和铜辫子的冷却方式可以得到很大程度的抑制,进而保证光斑质量。     

基于坐标测量机的轴向立体视觉测量方法研究

为了解决双目立体视觉测量过程中图像匹配计算量大、算法复杂、误匹配率高的问题,提出了一种轴向立体视觉测量方法。该方法由单个摄像机沿坐标测量机轴向先后捕捉被测物表面,利用同轴摄像机外极线相互平行的特性进行同源相点的逐个匹配,并根据视差原理反求三维坐标。着重论述了该方法的原理、同源点匹配及具体实现过程,并通过实验进行了验证,测量了一个塑料盘的边缘并进行了重建。研究结果表明该方法能提高匹配效率,减小误匹配几率,实现快速高效的非接触式测量。     

坐标系旋转在加工圆锥面上孔系的应用

通过实例说明在数控加工中,通过工件坐标系旋转加工圆锥面上孔的方法。     

Laser technologies in micro-optics. Part 1. Fabrication of diffractive optical elements and photomasks with amplitude transmission

This paper is a review of studies carried out by the staff of the National Research University of Information Technologies, Mechanics and Optics (ITMO University, Saint-Petersburg) and the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences (IAE SB RAS, Novosibirsk) in the field of development of laser engineering processes for the formation of the structure of diffractive optical elements (DOEs) and photomasks with amplitude binary and grayscale transmission. This paper also describes the results of the study of laser thermochemical technology for fabricating chrome DOEs and technologies for the fabrication of grayscale DOEs and photomasks based on the use of amorphous silicon and LDW glass.     

Sensitivity of an optimized contour mask technique to errors in fabricating piecewise continuous relief diffractive optical elements

This paper considers the effect of errors in the technological process using an optimized contour mask technique for fabricating piecewise continuous relief diffractive optical elements on the reduction in the backward slopes of diffraction zones and the increase in the diffraction efficiency of the elements. The process parameter tolerances necessary for the implementation of the method are within the parameters of the standard microelectronic processes and equipment. The proposed method can be useful for laser writing systems and projection lithography that form the relief in a photoresist with a backward slope width exceeding 1 µm since it provides a significant improvement in the performance of the fabricated diffraction structures.     

开放式结构交流同步伺服电动机控制系统在单轴机器人、机械臂上的应用

分析了单轴机器人、机械臂控制系统的技术要求及系统工作流程,设计了系统的结构,并详细描述了系统的开放式架构与应用实现方案.     

Uncertainty analysis of a laser calibration system for evaluating the positioning accuracy of a numerically controlled axis of coordinate measuring machines and machine tools

This paper presents an uncertainty analysis of a Positional Error Calibrator based on a laser interferometer system. This laser calibration system is capable of evaluating the positioning accuracy of a numerically controlled axis of machine tools and coordinate measuring machines (CMM) under dynamic conditions. In order to assess the measurement uncertainty of this calibrator, an analysis of the uncertainty components that make up the uncertainty budget of this calibrator has been carried out. These uncertainty components can be classified into three categories as follows: (1) uncertainties intrinsic to the laser system; (2) uncertainties due to environmental effects; (3) measuring uncertainties due to the installation. The procedure for evaluating the uncertainty of this calibrator follows GUM (“Guide to the Expression of Uncertainty in Measurement”). This uncertainty analysis was carried out when this calibrator was used to assess the positional errors of the “X” axis of a moving bridge type CMM.     

3D manufacturing tolerancing with probing of a local work coordinate system

The safety and performance requirements for mechanisms are such that the necessary accuracy of part geometry is difficult to reach using classical manufacturing processes. This paper proposes a manufacturing tolerance stack-up method based on the analysis line method. This technique enables both the analysis and the synthesis of ISO manufacturing specifications through a new approach which relies on production specifications, adjustment specifications, and their analysis to stack up the 3D resultant. The originality of the method resides in the 3D calculation for location requirements, which takes into account angular effects and probing operations on numerical-control machine-tools in order to define a local work coordinate system (WCS). For achieving tolerance analysis, deviations are modeled using small-displacement torsor. This tolerance analysis method enables one to determine explicit three-dimensional linear relations between manufacturing tolerances and functional requirements. These relations can be used as constraints for tolerance optimization.     

