Folding mirror schlieren diffraction interferometer

We demonstrate the use of a mirror as a viewing diaphragm to generate a built-in diffracted reference beam in schlieren diffraction interferometry (SDI). The use of a mirror edge as a diffracting element instead of a conventional knife edge considerably enhances the contrast of the schlieren pattern, and it is shown to be equal to that of a phase knife edge. This increase in contrast is due to the fact that the otherwise unutilized diffracted beam in SDI is recombined in the described folding mirror geometry.     

A simple method for studying surface films on solids using transmission electron microscopy

A simple and rapid method for extracting and identifying a small amount of a foreign substance on the surface of a solid using a transmission electron microscope is developed. In this method surface species, such as contaminants, oxides or segregated surface films, are obtained by scraping a solid surface with a small piece of knife edge. The knife edge on which surface films adhere is then directly mounted on a microscope specimen holder for transmission electron microscopy observation. Pieces of surface films accumulated on the knife edge are found to be sufficient in quantity for phase identification using an electron diffraction method. Examples of this simple technique are taken from our recent structural study of gold electrodeposits.     

Calibration standard for laser beam profilers: method for absolute accuracy measurement with a Fresnel diffraction test pattern

The absolute accuracy of a clip-level laser beam profiler is measured to the 0.3% level, by comparison of the profiler's reading to the known width of a Fresnel diffraction test pattern. A pair of opposed knife edges, illuminated by a quasi-uniform and quasi-plane wave, generates the pattern whose width is determined by the 50% cut points in translating the edge pair across a tightly focused beam. The convolution of the scanning aperture with the diffraction fringe pattern is modeled to remove the effect of the aperture size from the accuracy test and to give a means of measuring the aperture width. Discussions of the experimental aspects of this test method show it to be an acceptable calibration standard for optical profilers, of use to those working on the International Standards Organization draft standard for laser beam parameter measurements.     

Conversion of evanescent waves into propagating waves by vibrating knife edge

Using plane wave spectrum methods, we analyze the propagation and mutual conversion of plane and evanescent waves generated by a one-dimensional object partially obscured by a vibrating knife edge. We show that subwavelength details of the object may be detected in each part of the transmitted plane wave spectrum, upon scanning the knife edge across the object. We discuss the implications for near-field scanning optical microscopy (NSOM) and compare some aspects of conventional NSOM (physical aperture), and vibrating knife edge (electronic aperture) approaches to the sampling of optical fields. © 1996 John Wiley & Sons, Inc.     

Micro-electro-mechanical system-based digitally controlled optical beam profiler

An optical beam profiler is introduced that uses a two-dimensional (2-D) small-tilt micromirror device. Its key features include fast speed, digital control, low polarization sensitivity, and wavelength independence. The use of this 2-D multipixel device opens up the important possibility of realizing several beam profile measurement concepts, such as a moving knife edge, a scanning slit, a moving pinhole, a variable aperture, and a 2-D photodiode array. The experimental proof of the optical beam profiler concept using a 2-D digital micromirror device to simulate the 2-D moving knife edge indicates a small measurement error of 0.19% compared with the expected number based on a Gaussian beam-propagation analysis. Other 2-D pixel arrays such as a liquid-crystal-based 90 degrees polarization rotator sandwiched between crossed polarizers can also be exploited for the optical beam whose polarization direction is known.     

弹性模量在用柔度法测量疲劳裂纹长度中的影响

用不同整体刀口设计的三点弯曲SE(B)试样做了两组疲劳裂纹扩展速率 (FCGR)试验 ,分析了弹性模量在柔度法测量疲劳裂纹长度中的影响。结果表明 ,用柔度法测量的弹性模量值偏大或偏小 ,都将影响到lg(da dN) lgΔK曲线的准确性 ,为在FCGR试验中采用SE(B)试样时整体刀口设计类型的选择提供了试验依据。     

连续热镀锌过程带钢边部气流特性的研究

为探究连续热镀锌气刀射流拭锌过程中发生的带钢边部压力衰减问题,设计了气流冲击平板实验,对带钢表面气流流向及压力进行测定.基于测量的参数,对该气刀射流喷吹过程进行数值模拟,并结合所推导的镀层厚度计算模型,对为减少带钢边部压力衰减所增设的边部挡板进行了厚度优化.研究结果表明:气刀喷吹时带钢边部气流发生横向偏转,使得带钢边部压力较中心处低,气压衰减率随气刀与带钢的间隔距离增加而增加,增设边部挡板能有效阻碍带钢边部压力衰减和降低边部过镀锌缺陷发生,且挡板厚度为2 mm时的作用效果最佳.     

