한국광학회지 (Korean Journal of Optics and Photonics)

  • 제33권6호
  • /
  • Pages.267-274
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  • 2022
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  • 1225-6285(pISSN)
  • /
  • 2287-321X(eISSN)
한국광학회 (Optical Society of Korea)
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균일 밝기 랜덤 도트 어레이 생성을 위한 이진 회절광학소자 설계 및 제작

Design and Fabrication of Binary Diffractive Optical Elements for the Creation of Pseudorandom Dot Arrays of Uniform Brightness

  • 이수연 (공주대학교 광공학과) ;
  • 이준호 (공주대학교 광공학과) ;
  • 김영광 (한국표준과학연구원) ;
  • 이혁교 (한국표준과학연구원) ;
  • 이문섭 (ETRI 호남권 연구센터 광융합시스템연구실)
  • Lee, Soo Yeon (Department of Optical Engineering, Kongju National University) ;
  • Lee, Jun Ho (Department of Optical Engineering, Kongju National University) ;
  • Kim, Young-Gwang (Center for Space Optics, Korea Research Institute of Standards and Science) ;
  • Rhee, Hyug-Gyo (Center for Space Optics, Korea Research Institute of Standards and Science) ;
  • Lee, Munseob (Honam Research Center, Electronics and Telecommunications Research Institute)
  • 투고 : 2022.09.26
  • 심사 : 2022.10.27
  • 발행 : 2022.12.25
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초록

쉴리렌 이미징을 위한 랜덤 도트 배열 투영용 이진 회절광학소자를 설계하고 제작하였다. 이 연구에서 적용된 회절광학소자는 단 두 단계의 위상 및 10 ㎛의 피치를 갖는 이진 위상 회절 격자로, 제작 단가 및 제작 공정의 용이성을 위하여 선택되었다. 회절광학소자의 설계는 최종 패턴의 밝기 정보를 목적 함수로 사용하는 iterative Fourier transform algorithm을 적용하였다. 먼저 균일 밝기의 랜덤 도트 이미지를 생성하였고, 이를 최종 목표 이미지(패턴)로 적용한 결과, 위치(시야)에 따른 랜덤 도트의 밝기 변화를 확인하였다. 이를 해결하기 위하여 최종 목표 패턴에 가우시안 가중치를 적용한 개선 설계를 적용하였고, 그 결과 패턴 밝기 균일도를 52.7%에서 90.8%까지 향상시켰다. 이후, 바이너리 회절 소자 및 이를 적용한 빔 투사기를 제작하여 설계 결과를 검증하였다. 검증 결과 투사 거리 5 m에서 설계 목표인 430 mm × 430 mm 투광면적, 10,000개 이상의 랜덤 도트 패턴의 생성을 확인하였다. 측정된 균일도는 시뮬레이션에서 예상되었던 균일도보다 다소 적은 84.5%이나, 이는 회절 격자 형상, 특히 모서리 뭉개짐 및 간격 오류에 의한 것으로 추정된다.

In this paper, we report the design and fabrication of binary diffractive optical elements (DOEs) for random-dot-pattern projection for Schlieren imaging. We selected the binary phase level and a pitch of 10 ㎛ for the DOE, based on cost effectiveness and ease of manufacture. We designed the binary DOE using an iterative Fourier-transform algorithm with binary phase optimization. During initial optimization, we applied a computer-generated pseudorandom dot pattern of uniform intensity as a target pattern, and found significant intensity nonuniformity across the field. Based on the evaluation of the initial optimization, we weighted the target random dot pattern with Gaussian profiles to improve the intensity uniformity, resulting in the improvement of uniformity from 52.7% to 90.8%. We verified the design performance by fabricating the designed binary DOE and a beam projector, to which the same was applied. The verification confirmed that the projector produced over 10,000 random dot patterns over 430 mm × 430 mm at a distance of 5 meters, as designed, but had a slightly less uniformity of 84.5%. The fabrication errors of the DOE, mainly edge blurring and spacing errors, were strong possibilities for the difference.

키워드

과제정보

이 논문은 미래창조과학부 및 정보통신기술진흥센터의 정보통신·방송 연구개발 사업의 지원을 받아 진행하였음 [No. 1711117093, (세부4) 플렌옵틱 현미경 영상 획득 및 검진 기술 개발].

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