Готові списки джерел за темами / Flat-convex lens

Добірка наукової літератури з теми "Flat-convex lens"

Автор: Grafiati

Опубліковано: 30 травня 2022

Оновлено: 31 травня 2022

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Статті в журналах з теми "Flat-convex lens"

Schwarz, J., M. Ramsey, D. Headley, P. Rambo, I. Smith, and J. Porter. "Thermal lens compensation by convex deformation of a flat mirror with variable annular force." Applied Physics B 82, no. 2 (December 15, 2005): 275–81. http://dx.doi.org/10.1007/s00340-005-2033-9.

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Lingasamy, Veluchamy, and Krishnasamy T. Selvan. "A comparison of planar convex dielectric lens loaded flat reflector with parabolic reflector and reflectarray." Microwave and Optical Technology Letters 61, no. 11 (June 28, 2019): 2500–2505. http://dx.doi.org/10.1002/mop.31927.

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Wang, Pan, Ya-Zhou Wang, Da-Hai Li, Huan Deng, and Qiong-Hua Wang. "P-83: Large Depth Integral Imaging Using Piano-Convex Micro-Lens Array and Flat-Panel Array." SID Symposium Digest of Technical Papers 45, no. 1 (June 2014): 1295–97. http://dx.doi.org/10.1002/j.2168-0159.2014.tb00339.x.

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Wang, Pan, Qiong-Hua Wang, Ya-Zhou Wang, and Da-Hai Li. "Depth-enhanced integral imaging display based on plano-convex micro-lens array and flat-panel array." Optik 126, no. 24 (December 2015): 5744–47. http://dx.doi.org/10.1016/j.ijleo.2015.09.084.

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Jang, Hyuk Jae, Yeong Jae Kim, Young Jin Yoo, Gil Ju Lee, Min Seok Kim, Ki Soo Chang, and Young Min Song. "Double-Sided Anti-Reflection Nanostructures on Optical Convex Lenses for Imaging Applications." Coatings 9, no. 6 (June 21, 2019): 404. http://dx.doi.org/10.3390/coatings9060404.

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Anti-reflection coatings (ARCs) from the cornea nipple array of the moth-eye remarkably suppress the Fresnel reflection at the interface in broadband wavelength ranges. ARCs on flat glass have been studied to enhance the optical transmittance. However, little research on the implementation of ARCs on curved optical lenses, which are the core element in imaging devices, has been reported. Here, we report double-sided, bio-inspired ARCs on bi-convex lenses with high uniformity. We theoretically optimize the nanostructure geometry, such as the height, period, and morphology, since an anti-reflection property results from the gradually changed effective refractive index by the geometry of nanostructures. In an experiment, the transmittance of an ARCs lens increases up to 10% for a broadband spectrum without distortion in spot size and focal length. Moreover, we demonstrate ~30% improved transmittance of an imaging system composed of three bi-convex lenses, in series with double-sided ARCs (DARCs).

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Li, Hongliang, Changyi Zhou, Woo-Bin Lee, Duk-Yong Choi, and Sang-Shin Lee. "Flat telescope based on an all-dielectric metasurface doublet enabling polarization-controllable enhanced beam steering." Nanophotonics 11, no. 2 (December 8, 2021): 405–13. http://dx.doi.org/10.1515/nanoph-2021-0609.

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Abstract A flat telescope (FTS), which incorporates an all-dielectric metasurface doublet (MD) based on hydrogenated amorphous silicon nanoposts, is proposed and demonstrated to achieve flexibly magnified angular beam steering that is sensitive to both light polarization and deflection direction. Specifically, for transverse-electric-polarized incident beams, the MD exhibits deflection magnification factors of +5 and +2, while for transverse magnetic polarization, the beam is steered in reverse to yield magnification factors of −5 and −2 in the horizontal and vertical directions, respectively. The proposed MD comprises cascaded metalenses, which can invoke polarization-selective transmission phases. The MD which emulates a set of convex and concave lenses renders positively increased beam deflection, whereas the case corresponding to a pair of convex lenses facilitates negatively amplified beam deflection. The essential phase profiles required for embodying the MD are efficiently extracted from its geometric lens counterpart. Furthermore, the implemented FTS, operating in the vicinity of a 1550 nm wavelength, can successfully enable enhanced beam steering by facilitating polarization-sensitive bidirectional deflection amplifications. The proposed FTS can be applied in the development of a miniaturized light detection and ranging system, where the beam scanning range can be effectively expanded in two dimensions.

