检索结果-内蒙古大学图书馆

Conference on current developments in Lens design and optical engineering XV

作者： Prater, Karin Dukwen, Julia Scharf, Toralf Herzig, Hans Peter Hermerschmidt, Andreas Ecole Polytech Fed Lausanne Opt & Photon Technol Lab CH-2000 Neuchatel Switzerland Fraunhofer Inst Prod Technol IPT D-52074 Aachen Germany CHOLOEYE Photon AG D-12489 Berlin Germany

ISBN: (纸本)9781628412192

Glassy carbon is used nowadays for a variety of applications because of its mechanical strength, thermal stability and non-sticking adhesion properties. This makes it also a suitable candidate as mold material for precision compression molding of low and high glass-transition temperature materials. To fabricate molds for diffractive optics a high-resolution structuring technique is needed. We introduce a process that allows the micro-structuring of glassy carbon by reactive ion etching. Key parameters such as uniformity, surface roughness, edge definition and lateral resolution are discussed. They are the most relevant parameters for a stamp in optical applications. The use of titanium as a hard mask makes it possible to achieve a reasonable selectivity of 4:1, which has so far been one of the main problems in micro-structuring of glassy carbon. We investigate the titanium surface structure with its 5-10 nm thick layer of TiO2 grains and its influence on the shape of the hard mask. In our fabrication procedure we were able to realize optically flat diffractive structures with slope angles of more than 80 degrees at typical feature sizes of 5 mu m and at 700 nm depth. The fabricated glassy carbon molds were applied to thermal imprinting onto different glasses. Glassy carbon molds with 1 mm thickness were tested with binary optical structures. Our experiments show the suitability of glassy carbon as molds for cost efficient mass production with a high quality.

关键词： diffractive optical element glass molding glassy carbon reactive ion etching fused silica molding

来源：评论

学校读者我要写书评

暂无评论

design and analysis of an adaptive lens that mimics the performance of the crystalline lens in the human eye 15

Design and analysis of an adaptive lens that mimics the perf...

引用

Conference on current developments in Lens design and optical engineering XV

作者： Santiago-Alvarado, Agustin Cruz-Felix, Angel S. Iturbide-Jimenez, F. Martinez-Lopez, M. Ramirez-Como, M. Armengol-Cruz, V. Vasquez-Baez, I. Mixteca Technol Univ Huajuapan De Leon 69000 Oax Mexico

ISBN: (纸本)9781628412192

Tunable lenses are optical systems that have attracted much attention due to their potential applications in such areas like ophthalmology, machine vision, microscopy and laser processing. In recent years we have been working in the analysis and performance of a liquid-filled variable focal length lens, this is a lens that can modify its focal length by changing the amount of water within it. Nowadays we extend our study to a particular adaptive lens known as solid elastic lens (SEL) that it is formed by an elastic main body made of Polydimethylsiloxane (PDMS Sylgard 184). In this work, we present the design, simulation and analysis of an adaptive solid elastic lens that in principle imitates the accommodation process of the crystalline lens in the human eye. For this work, we have adopted the parameters of the schematic eye model developed in 1985 by Navarro et al.;this model represents the anatomy of the eye as close as possible to reality by predicting an acceptable and accurate quantity of spherical and chromatic aberrations without any shape fitting. An opto-mechanical analysis of the accommodation process of the adaptive lens is presented, by simulating a certain amount of radial force applied onto the SEL using the finite element method with the commercial software SolidWorks (R). We also present ray-trace diagrams of the simulated compression process of the adaptive lens using the commercial software OSLO (R).

关键词： Solid elastic lens tunable lens crystalline lens PDMS

来源：评论

学校读者我要写书评

暂无评论

Organic photovoltaics: key photophysical, device and design aspects

引用

JOURNAL OF MODERN OPTICS 2014年第21期61卷 1703-1713页

作者： Joshi, Dhruv Shivanna, Ravichandran Narayan, K. S. Indian Inst Sci Jawaharlal Nehru Ctr Adv Sci Res Chem & Phys Mat Unit Bangalore 560012 Karnataka India

Key aspects of Organic Photovoltaics (OPVs) have been reviewed in this tutorial. Issues pertaining to the choice of materials, fabrication processes, photophysical mechanisms, device characterization, morphology of active layers and manufacturing are discussed. Special emphasis has been given to recent developments in large-area modules. current strategies in enhancing the performance using external optical engineering approaches have also been highlighted. OPVs as a technology combine low weight, flexibility, low cost, good form factor and high-throughput processing;making them a promising PV technology for the future.

