用于瞬态三维测量的点衍射干涉系统

针对基于PZT移相的点衍射干涉三维测量系统中存在采样时间间隔过长和易受外界扰动影响等问题,提出了用于瞬态三维测量的点衍射干涉系统。通过对点衍射干涉三维测量系统光束偏振态调制并引入偏振相机,实现了三维空间坐标的瞬态移相干涉测量。针对偏振相机存在的视场误差及其对三维测量精度的影响,研究了基于相位插值的视场误差校正方法。为了验证系统方案的可行性,分别进行了数值仿真与三维在线测量比对实验。实验结果表明,利用本系统可实现亚微米量级的三维空间瞬态测量,且测量重复性小于5%。所提出的瞬态点衍射干涉系统具有对外界扰动不敏感、重复性测量精度高和快速测量等特点,为无导轨三维位移和尺寸等瞬态测量提供了一种可行的方法。     

用于在线检测的紧凑型瞬态干涉测量系统

针对不同口径光学元件加工阶段的在线测量需求,提出了用于在线检测的紧凑型瞬态干涉测量系统。系统引入偏振相机来实现波前瞬态移相干涉测量以降低外界扰动影响。同时结合基于位形优化算法的子孔径拼接技术,可降低对运动扫描平台精度要求,并实现大口径光学元件全口径检测。为验证所提出测量系统的可行性,分别对金刚石车削机床对中工具和大口径球面镜进行在线检测和子孔径拼接测量,结果表明,与ZYGO干涉仪检测结果相比,两者对应的均方根值偏差的绝对值分别为0.003与0.007μm。同时该系统具有布局结构紧凑和对外界环境扰动不敏感的特点,可很好地满足复杂环境在线安装检测应用要求,在金刚石车削机床对中工具的在线调整和不同口径光学元件在线检测中具有较广泛的应用。     

混频对全视场外差动态干涉仪测量精度的影响

全视场外差动态干涉仪在面形测量方面具有测量精度高、抗干扰能力强等优点,适合用于长焦距面形的动态干涉测量以及大口径光学元件的测量。但是干涉仪系统内部光学元件性能不理想以及元件装配存在误差等,会在干涉光路中引入频率混叠,影响干涉仪的测量精度。为了分析混频对全视场外差动态干涉仪测量精度的影响,从混频产生的原因出发,建立了由混频引入的测量误差的理论模型,分析了混频程度对测量精度的影响,分析结果表明,测量误差与混频程度呈非线性正相关,混频会造成测量面形结果上叠加一个和干涉条纹相同频率的周期性误差。搭建了全视场外差动态干涉测量实验系统,验证了不同混频程度对面形测量精度的影响,当混频程度为0.029时,面形测量误差为0.053λ;当混频程度为0.120时,面形测量误差为0.110λ,与仿真分析结果吻合。本文的研究对研制高精度全视场外差动态干涉仪具有实际意义。     

相位检测法定镜自适应校正技术

为保持傅里叶变换光谱仪在动镜运动和外界震动等恶劣条件下动镜和定镜间的准直性,采用了相位检测法检测准直性误差的定镜自适应校正技术。介绍了相位检测法的基本原理和实现自适应校正的途径以及自适应校正系统的基本结构。采用高速压电倾斜镜作为驱动补偿元件,分析了相位检测精度对校正精度的影响。实验结果表明,采用自适应校正后系统干涉效率明显提高。     

SPG-1型激光数字波面干涉仪干涉系统的设计、制造与装调

已经研制成功的SPG-1型激光数字波面干涉仪是激光技术、微机技术与干涉仪相结合而形成的一种新型光学面形的测试仪器。本文概述该仪器的设计指标及其依据,干涉系统的设计要求,设计结果,关键干涉元件的制造以及干涉系统的装调。仪器的最大口径为φ80mm,最高测量精度为λ/40,分辨率为λ/100,球面测量范围为500mm曲率半径以内.可以测量A级光学样板。干涉系统应有低的噪音、高的干涉条纹对比度及条纹亮度可调等要求。所采用的菲索型与泰曼型的干涉系统中,引入偏振元件而形成偏振干涉系统较好地满足了上述要求。仪器的自检误差优于0.04λ。为了使SPG-1型数字干涉仪及早产品化,提出了一个组合式的设计方案。     

全视场外差短相干形貌测量技术

针对工业检测中对微米量级测量精度、秒级测量时间的检测需求,提出了全视场外差短相干形貌测量方案。本方案采用短相干光源,实现大步长测量,节约扫描时间;采用全视场外差技术,实现干涉轮廓的快速反演,在抑制振动、直流噪声对测量精度影响的同时,提高数据反演的效率。搭建了实验验证系统,对测量时间和测量精度进行了实验验证,结果表明,系统的探测时长小于10 s,测量精度优于2μm。后续经进一步优化设计,探测时间可小于5 s,探测精度优于微米量级。该方案具有测量速度较快和测量精度较高等优势,在对效率要求较高的工业检测领域具有一定的应用前景。     

轴对称非球面绝对形状误差测量

正非球面光学元件表面形貌的干涉测量因须透过计算机全像片、零透镜等补偿元件提供与待测元件相匹配的理想非球面波前,故需严谨与复杂的程序进行测量系统即包含干涉仪内部光路系统对准误差、参考球面镜头与补偿元件等误差的校正。然而,测量结果亦包含镜片之夹持变形、承受重力的自重变形与测量环境的震动与气流扰动等信息,此类误差源对中大口径、测量光程长的光学元件的面形检测影响尤其大。近年,诸多文献探讨光学元件的绝对形状测量技术,透过多组态的测量架构     

一种便携式光学表面轮廓仪

研究了一种基于短相干光相移干涉法的便携式光学表面轮廓仪,分析了短相干光干涉显微镜相移干涉技术,实现了基于该项技术的光干涉显微系统。采用光路集成化的设计方法,实现了一体化轮廓仪光路集成,优化了机械三维调整测量台,实现了可用于大、小口径元件表面测量的正置、倒置两种测量模式。测试结果表明,仪器的粗糙度测量精度为0.1nm,重复性误差优于0.01nm,横向分辨率优于1μm。     

表面微观轮廓的高分辨率光学测量方法

较全面地介绍了用于表面微观轮廓测量的几种高分辨率甚至可达亚纳米的光学测量方法及其最新进展.文中重点描述了以扫描共焦显微检测法、离焦误差检测法为代表的光触针法,以TOPO轮廓仪、Nomarski显微镜、外差干涉轮廓仪、双焦干涉轮廓仪和同轴干涉轮廓仪为代表的干涉测量法和以扫描近场光学显微镜及光子扫描隧道显微镜为代表的近场光学法三种适用于表面微观轮廓测量的光学测量方法,分别介绍了其工作原理、特性、发展现状及存在问题,通过对这些方法的对比和总结,阐述了表面微观轮廓纳米级光学测量的发展趋势.     

数字化白光扫描干涉仪的研究

研究并设计实现了微形貌测量白光扫描干涉仪系统和光纤偏振耦合点监测白光扫描干涉仪系统.前者采用Mirau相移干涉形式,用压电陶瓷传感器PZT作移项器,主要用于微形貌测量,精度可达nm量级.后者采用光路补偿白光Michelson干涉形式,用格兰棱镜对偏振态进行调整控制,用移动参考臂来补偿由于耦合点所造成的光程差,光纤寄生偏振耦合测试仪的空间分辨率达到50mm,测量范围达到1km,探测灵敏度不小于-80dB(耦合模式与主模式的功率比).     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.