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Mirbagheri, Mahya, Naser Hakimi, Elias Ebrahimzadeh, and S. Kamaledin Setarehdan. "Simulation and in vivo investigation of light-emitting diode, near infrared Gaussian beam profiles." Journal of Near Infrared Spectroscopy 28, no. 1 (November 1, 2019): 37–50. http://dx.doi.org/10.1177/0967033519884209.

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Near infrared spectroscopy is an optical imaging technique which offers a non-invasive, portable, and low-cost method for continuously measuring the oxygenation of tissues. In particular, it can provide the brain activation through measuring the blood oxygenation and blood volume in the cortex. Understanding and then improving the spatial and depth sensitivity of near infrared spectroscopy measurements to brain tissue are essential for designing experiments as well as interpreting research findings. In this study, we investigate the effect of applying two common light beam profiles including Uniform and Gaussian on the penetration depth of an LED-based near infrared spectroscopy. In this regard, two Gaussian profiles were produced by adjusting plano-convex and bi-convex lenses and the Uniform profile was provided by applying a flat lens. Two experiments were conducted in this study. First, a simulation experiment was carried out based on scanning the intra space of a liquid phantom by using static and pulsating absorbers to compare the penetration depth of the configurations applied on the LED-based near infrared spectroscopy with that of a laser-based near infrared spectroscopy. Second, to show the feasibility of the best proposed configuration applied, an in vivo experiment of stress assessment has been performed and its results have been compared with that results obtained by laser one. The results showed that the LED-based near infrared spectroscopy equipped with bi-convex lens provides a penetration depth and hence quality measurements of near infrared spectroscopy and its extracted heart rate variability signals as well as laser-based near infrared spectroscopy especially in the application of stress assessment.

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Zampighi, G. A., J. E. Hall, G. R. Ehring, and S. A. Simon. "The structural organization and protein composition of lens fiber junctions." Journal of Cell Biology 108, no. 6 (June 1, 1989): 2255–75. http://dx.doi.org/10.1083/jcb.108.6.2255.

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The structural organization and protein composition of lens fiber junctions isolated from adult bovine and calf lenses were studied using combined electron microscopy, immunolocalization with monoclonal and polyclonal anti-MIP and anti-MP70 (two putative gap junction-forming proteins), and freeze-fracture and label-fracture methods. The major intrinsic protein of lens plasma membranes (MIP) was localized in single membranes and in an extensive network of junctions having flat and undulating surface topologies. In wavy junctions, polyclonal and monoclonal anti-MIPs labeled only the cytoplasmic surface of the convex membrane of the junction. Label-fracture experiments demonstrated that the convex membrane contained MIP arranged in tetragonal arrays 6-7 nm in unit cell dimension. The apposing concave membrane of the junction displayed fracture faces without intramembrane particles or pits. Therefore, wavy junctions are asymmetric structures composed of MIP crystals abutted against particle-free membranes. In thin junctions, anti-MIP labeled the cytoplasmic surfaces of both apposing membranes with varying degrees of asymmetry. In thin junctions, MIP was found organized in both small clusters and single membranes. These small clusters also abut against particle-free apposing membranes, probably in a staggered or checkerboard pattern. Thus, the structure of thin and wavy junctions differed only in the extent of crystallization of MIP, a property that can explain why this protein can produce two different antibody-labeling patterns. A conclusion of this study is that wavy and thin junctions do not contain coaxially aligned channels, and, in these junctions, MIP is unlikely to form gap junction-like channels. We suggest MIP may behave as an intercellular adhesion protein which can also act as a volume-regulating channel to collapse the lens extracellular space. Junctions constructed of MP70 have a wider overall thickness (18-20 nm) and are abundant in the cortical regions of the lens. A monoclonal antibody raised against this protein labeled these thicker junctions on the cytoplasmic surfaces of both apposing membranes. Thick junctions also contained isolated clusters of MIP inside the plaques of MP70. The role of thick junctions in lens physiology remains to be determined.

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Торопов, М. Н., А. А. Ахсахалян, И. В. Малышев, М. С. Михайленко, А. Е. Пестов, Н. Н. Салащенко, А. К. Чернышов та Н. И. Чхало. "Линзовый корректор волнового фронта для изучения плоских поверхностей". Журнал технической физики 91, № 10 (2021): 1583. http://dx.doi.org/10.21883/jtf.2021.10.51374.108-21.