关键词： organic photovoltaics photonics printed solar cells

来源：评论

学校读者我要写书评

暂无评论

Research on chromatic properties of high order kinoform 15

Research on chromatic properties of high order kinoform

引用

Conference on current developments in Lens design and optical engineering XV

作者： Wegrzynska, K. Rachon, M. Doch, M. Siemion, A. Suszek, J. Kolodziejczyk, A. Sypek, M. Warsaw Univ Technol Fac Phys PL-00662 Warsaw Poland

ISBN: (纸本)9781628412192

This work is dedicated to the evaluation of the chromatic properties of high order kinoforms. Typical kinoform (of the first order) is a phase only structure having the phase retardation varying in the range 0-2 pi. Such structures are very commonly used in many practical applications for different ranges of electromagnetic radiation like ultraviolet, visible, infrared, terahertz and millimeter waves. Besides those benefits such structures have one crucial disadvantage - they suffer from big chromatic aberration. This limits their practical application only to the narrowband work, where main wavelength must be well defined (Delta lambda/lambda<<1). This paper presents other type of diffractive structures called high order kinoforms (HOK). They exhibit phase retardation of n2 pi, where n is an integer number much bigger than 1. Due to this fact they are relatively thin and therefore can be manufactured using laser lithography in thick photoresist (deeply etched). On the other hand they are thick enough to suppress chromatic aberrations. In comparison to the well-known Fresnel lens, the high order kinoform structure has precisely controlled phase retardation between different zones. In the case of the Fresnel lens (known from XViii/XIX century), phase retardations between different zones are random (designing process is based on the geometrical optics). In the case of the high order kinoform working as the spherical lens - taking into account the real size of the detector - it can be shown that the most of the energy being focused in the focal spot will be registered by the detector for different wavelengths. The paper presents simple theoretical considerations, numerical modeling and their experimental evaluation.

关键词： diffractive optics kinoform higher order kinoform chromatic aberration optical elements

来源：评论

学校读者我要写书评

暂无评论

Mu and epsilon near zero metamaterials for perfect coherence and new antenna designs

引用

OPTICS EXPRESS 2014年第8期22卷 9107-9114页

作者： Yang, Jing Jing Francescato, Yan Maier, Stefan A. Mao, Fuchun Huang, Ming Yunnan Univ Wireless Innovat Lab Kunming 65009 Peoples R China Univ London Imperial Coll Sci Technol & Med Blackett Lab London SW7 2AZ England

Wave interference is a fundamental physical phenomenon. Traditionally, the coherent effect of two identical point sources only takes place when the optical path is an integer number of wavelengths. In this paper, we show that mu and epsilon near zero (MENZ) metamaterials can be used to realize a perfectly constructive and isotropic interference. No matter how many point sources are embedded in the MENZ region, the wavefronts overlap perfectly. This translates into a total relaxation of the conventional condition for coherence enabled by the apparent infinite wavelength of the fields within MENZ metamaterials. Furthermore, we investigate crucial parameters such as the shape and size of the MENZ region. We demonstrate that flat sided geometries give rise to constructive interference beams serving as a powerful design mean. We also reveal the importance of relying on deeply sub-wavelength MENZ volumes as larger sizes increase the impedance and therefore reduce the output power of the device. The proposed concepts bear significance for current trends in antenna design which are inspired by the recent developments of electromagnetic metamaterials. Moreover, the perfect coherence effect can be appealing for power combiners, especially in the terahertz where sources are dim, as the irradiation intensity scales with the square of the number of embedded sources. (C) 2014 optical Society of America

关键词： Constructive interference Invisibility cloaks Light transmission optical metamaterials Transformation optics Wave propagation

来源：评论

学校读者我要写书评

暂无评论

design of sub-wavelength dielectric antireflective grading for multijunction concentrator photovolatics

Design of sub-wavelength dielectric antireflective grading f...

