• Title/Summary/Keyword: holography

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Incoherent Triangular holography using Mercury Lamp (수은등을 이용한 인코히어런트 삼각 홀로그래피)

  • 김수길
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2000.11a
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    • pp.144-148
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    • 2000
  • We presented a modified triangular interferometer as an incoherent holography, which can eliminate bias and conjugate image problems of the conventional one. Also, to demonstrate the feasibility of incoherent holography, the formation of an incoherent hologram using a mercury lamp and its optical reconstruction were presented.

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Acoustic Scattering Holography and Analysis of Its Errors (산란 음향 홀로그래피의 기본 이론 및 오차 해석)

  • 이상협;김양한
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.292-292
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    • 2004
  • There are many difficulties to get the scattered field generated by obstacle which has arbitrary shape or irregular surface impedance by using analytic solution or numerical methods. In this study, we propose experimental method of acoustic scattering holography that can predict the far-field scattered field based on nearfield measurements. First of all, we express scattered field using K-H integral equation and compare the differences of which green's function we use. Also we consider analytic solution of scattered field by infinite cylinder to analysis for the errors due to apply cylinderical holography. So the errors which caused by holography due to frequency (ka) and microphone spacing are also analyzed by numerical simulation.

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Removal of bias and conjugate image using the modified conoscopic holography (변형된 코노스코픽 홀로그래피를 이용한 바이어스와 공액영상의 제거)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.12
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    • pp.22-27
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    • 2015
  • Conoscopic holography, which consists of two linear polarizers and two wave plates, and an uniaxial crystal, is incoherent holographic technology for three-dimensional display. In the uniaxial crystal, the wave from object divides into extraordinary and ordinary waves and phase difference between two waves is caused by the different refractive index of two waves. Four intensity patterns, which are made by phase difference, are obtained using LCLV(liquid crystal light valve) and conoscopic holography system. By combining four intensity patterns, the complex hologram without bias and conjugate image. In this paper, we propose the optimized system, which consists of a wave plate and a linear polarizer, and uniaxial crystal. In the proposed system, it doesn't need LCLV. By adjusting the azimuth angle of a linear polarizer and a wave plate, we derive four intensity patterns in recording plane. We demonstrate theoretically that the complex hologram with bias and a conjugate image is obtained using the proposed system.

New LEDs improve the quality of illumination of full-color holograms recorded with red 660 nm, green 532 nm and blue 440 nm lasers

  • Gentet, Philippe;Gentet, Yves;Joung, Jinbeom;Park, Sungchul;Park, Misoo;Lee, Seunghyun
    • International Journal of Advanced Culture Technology
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    • v.7 no.4
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    • pp.274-282
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    • 2019
  • This paper discusses the main requirements in today's full-color holograms illumination and evaluates the last generation of LEDs, the actual best light source to render properly the colors of the holograms and in particular those recorded with red 660 nm, green 532 nm and blue 440 nm lasers. This paper presents also the first prototype of lamp designed especially for this kind of holograms.

Micro-Structure Measurement and Imaging Based on Digital Holography

  • Kim, Kyeong-Suk;Jung, Hyun-Chul;Chang, Ho-Seob;Kee, Chang-Doo;Akhter, Naseem
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.3
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    • pp.257-260
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    • 2010
  • Advancements in the imaging and computing technology have opened the path to digital holography for non-destructive investigations of technical samples, material property measurement, vibration analysis, flow visualization and stress analysis in aerospace industry which has widened the application of digital holography in the above fields. In this paper, we demonstrate the non-destructive investigation and micro-structure measurement application of digital holography to the small particles and a biological sample. This paper gives a brief description of the digital holograms recorded with this system and illustratively demonstrated.

Prediction of Sound Field Inside Duct with Moving Medium by using one Dimensional Green's function (평균 유동을 고려한 1차원 그린 함수를 이용한 덕트 내부의 음장 예측 방법)

  • Jeon, Jong-Hoon;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.915-918
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    • 2005
  • Acoustic holography uses Kirchhoff·Helmholtz integral equation and Green's function which satisfies Dirichlet boundary condition Applications of acoustic holography have been taken to the sound field neglecting the effect of flow. The uniform flow, however, changes sound field and the governing equation, Green's function and so on. Thus the conventional method of acoustic holography should be changed. In this research, one possibility to apply acoustic holography to the sound field with uniform flow is introduced through checking for the plane wave in a duct. Change of Green's function due to uniform flow and one method to derive modified form of Kirchhoff·Heimholtz integral is suggested for 1-dimensional sound field. Derivation results show that using Green's function satisfying Dirichlet boundary condition, we can predict sound pressure in a duct using boundary value.

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Research and Standardization Trends of Digital Hologram Compression (디지털 홀로그램 압축 기술 및 표준화 동향)

  • Oh, K.J.;Park, J.
    • Electronics and Telecommunications Trends
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    • v.34 no.6
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    • pp.145-155
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    • 2019
  • Holography is a technique that can acquire and reproduce 3D objects nearly perfectly by representing both the amplitude and phase of light. Recently, digital holography has received considerable attention because it is simpler than analog holography from acquisition to reproduction. The data size of the digital hologram increases tremendously as the quality of digital holograms depends on their pixel pitch and resolution. Hence, efficient compression is necessary to realize holographic imaging services. In this report, we introduce recent digital hologram compression techniques and JPEG Pleno holography, which is the first international standardization activity for digital hologram compression. Furthermore, we discuss the future of this field.

Recording and Reconstruction of large object area by using Reflection type Digital Holography Microscope System (반사형 디지털 홀로그래피 현미경 시스템에서의 조사면적 및 재생면적의 확대기록)

  • Choi, Kyu-Hwan;Kim, Sung-Kyu;Cho, D.;Yoon, Seon-Kyu
    • Korean Journal of Optics and Photonics
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    • v.17 no.4
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    • pp.335-341
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    • 2006
  • A modified Michelson interferometer type digital holography microscopy system is developed. There is a problem about recording and numerical reconstruction area at the microscopy application of Michelson type interferometer structure in the digital holography field. In this paper, to overcome this problem, we developed a new reflection type digital holography microscope system and increased recording and numerical reconstruction area of target object.