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The method of manufacturing and the results of studies of a lens corrector that converts a spherical diverging front into a plane one and is intended for studying flat surfaces as part of an interferometer with a diffraction comparison wave is described. A feature of the corrector is the use of an aspherical convex surface with a maximum deviation of ∼200 μm from the nearest sphere. The first experimental results are presented, indicating the prospects for using ion-beam processing to improve the quality of the wavefront. After the procedure of ion-beam processing, the aberrations over the entire aperture of the corrector decreased by more than 4 times and amounted to the parameter of the height difference PV = 207 nm (∼λ/3) and RMS = 19.2 nm (∼λ /33). On an area with a diameter of 80%, the aberrations fell to the nanometer level: PV = 65 nm (∼λ/10) and RMS = 8.3 nm (∼λ/76).

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Illarionov, A. I., and M. S. Ivanov. "Effect of the geometry of the aberration focusing of a convex-flat lens on the angular parameters of the second optical harmonic." Bulletin of the Russian Academy of Sciences: Physics 81, no. 9 (September 2017): 1136–40. http://dx.doi.org/10.3103/s1062873817090118.

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Більше джерел

Дисертації з теми "Flat-convex lens"

Чорний, Владислав Олександрович. "Лазерний вимірювач швидкості кровотоку". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/43661.

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Обсяг звіту становить 56 сторінок, міститься 25 ілюстрацій, 17 таблиці. Загалом опрацьовано 22 джерел. Актуальність: контроль та швидка оцінка характеристик параметрів кровотоку є важливим атрибутом правильної діагностики пацієнта, а в особливості неівазивним методом вимірювання, так як сприйняття організму чужорідного тіла може вести до неприємних наслідків. Мета: недорогий та надійний лазерний вимірювач швидкості кровотока, як для лабораторних дослідів, так і для повсякденного контролю пацієнта. Завдання: 1. Огляд та аналіз літератури, що стосується лазерних вимірювачів швидкості кровотоку. 2. Огляд та аналіз інтелектуальної власності сучасних лазерних вимірювачів швидкості кровотоку. 3. Побудова оптично-функціональної схеми приладу. 4. Підбір елементів для реалізації швидкоміра. 5. Моделювання лазерного вимірювача кровотоку.
The volume of the report is 56 pages, contains 25 illustrations, 17 tables. In general, 22 sources were processed. Relevance: control and rapid assessment of the characteristics of blood flow parameters is an important attribute of proper diagnosis of the patient, and in particular a non-invasive method of measurement, as the perception of a foreign body can lead to unpleasant consequences. Purpose: inexpensive and reliable laser blood flow meter, both for laboratory experiments and for daily monitoring of the patient. Task: 1. Review and analysis of the literature related to laser blood flow meters. 2. Review and analysis of intellectual property of modern laser blood flow meters. 3. Construction of the optical-functional scheme of the device. 4. Selection of elements to the optical-functional scheme of the flowmeter. 5. Simulation of a laser blood flow meter.

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Wong, Cheng Jhang, and 翁澄璋. "A Study of the Uniformity of LED lighting with Flat-Convex Lens." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/nzudsf.

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碩士
崑山科技大學
機械工程研究所
96
This paper use TracePro optical simulation software to simulate three LED light source with the domed acrylic (PMMA) as a lens to a virtual light source. General lamp and simulated work environment to play in the optical absorption screen, the LED light source and by adjusting the distance between the lens and light source. Simulation different results show that the average illumination is about 522 lux, the uniformity is about that satisfies the CNS regulations.

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Книги з теми "Flat-convex lens"

Escudier, Marcel. Oblique shockwaves and expansion fans. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198719878.003.0012.

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External supersonic gas flow in which changes in the fluid and flow properties are brought about by direction change is analysed in this chapter. In addition, it is shown that flow over a corner between two flat surfaces resulted in an oblique shockwave if the angle between the two surfaces is less than 180° (a concave corner). The analysis of flow through an oblique shockwave is based upon the superposition of the flowfield for a normal shock onto a uniform flow parallel to the shock. It is also shown that both weak and strong oblique shocks can occur. For an angle in excess of 180° (a convex corner), the flow is turned through an isentropic Prandtl-Meyer expansion fan. Analysis of a Prandtl-Meyer expansion fan starts from consideration of an infinitesimal flow deflection through a Mach wave.

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Тези доповідей конференцій з теми "Flat-convex lens"

Benhacine, Adra, Zoubir Nemouchi, Lyes Khezzar, and Nabil Kharoua. "Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89211.

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A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

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Lewis, Jonathan, Salman Pervaiz, and Sathish Kannan. "A Numerical Study to Investigate Machining Aspects of Convex Surface Drilling." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73672.

