scholarly journals Optical and Reflective Characteristics Measurement and Focal Length Calculation of a Hollow Tetrahedral Corner and a Solid Highly Retroreflective Cubes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Mohammad Saeed Marouf
Keyword(s):  
Surface Quality ◽  
Focal Length ◽  
Optical Devices ◽  
Corner Cube ◽  
Optical Tools ◽  
Surface Flatness ◽  
Corner Cubes

Corner cubes are one of the most important optical tools used in new optical devices and optical LIDAR. This paper compares two different designs of the hollow and solid tetrahedral corner cubes and determines the relation between the Retroreflection index and the surface quality N and the surface flatness ∆N and its effect on the focal length of the hollow and solid corner cube.

scholarly journals ECE/SAE Dual Functional SuperPin Plus Curved Reflex Reflector by Use of New Structured Corner Cubes

2020 ◽  
Vol 10 (2) ◽  
pp. 454
Author(s):  
Hien-Thanh Le ◽  
Lanh-Thanh Le ◽  
Ming-Jui Chen ◽  
Thanh-Hong Lam ◽  
Hsing-Yuan Liao ◽  
...  
Keyword(s):  
Genetic Algorithms ◽  
Dihedral Angle ◽  
Manufacturing Costs ◽  
Corner Cube ◽  
Dual Functional ◽  
Economic Commission ◽  
The Us ◽  
The Eu ◽  
Building Elements ◽  
Corner Cubes

We propose and demonstrate, using optical experiments, a new reflex reflector structure called SuperPin Plus. The structure is composed of special pin groups with dihedral-angle offsets in corner cubes. One of the specular features brought by this new design is that it can comply with both the US SAE (US Society of Automotive Engineers) standard and the EU ECE (Economic Commission for Europe) standard, so that manufacturing costs of reflex reflector for both European and American automobile markets can be reduced. By using genetic algorithms for optimization, the angles and the positions of the pins, which are the building elements of corner cube reflectors, serve as the parameters to tune up the performance of the SuperPin Plus curved reflex reflector. Compared with conventional ECE flat regular retro-reflectors, we found that not only can we achieve a 41% higher retro-reflection efficiency with the ECE SuperPin Plus flat reflex reflector, but that SuperPin Plus can also act as a reflex reflector within SAE standards. In addition, we demonstrate that the retro-reflection efficiency is 30.5% higher (SAE standard) and 42.7% higher (ECE standard), and that a 32% increase in working area can be achieved if double pin groups are used to construct the corner cubes instead of a single pin arrangement, in a curved SuperPin Plus reflex reflector.

Design of the Real-Time Autofocusing System for Collimator with Long Focus Length and Large Aperture

2011 ◽  
Vol 127 ◽  
pp. 25-31
Author(s):  
Xiang Li ◽  
Xiao Hui Zhang
Keyword(s):  
Computer Simulation ◽  
Semiconductor Lasers ◽  
Essential Role ◽  
Focal Length ◽  
Optical Devices ◽  
Plane Mirror ◽  
Large Aperture ◽  
Surrounding Environment ◽  
New Type ◽  
Common Problems

Large aperture collimator which has been widely used for calibrating and testing various optical devices plays an essential role in correlative laboratories. As being the basic testing and calibration equipment, the large aperture collimator’s accuracy should be much higher than the device under testing in order to ensure the accuracy of the measurement. However, the process of adjusting the collimator is extremely complicated due to the collimator’s large aperture and long focal length. So it is difficult to ensure the measurement’s quality and easy to cause the system being vulnerable to the surrounding environment. One of the most common problems is defocus. In order to solve the problem above, this issue presents a new type of autocollimator autofocusing system which uses pentaprism instead of using large-aperture plane mirror, semiconductor lasers as light source and CCD sensor as receiver. The system is smaller, lighter, and more convenient when using. The computer simulation shows that the autofocusing system’s resolution could reach the accuracy of 40μm. If we use the relevant algorithms to execute the sub-pixel scanning, the resolution could reach the accuracy of 10μm. It shows that the system could satisfy the required testing precision of testing large aperture optical device.

scholarly journals АВТОМАТИЗИРОВАННАЯ ОЦЕНКА ПОВЕРХНОСТНОЙ ПОРИСТОСТИ БЕТОННЫХ ИЗДЕЛИЙ