Avoiding knife-edge countersinks in GLARE through dimpling

Traditional machine countersinking practices create a knife‐edge condition in one or more of the outer aluminium layers in riveted GLARE joints. Press countersinking (dimpling) provides an alternative method of countersinking that prevents the formation of a knife‐edge; however, its application and potential benefits to fatigue performance in GLARE are not known. This paper investigates the dimple‐forming process and its application to GLARE, and the resulting benefits in fatigue crack‐initiation life in unfilled rivet holes. Initial results showed that the limited formability of GLARE complicates the dimpling process, but that dimpling shows promise as a method for increasing the crack‐initiation life of riveted GLARE joints.     

Vakuumkomponenten für UHV und XHV aus Aluminium

Vacuum components of aluminum for UHV and XHV — mechanical strength The mechanical strength of 6000 series Al alloys is sufficient to generate stable CF knife edges. In order to preserve the mechanical strength it is vitally important that the maximum temperature of the material is not exceeded both during the production process and in the application. The suitability of these Al alloys in UHV and XHV applications is verified by measurements of the knife edge geometry.     

单模光纤模场直径（MFD）双刀口法快速测量系统的研究

本文依据标准的单模光纤模场直径（ＭＦＤ）刀口测量方法，提出了一种新颖独特的双刀口法测量方案并在实验室实现．此方法最突出的优点是：测量操作方便，简洁，可以实现全自动，测量精度相当高．     

B180H1天窗顶盖修边碎屑的解决措施

目的 采用五工序成形工艺生产天窗顶盖,中间及尾部R角和曲线造型修边工艺设计在OP20和OP40工序,研究此两序下天窗顶盖的修边刃口,改善零件的切边碎屑.方法 利用B180H1材质设计一种天窗冲压修边工艺及模具,建立天窗顶盖成形工艺,在生产过程中,通过调整刃口间隙、垂直度、符型、刃入量等改善修边碎屑.结果 在设计的OP20和OP40工序工艺中,修边刃口符型,两侧激光焊直边采用镶块而非整体结构,刃入量和刃口间隙分别为6 mm和0.035 mm,采用二级废料刀结构有效改善了修边碎屑.结论 天窗顶盖修边工艺排布在OP20和OP40工艺合理,修边碎屑和上下模修边刃口间隙、刃入量、废料刀相关,研配模具可以有效改善碎屑压伤,提升产品质量和实际生产效率.     

Beam blocking method for optical characterization of surfaces

A new method for measuring local topography of optical surfaces gives excellent lateral resolution. To obtain one‐dimensional image information, the surface is mechanically scanned at a slow rate and vibrated sinusoidally in the direction of the scan. The motion lies in a plane perpendicular to an incident, focused, probing laser beam. The reflected laser beam, angularly modulated by the moving variations in the vibrating surface, is gathered by a lens and directed toward a knife‐edge and photodiode combination. One half of the beam is blocked by the knife‐edge, the orientation of which is at a right angle with respect to the angular motion of the beam. The detected signal from the photodiode is proportional to the derivative of the local slope convolved with a spread function stemming from the surface vibration and the beam profile. The operational characteristics of the proposed method are superior compared with available methods. © 2001 John Wiley & Sons, Inc. Int J Imaging Syst Technol 11, 164–169, 2000     

Partially coherent image formation with x-ray microscopes

Image formation with partially coherent radiation is evaluated with the Hopkins formula and then applied to x-ray microscopy. Image characteristics expected from instruments with circular and annular pupils in partially coherent conditions are considered for two-point objects and a knife-edge object. The theoretically expected values for image characteristics that are easy accessible by an experiment, such as the width of a knife edge, are given for various x-ray microscopes.     

差动光栅在精密测试中的应用

提出差动光栅概念,举例说明差动光栅在光纤面板刀口响应测试和材料形变自动监测系统等精密测试中的应用。     

Decreasing the total divergence of polycapillary X-ray microbeams

The divergence characteristics of intense quasi-parallel X-ray microbeams have been studied at the output of the “microfocus X-ray generator-cylindrical polycapillary structure” system by scanning the beam with a knife edge. It us established that the total microbeam divergence decreases in the region near the output edge of the polycapillary structure (divergence quasi-decrease effect).     