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Abstract Metallic alloys with convex curved surfaces have large scale applications in several industries such as in the automotive, marine and aerospace industries. These curved surfaces are used in the applications where surface integrity is extremely important. A large amount of research has been conducted related to the finishing processes, such as surface milling, that improve the finish quality of the manufactured part. However, there is a lack of knowledge of on how the curvature of the parts affect machining performance. Drilling of non-flat surfaces are not easier to conduct due to slippage and less accuracy. The cutting mechanism on the conventional drilling process is well studied in the conventional metal cutting literature, but on curved non-flat surfaces it is not studied. The thrust force signature in convex curved surface drilling is different from the conventional drilling because of the difference in engagement of chisel edge and cutting lips. It is also observed in the conventional drilling process that cutting parameters such as feed rate and cutting speed have controlling influence on the drilling performance. There is a need to investigate the influence of these cutting parameters on convex curved surfaces as well. Similarly chip clogging and evacuation are very important and decisive factors in the conventional drilling. It would be interesting to visualize and discuss these factors in convex surface drilling. In the case of convex surface drilling, curvature of surface being drilled is also an important factor that can limit the drilling process. The curvature of surface also defines the tool – workpiece engagement and cutting action of chisel edge and cutting lips. Due to convex curved surface, variation in chip load is expected due to variation in the cutting area. Titanium alloy Ti6Al4Vis a commonly used alloy used in the aerospace industry. The aim of this study was to investigate the effects of curvature of a titanium alloy, Ti6Al4V, on the cutting forces experienced during the drilling process. The effects of the curvature of the surface were compared to the effects of the cutting speed and feed rate, in order to establish the significance of the effect of the curvature compared to other factors that affect the drill machining process. The effects of these parameters on the power and temperature during the drilling process were also analyzed and compared. The study is beneficial for the metal cutting academia and industry as it can provide the basic understanding and open up new areas of application.

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Li, Xianchang, and Ting Wang. "Computational Analysis of Surface Curvature Effect on Mist Film Cooling Performance." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27434.

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Air film cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes and blades. Enhancing air film cooling by injecting mist with tiny water droplets with diameters of 5–10μm has been studied in the past on flat surfaces. This paper focuses on computationally investigating the curvature effect on mist/air film cooling enhancement, specifically for film cooling near the leading edge and on the curved surfaces. Numerical simulations are conducted for both 2-D and 3-D settings at low and high operating conditions. The results show, with a nominal blowing ratio of 1.33, air-only adiabatic film cooling effectiveness on the curved surface is less than on a flat surface. The concave (pressure) surface has a better cooling effectiveness than the convex (suction) surface, and the leading edge film cooling has the lowest performance due to main flow impinging against the coolant injection. By adding 2% (weight) mist, film cooling effectiveness can be enhanced approximately 40% at the leading edge, 60% on the concave surface, and 30% on the convex surface. The leading edge film cooling can be significantly affected by changing of the incident angle due to startup or part-load operation. The film cooling coverage could switch from the suction side to the pressure side and leave the surface of the other part unprotected by the cooling film. Under real gas turbine operating conditions at high temperature, pressure, and velocity, mist cooling enhancement could achieve 20% and provides a wall cooling of approximately 180K.

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Berhe, Mulugeta K., and Suhas V. Patankar. "Investigation of Discrete-Hole Film Cooling Parameters Using Curved-Plate Models." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-374.

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Computations have been conducted on curved, three-dimensional discrete-hole film cooling geometries that included the mainflow, injection hole, and supply plenum regions. Both convex and concave film cooling geometries were studied. The effects of several film cooling parameters have been investigated, including the effects of blowing ratio, injection angle, hole length, hole spacing, and hole staggering. The blowing ratio was varied from 0.5 to 1.5, the injection angle from 35° to 65°, the hole length from 1.75D to 6.0D, and the hole spacing from 2D to 3D. The staggered-hole arrangement considered included two rows. The computations were performed by solving the fully elliptic, three dimensional Navier-Stokes equations over a body fitted grid. Turbulence closure was achieved using a modified k-ε model in which algebraic relations were used for the turbulent viscosity and the turbulent Prandtl number. The results presented and discussed include plots of adiabatic effectiveness as well as plots of velocity contours and velocity vectors in cross-stream planes. The present study reveals that the blowing ratio, hole spacing, and hole staggering are among the most significant film cooling parameters. Furthermore: (1) the optimum blowing ratios for curved surfaces are higher than those for flat surfaces, (2) a reduction of hole spacing from 3D to 2D resulted in a very significant increase in adiabatic effectiveness, especially on the concave surface, (3) the increase in cooling effectiveness with decreasing hole spacing was found due to not only the increased coolant mass per unit area, but also the smaller jet penetration and the weaker counter-rotating vortices, (4) for all practical purposes, the hole length was found to be a much less significant film cooling parameter.

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