2020 ◽  
Author(s):  
N. Dimitriadi
Keyword(s):  
Surface Quality ◽  
Focal Length ◽  
Evaluation Process ◽  
Normative Document ◽  
Surface Porosity ◽  
Photographic Recording ◽  
Calculation Results ◽  
Speed Up ◽  
The Republic ◽  
Special Stand

Currently in the territory of the Republic of Belarus the normative document is used in order to evaluate the surface of concrete and reinforced concrete products and constructions [1]. According to this normative document concrete surfaces of the constructions are divided into 7 categories from A1 to A7. The author suggests that the methods for evaluation of the surface quality, specified in [1], are not sufficient. Wherefore, the article reflects the works performed on development of the installation, methods and program to determine the surface porosity of concrete products. It describes the method to determine a particular and integral surface porosity through receipt and processing of the digital image with the developed program. It allows to automate the evaluation process of the surface and significantly speed up it (especially, in case of a great number of pores on the studied surface). The installation for receipt of the sample contrast images was developed, the modes for images photographic recording were selected. This installation for photographic recording used CANON EOS 1100D camera, on a special stand, used to maintain a constancy of focal length and distance to the registered object. VBA based program was developed, it allows to determine the pores size and their distribution, calculate their number and evaluate the form, and also allows to determine particular porosity for concrete diameters and integral porosity. The obtained value of the integral porosity can be used for a clarified calculation of the relative and absolute adhesion value when developing compositions of the release agents. Based on the obtained calculation results it is possible to plot a graph of the pores distribution that formalise and simplifies the aim of the surface quality evaluation. В настоящее время на территории Республики Беларусь при оценке поверхности бетонных и железобетонных изделий и конструкций пользуются нормативным документом [1]. Согласно данному нормативному документу бетонные поверхности конструкций разделены на 7 категорий от А1 до А7. Автором высказано мнение о недостаточности методов оценки качества поверхности, изложенных в [1], в связи с чем в статье отражены выполненные работы по разработке установки, методики и программы для определения поверхностной пористости бетонных изделий. Приведена методика определения частной и интегральной поверхностной пористости посредством получения и обработки цифрового изображения разработанной программой. Она позволяет автоматизировать процесс оценки поверхности и значительно ускорить процесс оценки (особенно в случае большого количества пор на исследуемой поверхности). Разработана установка для получения контрастных изображений образцов, подобраны режимы фоторегистрации изображений. В данной установке для фоторегистрации использовался фотоаппарат CANON EOS 1100D, на специальной стойке, служащей для обеспечения постоянства фокусного расстояния и расстояния до регистрируемого объекта. Разработана программа на основе VBA, позволяющая вычислять: размеры пор, их распределение, подсчитать их количество и оценить форму, также позволяет вычислить частную пористость для конкретных диаметров и интегральную пористость. Полученное значение интегральной пористости может быть использовано для уточненного вычисления величины относительной и абсолютной адгезии при разработке составов разделительных смазок. На основе получаемых результатов вычислений возможно построение графиков распределения пор, что формализует и упрощает задачу оценки качества поверхности.

Effect of Defocus Distance on Layer Quality in Insider-Laser Coaxial Powder Feeding Laser Cladding

2011 ◽  
Vol 287-290 ◽  
pp. 2419-2422
Author(s):  
Hou Shun Sun ◽  
Shi Hong Shi ◽  
Ge Yan Fu ◽  
Jia Zhang ◽  
Chen Wang ◽  
...  
Keyword(s):  
Surface Quality ◽  
Laser Cladding ◽  
Process Parameters ◽  
High Ratio ◽  
Metal Part ◽  
Laser Cladding Process ◽  
Surface Flatness ◽  
Powder Feeding

Insider-laser coaxial powder feeding laser cladding is one kind of technique, which can be used in metal part directly manufacturing field. Compared with outsider-laser coaxial powder feeding laser cladding techniques, it has significant advantages [1]. In order to research the effect of defocus distance on the layer quality in insider-laser coaxial powder feeding laser cladding, it has taken some expriments in this paper to study the layer quality by constantly changing the defocus distance, with other laser cladding process parameters invariable. In addition, this paper measues, analysis the cladding layer’s width, height, the surface quality (including surface flatness, flat-wide ratio and flat-high ratio [2]), hardness and microstructure, then summarizes the effect of the defocus distance on the layer quality in this paper.