Dynamic synthesis of a 2-degree-of-freedom function-generator with flexible elements

Kinematic synthesis of planar 2-degrees-of-freedom linkages with at least seven links hitherto reported in the literature is very difficult due to the highly nonlinear equations that result. Special techniques are needed to solve these nonlinear equations. Both the formulation and the solution are extremely tedious and time consuming. In what follows a linkage with a flexibly attached slider is proposed. The differential equation of motion of the slider mass and its solution lead to a much simpler displacement equation which can be used for the closed form synthesis of a function generator for two independent variables. The resulting equations are linear simultaneous, the solution of which is a routine matter. The dimensions obtained can be used as starting values for optimisation by least squares method etc. An example problem is solved to illustrate the application.     

Correction for non-perpendicularity of beam and tilt axis in tomographic reconstructions with the IMOD package

The surface characteristics of a large set of commercial lightweight coated paper grades are explored. The quantification of the 3D structure is revealed by atomic force microscopy, laser profilometry and X‐ray microtomography. This comprehensive study demonstrates the suitability of different and modern methods for assessing critical coating layer properties, thus identifying the right tools for specific structural analyses. Based on the assessment of the top and bottom surfaces of 25 commercial lightweight coated samples, three main conclusions can be drawn: (1) the facet orientation polar angle is a function of roughness, (2) skewness did not describe the surface details affecting the gloss of the commercial lightweight coated samples assessed in this study and (3) surface roughness at wavelengths below approximately 1.0 μm does not affect the paper gloss significantly. This is important knowledge for the understanding of lightweight coated paper surface structure and its properties.     

Assessment of movement distribution in the lumbar spine using the instantaneous axis of rotation

Journal of Mechanical Science and Technology - The position of the torso and the magnitude of exertion are thought to influence the distribution pattern of intervertebral movements within the...     

A new optical measurement system for determining the geometrical errors of rotary axis of a 5-axis miniaturized machine tool

Machine tools have greatly improved in recent decades. Among them, miniaturized machine tools (mMTs) that have advantages in terms of reduced energy consumption, space requirements, costs, and other resources are becoming more and more popular in the area of micro scale parts manufacturing. However it is exceedingly difficult to calibrate an mMT due to its small size. This paper proposes a novel method for identifying the geometrical errors of a rotary axis of miniaturized 5-axis machine tools using two position sensitive detectors (PSDs) and a laser diode. This work not only reduces the complication of the system structure and setup but also solves the problem of assembly. We propose a method to determine errors based on the geometrical position of PSDs, laser beam path, and its readout signals after each angle of rotation. The homogenous transformation approach is used to find the individual error components. A system sensitivity analysis is also presented in this paper.     

Dependence of the magnetic permeability on the polar coordinate in cylindrical specimens placed in an alternating homogeneous field

A solution of an electrodynamics problem regarding determination of the signal from a pickup coil with a cylindrical specimen having varying magnetic permeability that is placed into the coil is obtained as a function of the polar coordinate. The case of an alternating homogeneous field is considered. Computational models are suggested for studying the experimental dependences; these models allow one to make conclusions on the regularities of changes in the magnetic permeability in alternating fields. The appropriate plots are presented.Translated from Defektoskopiya, Vol. 40, No. 7, 2004, pp. 77–89.Original Russian Text Copyright © 2004 by Dyakin, Sandovskii, Dudarev.     

H型钢九辊矫直机的结构与液压系统分析

针对H型铜九辊矫直机的两种类型--九辊悬臂式变节距矫直机和九辊紧凑式双支撑矫直机,对其结构分别进行了介绍,并对这两种九辊矫直机液压系统中的压下调整和轴向调整液压系统进行了原理介绍和功能阐述.     

Development of dual-probe atomic force microscopy system using optical beam deflection sensors with obliquely incident laser beams

We developed a dual-probe (DP) atomic force microscopy (AFM) system that has two independently controlled probes. The deflection of each cantilever is measured by the optical beam deflection (OBD) method. In order to keep a large space over the two probes for an objective lens with a large numerical aperture, we employed the OBD sensors with obliquely incident laser beams. In this paper, we describe the details of our developed DP-AFM system, including analysis of the sensitivity of the OBD sensor for detection of the cantilever deflection. We also describe a method to eliminate the crosstalk caused by the vertical translation of the cantilever. In addition, we demonstrate simultaneous topographic imaging of a test sample by the two probes and surface potential measurement on an α-sexithiophene (α-6T) thin film by one probe while electrical charges were injected by the other probe.