引用

Conference on Physics, Simulation, and Photonic engineering of Photovoltaic Devices iii

作者： Wang, Wei Freundlich, Alex Univ Houston Ctr Adv Mat Photovolta & Nanostruct Lab Houston TX 77204 USA

ISBN: (纸本)9780819498946

In iii-V concentrator applications, sunlight is focused with wide angular distribution that limits the effectiveness of conventional thin-film AR coatings. Furthermore the transmission properties are generally degraded non-uniformly over the electromagnetic spectrum, which in the case of multi-junction solar cells leads to additional sub-cell current matching related losses. Here, and in an attempt to identify a better alternative to the conventional planar layer ARCs for iii-V multi-junction concentrator cells in case of with/without protective cover glass in conjunction with wide optical aperture angles, a systematic analysis of design parameters and angular dependent antireflective properties of dielectric gratings has been undertaken, through the implementation of sub-wavelength 2D pyramidal gratings of ZnS and TiO2. The study indicated limited improvement for devices operated with SiO2 like cover glass. In the absence of SiO2 like cover glass, the evaluation indicated that reflection-loss related current losses can be reduced by 2-3 fold compared to their double-layer ARC counterparts. i.e. for a 3J metamorphic device this lead to a current improvement of 0.7 mA/cm(2) per concentration for a 60 degree aperture angles

关键词： angular tolerance antireflective concentrated photovoltaic dielectric effective medium approach iii-V solar cell subwavelength texture

来源：评论

学校读者我要写书评

暂无评论

Making the CHARA Array, Part iii: engineering decisions. To build or not to build 4

Making the CHARA Array, Part III: Engineering decisions. To ...

引用

optical and Infrared Interferometry IV

作者： Ten Brummelaar, Theo A. McAlister, Harold A. Ridgway, Stephen CHARA Array P.O. Box 48 Mt WilsonCA91023 United States CHARA Georgia State University AtlantaGA30303-3083 United States National Optical Astronomy Observatory TucsonAZ85719 United States

ISBN: (纸本)9780819496140

The CHARA Array has been a PI led, low budget, and low manpower operation, and has followed a fairly unconventional path in its development. In this, the third paper of a series of three, we discuss some of the engineering and design decisions made along the way, some right and some wrong, with a focus on the choice between in-house development and the purchase of pre-built, or sub-contracted, subsystems. Along with these issues we will also address a few parts of the system that we might have done differently given our current knowledge, and those that somehow turned out very well. © 2014 SPIE.

关键词： Budget control

来源：评论

学校读者我要写书评

暂无评论

Proof-of-concept demonstration of a miniaturized multi-resolution refocusing imaging system using an electrically tunable lens 15

Proof-of-concept demonstration of a miniaturized multi-resol...

引用

Conference on current developments in Lens design and optical engineering XV

作者： Smeesters, L. Belay, G. Y. Ottevaere, H. Meuret, Y. Vervaeke, M. Van Erps, J. Thienpont, H. Vrije Univ Brussel Fac Engn Dept Appl Phys & Photon TONA Brussels Photon Team B PHOT B-1050 Brussels Belgium

ISBN: (纸本)9781628412192

Refocusing multi-channel imaging systems are nowadays commercially available only in bulky and expensive designs. Compact wafer-level multi-channel imaging systems have until now only been published without refocusing mechanisms, since classical refocusing concepts could not be integrated in a miniaturized configuration. This lack of refocusing capabilities limits the depth-of-field of these imaging designs and therefore their application in practical systems. We designed and characterized a wafer-level two-channel multi-resolution refocusing imaging system, based on an electrically tunable liquid lens and a design that can be realized with wafer-level mass-manufacturing techniques. One wide field-of-view channel (2x40 degrees) gives a general image of the surroundings with a lower angular resolution (0.078 degrees), whereas the high angular resolution channel (0.0098 degrees) provides a detailed image of a small region of interest with a much narrower field-of-view (2x7.57 degrees). The latter high resolution imaging channel contains the tunable lens and therefore the refocusing capability. The performances of this high resolution imaging channel were experimentally characterized in a proof-of-concept demonstrator. The experimental and simulated depth-of-field and resolving power correspond well. Moreover, we are able to obtain a depth-of-field from 0.25m until infinity, which is a significant improvement of the current state-of-the-art static multi-channel imaging systems, which show a depth-of-field from 9m until infinity. Both the high resolution and wide field-of-view imaging channels show a diffraction-limited image quality. The designed wafer-level two-channel imaging system can form the basis of an advanced three-dimensional stacked image sensor, where different image processing algorithms can be simultaneously applied to the different images on the image sensor.