Effect of layer thickness on the overhanging surface quality manufactured by selective laser melting

2021 ◽  
pp. 095440622110528
Author(s):  
Weipeng Duan ◽  
Meiping Wu ◽  
Jitai Han ◽  
Yiqing Ma ◽  
Xiaojin Miao
Keyword(s):  
Experimental Data ◽  
Optimal Condition ◽  
Layer Thickness ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Laser Melting ◽  
Surface Flatness ◽  
Increasing Demand ◽  
The Relationship

With the increasing demand for the precision of lightweight part, overhanging surface quality has attracted more and more attentions in recent years. In this work, the relationship between overhanging surface quality and layer thickness was studied. The testing results revealed that with the increasing of the layer thickness, surface quality, especially the surface flatness, showed a significant decreasing trend due to the decreasing of the bending deformation. When layer thickness was ranged from 0.15 to 0.18, it reached a relative optimal condition while the sinking distance and flatness within 0.095 mm–0.1 mm and 0.076 mm–0.078 mm, respectively. With the further increasing of the layer thickness, both sinking distance and surface flatness had a quite significant decreasing due to the increasing gravity of the overhanging layer powder and bonded powder caused by the molten pool sinking. Combined to the experimental data and the analysis given above, the structure of the overhanging surface was optimized and the surface quality showed a further increase.

Looking for an Artificial Eye: On the Borderline between Painting and Topography

2005 ◽  
Vol 10 (2) ◽  
pp. 263-286
Author(s):  
Filippo Camerota
Keyword(s):  
Sixteenth Century ◽  
Fifteenth Century ◽  
Optical Devices ◽  
Linear Perspective ◽  
Artificial Eye ◽  
Optical Tools ◽  
Documentary History ◽  
History Of ◽  
David Hockney ◽  
Almost All

AbstractThe use of instruments for drawing from life is documented since the fifteenth century in a variety of books, drawings and actual devices. Almost all of the instruments invented for this purpose belong to the linear perspective tradition, being conceived as mechanical expressions of a geometric principle, namely the intersection of the visual pyramid. On the basis of a close but controversial analysis of some important paintings of the early Renaissance, David Hockney and Charles Falco have concluded to a widespread use of optical devices in painters' workshops, such as concave mirrors, convex lenses and camera obscuras. Devices of this kind were generally used by optics scholars in their experiments with light and the multiplication of species. However, except for some isolated references to the camera obscura and flat mirrors,1 the documentary history of art is completely silent about the use of these optical tools by painters. Written evidence, in this sense, can be found only in the late sixteenth century but related to map-making more than to painting. Moreover, growing interest in such devices is only evident in connection with the invention of the telescope and its interpretation as an "artificial eye."2

Geometric Tolerance Verification - Innovative Evaluation of Facade Surface Flatness Using TLS (Terrestrial Laser Scanning)

2016 ◽  
Vol 820 ◽  
pp. 81-89
Author(s):  
Tomas Funtik ◽  
Marek Dubek ◽  
Jan Erdelyi
Keyword(s):  
Surface Quality ◽  
Relative Position ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
National Standards ◽  
Geometric Tolerance ◽  
Surface Flatness ◽  
Tolerance Verification ◽  
Manual Verification

This article assesses the application of TLS when evaluating the façade surface flatness on finished facade. Current methods of geometrical tolerance verification are reviewed and the results are compared data obtained from point clouds (using TLS).The process of currently used methods consist of manual verification of flatness by spirit level in accordance with national standards, which specifies exact places to be assessed and the number of measurements. With TLS technology we assess the surface quality and flatness more precisely, faster and moreover, investigate 100% of area. This may lead to better evaluation of the relative position of investigated areas, points and constructions. However, a further investigation, which would define the methodology for evaluation the geometric tolerance from point clouds is needed.

Optical testing of the surface quality of a variable focal length lens with null-screens

2011 ◽  
Author(s):  
Manuel Campos-García ◽  
Agustín Santiago-Alvarado ◽  
Víctor Iván Moreno-Oliva ◽  
Rufino Díaz-Uribe
Keyword(s):  
Surface Quality ◽  
Focal Length ◽  
Optical Testing ◽  
Focal Length Lens

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

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