• Title/Summary/Keyword: Diffraction and scattering

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GTD Analysis of Electromagnetic Plane Wave Scattering by Open-Ended Parallel Plate Waveguide with a Slanted Terminator Inside (GTD를 이용한 경사진 벽으로 막힌 평행도파관의 전자파 산란 해석)

  • 선영식;명노훈
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.11
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    • pp.19-24
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    • 1992
  • In this paper, a high frequency method is developed which combines the uniform Geometrical Theory of Diffraction(GTD) and the Aperture Integration(AI) to analyze electromagnetic plane wave scattering by a perfectly-conducting, open-ended, semi-infinite parallel plate waveguide with a uniform layer of absorbing material on its inner wall, and with a slanted planar termination inside. In this method, first, the field of an arbitary point inside the paraller plate waveguide is computed by the GTD. Second, the field scattered into exterior region by the waveguide is found using the equivalent current, which can be obtaind from the aperture field of the waveguide and using the AI. Numerical results based on this GTD method are presented and compared with those based on the mode matching method.

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Phase Stability of Laser-ablated $SmBa_2Cu_3O_{7-y}$ thin Films Investigated by Raman Scattering Spectroscopy

  • Kim, G.;Jeong, A.R.;Jo, W.;Park, D.Y.;Cheong, H.;Tsukada, A.;Hammond, R.H.;Beasley, M.R.
    • Progress in Superconductivity
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    • v.11 no.2
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    • pp.141-146
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    • 2010
  • Phase stability diagram and boundary of a- and c-axis orientation of $SmBa_2Cu_3O_{7-y}$ (SmBCO) thin films grown by pulsed laser deposition (PLD) were reported with studies based on x-ray diffraction [1]. Four different samples are systematically analyzed: normal c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$, a-axis oriented $SmBa_2Cu_3O_{7-y}$, c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ with $Sm_2BaCuO_5$ phase, and a mixture with c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ and anomalously long-c tetragonal $SmBa_2Cu_3O_x$. Raman scattering spectroscopy equipped with polarization analysis elucidates the crystal orientation and the origin of the growth of the materials. It indicates that the technique can be used for quality control of conductor manufacturing processes as well as for enhancement of the materials properties.

Diffraction of gaussian beam wave by finite periodic conducting strip grating on a grounded dielectric slab (접지된 유전체층위에 주기적인 스트립구조로서 구성되어 있는 유한한 격자구조에 의한 가우시안 빔의 회절특성)

  • 이종익;조영기
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.10
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    • pp.45-52
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    • 1997
  • An analysis method for the electromagnetic scattering of a gaussian beam wave by finite periodic conducting strip grating on a groudned dielectric slab is considered. The intergral equation for the unknown current induced on the conducting strip surface is derived and solbed numerically by use of the method of moment. From knowledge of the strip current, the quantities of interest such as radiation pattern, the space wave power radiated into the free space, and the coupled surface wave power propagating along the dielectric slab are computed for the appropriately chosen parametes Some similarity between scattering behaviours of the present geometry and the infinite geometry is examined by observing the Off-bragg as well as bragg blaxing penomena in both geometries.The validity of the numerical results are assured by a check of the power conservation relations.

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Synthesis of Diamond films for Radiation Detector (방사선 검출기용 다이아몬드 막의 합성)

  • 박상현;김정달;박재윤;김경환;구효근;이덕출
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.366-369
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    • 1999
  • Synthetic diamond films have been deposited on the silicon(100) surface and molybdenum substrates using an microwave plasma enhanced vapor deposition (MWPECVD) method. The effect of deposition time, surface morphology, X-ray diffraction pattrm, infrared transmittance and Raman Scattering have been studied, The diamond film deposited on Mo substrate for (100) hours at 40 torr H$_2$-CH$_4$O$_2$ gas system have been shown 1${\mu}{\textrm}{m}$/h of growth rate and good crystallization

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Analysis of Resonance Scattering Characteristics by Multi-layered Dielectric Gratings (다층 유전체 격자구조에 의한 공진 산란특성의 분석)

  • Ho, Kwang-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.1
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    • pp.231-236
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    • 2017
  • The space harmonics generated by a plane-wave incident upon a multi-layered dielectric grating can undergo strong resonance scattering variations known as GMR(guided-mode resonance). To clarify these effects, we examine the field propagation and dispersion curve inside the grating region by using a rigorous equivalent transmission-line theory(RETT). The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, we confirm and generalize previous research that has occurred GMR effect associated with the free-resonant character of leaky waves at multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TM mode.

