折/衍混合透视型头盔显示器光学系统设计

为满足头盔显示器(HMD)对大视场、高像质和彩色显示的要求,提出了改进型 HMD 光学系统。该系统以彩色 LCD 为图像源实现彩色显示;以折/衍混合单透镜代替双胶合,利用其负色散和波面任意整形特性消除系统色差及改善波前像差。图像源发出的光束在分束器附近成中间像,可增大系统视场;出瞳在中继光学组元中间成像,可减小系统口径,增大出瞳直径;球面耦合器将分束器反射过来的光束准直后投射到人眼,能消除人眼反复观察不同焦距的视频图像和外界图像所造成的疲劳。该系统垂轴色差小于 42μm,视场扩大为 40°(水平)×30°(垂直),分辨力接近人眼的最小分辨能力;口径小于 46mm,重量比现有 HMD 光学系统下降 47%。     

双目光学透视式头盔显示器的实验研究

采用分立元件研制双目光学透视式头盔显示器,对双目透视式头盔显示中的关键问题进行实验研究.用偏振分光棱镜作为组合镜,通过理论分析,发现图像源和外界环境的亮度随偏振片方位角呈余弦变化规律,并通过调整偏振片使头盔显示器的图像与外界环境达到最佳融合状态.调查研究了头盔显示器双目重叠范围的改变对视觉效果的影响,数据结果显示,双目重叠范围为单目视场的33～50%时效果最佳.最后根据视差原理编程制作立体图像对,分别显示于头盔显示器的左右眼,实现立体显示.     

眼镜式虚拟显示折射/衍射塑料光学系统设计

研究了塑料透镜在3D虚拟显示头盔光学系统中的应用,设计了适用于眼镜式虚拟微显示器的全塑料(聚甲基丙烯酸甲脂-PMMA)光学系统.引入反射镜来折叠光路以缩短系统长度,引入衍射面,利用其负色散性和波面任意整形特性来消除系统色差及改善波前像差.该系统重量仅为9.8 g.目视系统中需重点校正的像散和垂轴色差的最大值分别为0.31 mm和8.8μm,最大畸变<7%.系统最小角分辨力为0.8mrad,全视场为32..     

折叠式激光投影光刻物镜的设计研究

针对大面积、高产量和节约型印制电路板(PCB)生产使用的激光投影光刻机,利用ZEMAX工程光学设计软件,对其投影系统进行了模拟设计与优化,并对优化后的结果进行了分析.对于设计的激光投影系统,其特征尺寸分辨力达到了9μm,全视场波像差小于λ/4,畸变小于0.000007%,这些指标符合实际要求.     

超短焦全景鱼眼镜头的研究与设计

着重分析了超短焦鱼眼镜头焦距与分辨率的关系,表明了像面尺寸一定的前提下焦距越短,全景展开的环景边缘分辨率越高。基于以上理念,依据超短焦全景镜头设计思路,设计了一款焦距像高比≤0.35,水平视场角 =360°,垂直视场角 ≥180°的全景鱼眼镜头。设计结果表明：在空间频率为 200 lp/mm处的 MTF值大于 0.4,接近衍射极限;在垂直半视场角 45°～90°的环景边缘区域拥有大于 75%的像素空间,使得环景展开后仍然具有较高的分辨率,从而代替多台不同方位的高解摄像机,实现高清全景监控。     

图像尺寸测量中镜头畸变的影响及校正研究

图像尺寸测量是一种非接触式测量技术,系统中的光学镜头畸变严重影响测量的精度.提出利用图像识别技术和最小二乘法,拟合出标准线经成像系统所得到的畸变曲线函数,根据曲线上任一位置的曲率大小来表征镜头畸变率的大小.通过软件编程,直接得出被测镜头各空间区域的畸变率大小.利用测量结果对畸变图像进行校正,通过实验验证,图像尺寸测量的...     

粗测凤凰24mm F2.8定焦镜头

很早就听说凤凰光学公司生产了一款24mmF2.8广角镜头,但一直没有见到.去年10月份在当地凤凰公司购得这款镜头,该镜头焦距24mm F2.8,镜头号2000864,PK卡口,视场角83.4°,光学结构8片7组,最近拍摄距离0.3m,镜头直径φ63mm,长度65.5mm,重量294g.     

基于模糊神经网络的双目视觉系统的研究与准确度

在机器视觉系统中,由于深度信息的丢失,镜头的畸变等因素的影响,使得摄像机的模型是非线性的.在采用模糊神经网络对双目视觉系统标定时,以特征点投影到左右图像的坐标为4路输入,以网络的3路输出和该对应点在世界坐标系坐标的均方值为性能指标;根据梯度下降法来调整和最终获得一组稳定的隐含神经元与输出神经元之间的连接权值,以及高斯型隶属函数的参数(均值与标准差);这样可以用模糊神经网络的权值与隶属函数来代替双目视觉系统两个摄像机的投影矩阵,以描述三维空间特征点坐标与对应点在左右摄像机图像之间的关系,实现系统的标定.     

采用LD的光源步进条纹投影三维测量系统

在采用LED的光源步进法三维测量系统中,由于LED发散角大,在短距离内就达到较大的条纹投影面积,造成系统工作距离短.另外大功率LED发光面尺寸大导致条纹对比度低,投影高亮度、高对比度的条纹困难.为解决上述问题,提出在光源步进法投影装置中采用激光二极管(LD)作为光源,实现高亮度、高对比度相移条纹投影.采用该投影装置与双目摄像机设计了便携、高速的三维测量系统.首先利用改进的傅里叶变换轮廓术获取变形条纹相位及调制强度;接着利用激光散斑的随机性,在调制强度图中实现双目图像的粗匹配;然后在粗匹配的基础上进行条纹相位展开,利用相位实现精匹配;最后获得待测物体三维形貌.利用设计的系统进行了实验验证.系统的测量体积为360 mm×290 mm×100 mm,采集的三维数据最多为1280×1024点.实现了100 f/s的三维形貌测量速度,对平面的测量标准偏差为0.19 mm,对5个间隔距离为1.00 mm的平面进行了测量,测量距离的平均误差为0.05 mm.     

数字光刻缩微投影系统物镜的设计

针对高精度数字光刻的缩微光学投影系统,提出并设计了一种适用于0.7XGA型数字微反射镜(DMD)的6片式数字光刻缩微投影物镜。通过优化和拼接三片式物镜结构,得到数值孔径NA=0.1,放大倍率为-0.2558,分辨力达3.5μm,不受DMD栅格效应影响且达到衍射极限的缩微物镜。经过Zemax软件模拟得到其全视场光程差小于λ/5,145cycles/mm处的调制传递函数(MTF)大于0.58,充分说明该缩微物镜已经达到光刻物镜设计要求。利用Monte Carlo分析方法,模拟加工装配了100组镜头,设定空间频率为145cycles/mm时,90%的镜头FMTF>0.55,验证了加工装配实际可行。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.