关键词： lens system design adaptive optics tunable lens refocusing imaging systems modulation transfer function miniature camera optics proof-of-concept demonstration

来源：评论

学校读者我要写书评

暂无评论

Materials science and design for germanium monolithic light source on silicon

Materials science and design for germanium monolithic light ...

引用

作者： Cai, Yan Massachusetts Institute of Technology

学位级别：博士

Germanium (Ge) is an optically active material with the advantages of Si-CMOS compatibility and monolithic integration. It has great potential to be used as the light emitter for Si photonics. Tensile strain and n-type doping are two key properties in Ge to achieve optical gain. This thesis mainly focuses on: (1) physical understandings of the threshold behavior of Ge-on-Si bulk laser and the temperature dependent performance; (2) process developments to grow and planarize the epitaxial Ge on Si in oxide trenches and corners; (3) introduction of n-type dopant into Ge-on-Si thin films while studying the threading dislocation behavior in n-Ge during annealing; (4) design an external cavity Ge laser integrated with Si waveguides for a low threshold current and single mode operation. Heavy n-type doping was observed to change the Ge electronic band structure by band gap narrowing effect. We also found a failure of using a simple Drude model to explain free carrier absorption in n-Ge. We modified the optical gain simulation based on the above two observations in Ge. We found a broad gain bandwidth of ~ 200 nm from 1550 nm to 1750 nm and a higher net materials gain. We predicted a theoretical lasing threshold current density of 5~10 kA/cm² in the bulk Ge laser device with the n-type doping of mid-10¹⁹ cm-³ at room temperature. We also predicted the Ge laser device would have better temperature stability regarding the threshold current compared to the iii-V laser. Single crystalline Ge was epitaxial grown on Si in oxide trenches using ultra high vacuum chemical vapor deposition. The selective growth lead to the faceting in Ge because of the different growth rates of crystal orientations. We developed a suitable photolithography and oxide etch process to get the vertical oxide sidewall for Ge trench filling. We also tested the Ge growth in the T-shape corners to improve the reflectivity at the waveguide end. The T-shape structure was also useful for the Ge/Si waveguide coup

关键词： Materials Science and engineering

来源：评论

学校读者我要写书评

暂无评论

Microcontrollers and optical Sensors for Education in Optics and Photonics 3

Microcontrollers and Optical Sensors for Education in Optics...

引用

3rd Conference on Optics Education and Outreach

作者： Dressler, Paul Wielage, Heinz Haiss, Ulrich Vauderwange, Oliver Wozniak, P. Curticapean, Dan Offenburg Univ D-77652 Offenburg Germany

ISBN: (纸本)9781628412154

The digital revolution is going full steam ahead, with a constantly growing number of new devices providing a steady increase in complexity and power. Most of the success is based on one important invention: the microprocessor/microcontroller. In this paper the authors present how to integrate microcontrollers and optical sensors in the curricula of media engineering by combining subjects of media technology, optics, information technology and media design. Hereby the aim is not to teach these topics separate from each other, but to bring them together in interdisciplinary lectures, projects and applications. Microcontrollers can be applied in various ways to teach content from the fields of optics and photonics. They can be used to control LEDs, displays, light detectors and infrared sensors, which makes it possible to build measuring instruments like e.g. a lux meter, a light barrier or an optical distance meter. The learning goals are to stimulate the student's interest in the multiplicity of subjects related to this course and to support a deeper understanding of the close connections between them. The teaching method that the authors describe in their paper turned out to be very successful, as the participants are motivated to bring in their own ideas for projects, they spend more time than requested and as many students return to the courses as tutors. It is an example for effectual knowledge transfer and exchange of ideas among students.

关键词： Microcontrollers Sensors Computer programming Light emitting diodes optical sensors Infrared sensors Analog electronics Photonics Information technology Voltage controlled current source

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：