A novel method for the synthesis of nano-magnetite particles

  • Syahmazgi, Maryam Ghodrati;Falamaki, Cavus;Lotfi, Abbas Sahebghadam
    • Advances in nano research
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    • v.2 no.2
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    • pp.89-98
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    • 2014
  • A novel and simple method for the synthesis of nano-magnetite particles is disclosed. In the novel procedure, $Fe^{2+}$ is the only source of metal cation. Carboxymethylcellulose (CMC) is used as the structure directing agent. The phase analysis of the nano-particles was performed using XRD and electron diffraction techniques. Size and morphology analysis was performed using light scattering and TEM techniques. The effect of $NH_4OH$ solution (32 wt. %) at different CMC concentrations on the size distribution of the final magnetite powders is studied. An optimal base concentration exists for each CMC concentration leading to minimal agglomeration. There exists a minimum CMC concentration (0.0016 wt. %), lower than that no magnetite forms. It is shown that using the new method, it is possible to immobilize a lipase enzyme (Candida Rugosa) with immobilization efficiency larger than 98 % with a loading more than 3 times the reported value in the literature. The latter phenomenon is explained based on the agglomerate state of the nano-particles in the liquid phase.

The Optical Design of Miniaturized Microscope Objective for CARS Imaging Catheter with Fiber Bundle

  • Rim, Cheon-Seog
    • Journal of the Optical Society of Korea
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    • v.14 no.4
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    • pp.424-430
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    • 2010
  • In coherent anti-Stokes Raman scattering (CARS) microscopy reported until now, conventional microscope objectives are used, so that they are limited for introduction into a living body. Gradient-index (GRIN) rod lenses might be a solution for miniaturized microscope objectives for in-vivo CARS microscopy. However, due to the inherent large amount of chromatic aberration, GRIN rod lenses cannot be utilized for this purpose. CARS imaging catheter, composed of miniaturized microscope objective and fiber bundle, can be introduced into a living body for minimally invasive diagnosis. In order to design the catheter, we have to first investigate design requirements. And then, the optical design is processed with design strategies and intensive computing power to achieve the design requirements. We report the miniaturized objective lens system with diffraction-limited performance and completely corrected chromatic aberrations for an in-vivo CARS imaging catheter.

The Analysis of Scattering Characteristics of a Prime-focus Offset Parabolic Antenna with a Shaped Edge Structure (정형 모서리 구조를 갖는 옵\ulcornerV 파라볼릭 안테나의 산란 특성 해석)

  • 박대성;김형규;최재훈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.3
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    • pp.412-418
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    • 1999
  • The scattering characteristics of a prime-focus offset-parabolic antenna are analyzed using UTD. First, ray tracing method is used to locate the shadow boundaries, and then UTD is utilized to evalute the far-zone scattered magnetic field pattern. The field components included in the UTD analysis are the reflected, edge diffracted and creeping waves. The effects of circular caps attached to both edges of a prime-focus offset-parabolic antenna are investigated by comparing the scattered magnetic field patterns with those of a knife edge parabolic reflector.

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Introduction to Neutron Scattering for Magnetic Materials Research (자성소재 연구를 위한 중성자산란 입문)

  • Jeong, Jae-Hong;Lee, Sang-Hyun;Park, Je-Geun
    • Journal of the Korean Magnetics Society
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    • v.22 no.3
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    • pp.103-108
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    • 2012
  • Having a de Broglie wavelength of a few ${\AA}$ with its corresponding energies in the range of a few to a few hundreds meV, neutrons are ideally suited for the studies of structure and dynamics in condensed matter research. Neutron scattering has been developed over the past 60 years or so and become a very mature and established experimental technique in the very broad range of material sciences. In this short introductory article, we have explained its working principles and provided few selected examples of application.

Green Synthesis of Ag Thin Films on Glass Substrates and Their Application in Surface-Enhanced Raman Scattering

  • Cho, Young Kwan;Kim, In Hyun;Shin, Kuan Soo
    • Bulletin of the Korean Chemical Society
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    • v.34 no.10
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    • pp.2942-2946
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    • 2013
  • Nanostructured Ag thin films could be facilely prepared by soaking glass substrates in ethanolic solutions containing $Ag_2O$ powders at an elevated temperature. The formation of zero-valent Ag was corroborated using X-ray diffraction and X-ray photoelectron spectroscopy. The deposition of Ag onto a glass substrate was readily controlled simply by changing the reaction time. Due to the aggregated structures of Ag, the surface-enhanced Raman scattering spectra of benzenethiol could be clearly identified using the Ag-coated glass. The enhancement factor at 514.5 nm excitation estimated using benzenethiol reached $1.0{\times}10^5$ while the detection limit of rhodamine 6G was found to be as low as $1.0{\times}10^{-13}$ M. Since this one-pot fabrication method is eco-friendly and is suitable for the mass production of diverse Ag films, it is expected to play a significant role in the development of surface plasmon-based analytical devices.