• 제목/요약/키워드: optics

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E-polarized electromagnetic diffraction by a composite wedge, I: physical optics solution (도체와 유전체가 복합된 쇄기에 의한 E-편파된 전자파의 회절, I: 물리광학해)

  • 김세윤;김상욱
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.8
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    • pp.39-46
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    • 1995
  • A complete form of physical optics solution to the E-polarized diffraction by a composite of conducting and dielectric wedges is obtained by sum ov geometrical optics solution and edge-diffracted field. The diffraction coefficients of the edge-diffracted field are expressed in series of cotangent functions. The electric field patterns of the physical optics solution are plotted in figures.

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Quantifying Aberrations on Object Plane Using Zernike Polynomials

  • Yohan Kim;Theo Nam Sohn;Cheong Soo Seo;Jin Young Sohn
    • Current Optics and Photonics
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    • v.8 no.2
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    • pp.151-155
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    • 2024
  • Optical systems often suffer from optical aberrations caused by imperfect hardware, which places significant constraints on their utility and performance. To reduce these undesirable effects, a comprehensive understanding of the aberrations inherent to optical systems is needed. This article presents an effective method for aberration detection using Zernike polynomials. The process involves scanning the object plane to identify the optimal focus and subsequently fitting the acquired focus data to Zernike polynomials. This fitting procedure facilitates the analysis of various aberrations in the optical system.

Survey of the Brand and Design Recognition Between Domestic Goods and Foreign Ones in the Eye Glasses Industry (국내·외 안경제품들의 디자인 및 브랜드 인지도와 선호도에 관한 조사)

  • Cho, Hyun-Gug;Moon, Byeong-Yeon;Kwak, Ho-Weon;Son, Jeong-Sik;Kim, Ki-Hong;Yu, Dong-Sik
    • Journal of Korean Ophthalmic Optics Society
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    • v.11 no.3
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    • pp.207-215
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    • 2006
  • This study surveys the brand and design recognition by an expert vs. non-expert group in the eye glasses industry. This survey is to search for a way for domestic brands to compete and win foreign ones. The non-expert group chose design as the most noteworthy difference between domestic and foreign brands; likewise, the expert group appeared to first consider design on their choice. Brand recognition by the non-expert group appeared very low; on the other hand, expert group's recognition was higher with domestic brands than with foreign ones. In conclusion, the bounce back of domestic eye glasses business does not seem to be possible in a snap by a special recipe; rather, it is necessary to invest and make efforts to develop new techniques for better quality on the one hand, and to increase brand and design recognition on the other.

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Temperature Dependent Terahertz Generation at Periodically Poled Stoichiometric Lithium Tantalate Crystal Using Femtosecond Laser Pulses

  • Yu, N.E.;Kang, C.;Yoo, H.K.;Jung, C.;Lee, Y.L.;Kee, C.S.;Ko, D.K.;Lee, J.
    • Journal of the Optical Society of Korea
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    • v.12 no.3
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    • pp.200-204
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    • 2008
  • Coherent tunable terahertz generation was demonstrated in periodically poled stoichiometric lithium tantalate crystal via difference frequency generation of femtosecond laser pulses. Simultaneous forward and backward terahertz radiations were obtained around 1.35 and 0.63 THz, respectively at low temperature. By cooling the crystal to reduce losses caused by phonon absorptions, the generated THz bandwidth was as narrow as 23GHz at the center frequency of 0.63 THz. The measurement result of temperature-dependent showed gradual intensity increase of the generated terahertz pulse and red shift of the center frequency as the temperature decrease from 291 to 143 K, but insignificant reduction of the spectral bandwidth. Furthermore, the stoichiometric crystal was very suitable for the suppression of THz loss at low temperature compared to the congruent $LiNbO_3$ crystal.

Fabrication Measurement and Evaluation of a Parabolic Mirror with the Diameter of 450 mm(f/2.7) by Autostigmatic Null Lens System (자동무수차점 방식 널 렌즈 광학계를 이용한 직경 450 mm(f/2.7) 포물면경의 제작 및 측정 평가)

  • Lee, Young-Hun;Jo, Jae-Heung;Rim, Cheon-Seog;Lee, Yun-Woo;Yang, Ho-Soon;Lee, Jae-Hyeob;Lee, In-Won
    • Korean Journal of Optics and Photonics
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    • v.17 no.2
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    • pp.165-174
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    • 2006
  • The autotstigmatic null lens system is designed and constructed for the fabrication of a parabolic mirror with the diameter of 450 mm(f/2.7). And the measurement reliability is also analyzed theoretically by means of the tolerancing technique using lens design software(CODE V). From this analysis, we can precisely fabricate a parabolic mirror with the large diameter of 450 mm(f/2.7). Meanwhile, in order to confirm the fabrication results by the autostigmatic method, the mirror surface is tested again by an autocollimating method that uses only a plane mirror without any null lens.