• 제목/요약/키워드: axicon lens

검색결과 3건 처리시간 0.015초

Study on terahertz (THz) photoconversion technology based on hyperfine energy-level splitting of Positronium (Ps) generated from relativistic electron beams

  • Sun-Hong Min;Chawon Park;Ilsung Cho;Minho Kim;Sukhwal Ma;Won Taek Hwang;Kyeong Min Kim;Seungwoo Park;Min Young Lee;Eun Ju Kim;Kyo Chul Lee;Yong Jin Lee;Bong Hwan Hong
    • 대한방사성의약품학회지
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    • 제6권2호
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    • pp.102-115
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    • 2020
  • In the state of Positronium (Ps), which is an unstable material created by the temporary combination of electrons and positrons, the imaging technology through photo-conversion methodology is emerging as a new research theme under resonance conditions through terahertz electromagnetic waves. Normally, Positronium can be observed in the positron emission computed tomography (PET) process when an unstable, separate state that remains after the pair annihilation of an electron and a positron remains. In this study, terahertz (THz) waves and Cherenkov radiation (CR) are generated using the principle of ponderomotive force in the plasma wake-field acceleration, and electrons and positrons are simultaneously generated by using a relativistic electron beam without using a PET device. We confirm the possibility of Positronium photoconversion technology in terahertz electromagnetic resonance conditions through experimental studies that generate an unstable state. Here, a relativistic electron beam (REB) energy of 0.5 MeV (γ=2) was used, and the terahertz wave frequencies is G-band. Meanwhile, a THz wave mode converting three-stepped axicon lens was used to apply the photoconversion technology. Through this, light emission in the form of a luminescence-converted Bessel beam can be verified. In the future, it can be used complementarily with PET in nuclear medicine in the field of medical imaging.

신개념 백라이트유닛 모델링 (Modeling for New Type Backlight Units)

  • 이광훈;지승현;김수현;윤영수;김수호
    • 한국광학회지
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    • 제21권2호
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    • pp.41-45
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    • 2010
  • 백라이트유닛을 더 얇고 밝게 제안하기 위하여 우리는 새로운 타입의 백라이트유닛을 시뮬레이션하였다. 도광판 상면에 미세 볼록렌즈어레이를 형성시킨다. 또한, LGP와의 매칭을 위하여 우리는 기능성 광학 시트를 시뮬레이션하였다. 일반적으로 전통적인 백라이트유닛들은 하나의 LGP와 네 개의 광학시트를 사용해왔으나 우리는 하나의 광학시트를 사용한 백라이트유닛을 시뮬레이션하였다. 설계 결과 우리의 백라이트유닛은 동일한 발광성을 달성하면서 시야각은 30% 더 좋아진 것을 밝혀내었다.