Controlled nanocutting of graphene

Rapid progress in graphene-based applications is calling for new processing techniques for creating graphene components with different shapes, sizes, and edge structures. Here we report a controlled cutting process for graphene sheets, using nickel nanoparticles as a knife that cuts with nanoscale precision. The cutting proceeds via catalytic hydrogenation of the graphene lattice, and can generate graphene pieces with specific zigzag or armchair edges. The size of the nanoparticle dictates the edge structure that is produced during the cutting. The cutting occurs along straight lines and along symmetry lines, defined by angles of 60° or 120°, and is deflected at free edges or defects, allowing practical control of graphene nano-engineering.     

热镀锌过程挡板对镀层均匀性影响的模拟研究

为解决热镀锌过程中常出现的边部过镀锌缺陷,利用数值模拟方法对热镀锌气刀射流喷吹过程进行仿真研究,分析了挡板厚度对带钢边部压力场的影响;并借助镀层厚度计算模型,计算挡板厚度和边部角度对镀层厚度的作用关系;同时通过不同拉钢速度、气刀狭缝总压等工况,对挡板的厚度及边部角度进行优化.结果表明:随挡板厚度减小,带钢边部作用力增大并逐渐接近中心处;带钢边部镀层厚度随挡板厚度的减小而变薄,随挡板边部角度的增加而先减小后增大;挡板厚度2 mm、边部角度90°时,能有效提高带钢横向作用力和镀层分布的均匀性.     

Controllable Dynamic Zigzag Pattern Formation in a Soft Helical Superstructure

Zigzag pattern formation is a common and important phenomenon in nature serving a multitude of purposes. For example, the zigzag‐shaped edge of green leaves boosts the transportation and absorption of nutrients. However, the elucidation of this complicated shape formation is challenging in fluid mechanics and soft condensed matter systems. Herein, a dynamically reconfigurable zigzag pattern deformation of a soft helical superstructure is demonstrated in a photoresponsive self‐organized cholesteric liquid crystal superstructure under the simultaneous influence of an applied electric field and light irradiation. The zigzag‐shaped pattern can not only be generated and terminated repeatedly on demand, but can also be easily manipulated by alternating irradiation of ultraviolet and visible light while under the influence of a sustained electric field. This unique behavior results from a delicate balance among the variable experimental parameters. The evolution of the zigzag‐shaped pattern is successfully modeled by numerical simulations and has been monitored through diffraction of a probe laser. Interestingly, this fascinating zigzag‐shaped pattern yields crescent‐shaped diffraction pattern. The reversibly controllable dynamic zigzag pattern could enable the fabrication of novel photonic devices and architectures, besides greatly advancing the fundamental understanding of temporal behavior of ordered soft materials under combined stimuli.     

One-step and cost-effective synthesis of micrometer-sized saw-like silver nanosheets by oil/water interfacial method

One-step synthesis of silver saw-like nanosheets was introduced by using aqueous AgNO₃ and benzene-soluble p-phenylenediamine (pPD). Based on the X-ray diffraction pattern and selected-area electron diffraction pattern, the silver was single crystal. As indicated by Scanning Electron Microscopy, Transmission Electron Microscopy and the auxiliary characterization by Fourier transform infrared and Raman Spectroscopy, the nanosheets are ~ 20 μm in edge length and are coated by poly(p-phenylenediamine) (PpPD) thin films. The role of oil/water interface and PpPD on the formation of sheet-like morphology was analyzed. This method is facile and cost-effective.     

Crystallization of ZSM-5 zeolite under microgravity

Crystal growth of ZSM-5 zeolite under microgravity was carried out using a Soviet reentry system. The space-grown zeolite was composed of grains of uniform shape and size (ca. 10 μm). Most of zeolite grains were linked with each other by the edge of the grain. The electron diffraction of each grain showed a single-crystal diffraction pattern, indicating the presence of well-crystallized zeolite crystal. The relatively large difference in the surface Al concentration existed between different crystals of the space-grown zeolite, as compared with the zeolite crystals synthesized in the ground with stirring. Based on these results, the crystals growth of zeolite in the microgravity environment was discussed.