Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Measurement of Primary-mirror Vertex Coordinates for a Space Camera by Using a Computer-generated Hologram and a Theodolite

컴퓨터 제작 홀로그램과 데오도라이트를 이용한 인공위성 카메라 주 반사경의 정점 좌표 측정

  • Kang, Hye-Eun (Science of Measurement, University of Science and Technology) ;
  • Song, Jae-Bong (Center for Space Optics, Korea Research Institute of Standards and Science) ;
  • Yang, Ho-soon (Science of Measurement, University of Science and Technology) ;
  • Kihm, Hagyong (Science of Measurement, University of Science and Technology)
  • 강혜은 (과학기술연합대학원대학교 측정과학과) ;
  • 송재봉 (한국표준과학연구원 우주광학센터) ;
  • 양호순 (과학기술연합대학원대학교 측정과학과) ;
  • 김학용 (과학기술연합대학원대학교 측정과학과)
  • Received : 2017.04.30
  • Accepted : 2017.06.22
  • Published : 2017.08.25
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Abstract

Alignment of the mirrors composing a space telescope is an important process for obtaining high optical resolution and performance of the camera system. The alignment of mirrors using cube mirrors requires a relative coordinate mapping between the mirror and the cube mirror before optical-system integration. Therefore, to align the spacecraft camera mirrors, the relative coordinates of the vertex of each mirror and the corresponding cube mirror must be accurately measured. This paper proposes a new method for finding the vertex position of a primary mirror, by using an optical fiber and alignment segments of a computer-generated hologram (CGH). The measurement system is composed of an optical testing interferometer and a multimode optical fiber. We used two theodolites to measure the relative coordinates of the optical fiber located at the mirror vertex with respect to the cube mirror, and achieved a measurement precision of better than $25{\mu}m$.

우주용 인공위성 카메라를 구성하는 반사경의 정렬은 광학계의 고분해능, 고성능을 얻기 위한 중요한 과정 중 하나이다. 반사경들의 상호정렬에는 큐브미러(cube mirror)가 대신 사용되기 때문에, 각 반사경과 해당 큐브미러 간의 상호위치관계 정보가 우선 필요하다. 따라서 우주용 카메라 반사경들의 정렬을 위해 각 반사경의 정점과 해당 큐브미러의 상대 좌표값을 정확하게 측정해야하며, 본 논문에서는 컴퓨터 제작 홀로그램(computer-generated hologram, CGH)의 정렬용 세그먼트와 광섬유를 이용하는 새로운 측정 시스템을 제안함으로써 우주용 카메라를 구성하는 반사경의 정점을 요구조건 이내로 측정할 수 있었다. 측정 시스템은 광학계 평가용 간섭계, CGH, 광섬유, 반사경으로 구성되어 있으며, 최종적으로 데오도라이트를 이용해 큐브미러를 기준으로 주 반사경의 정점에 위치한 광섬유 끝단의 3차원 상대 좌표값을 $25{\mu}m$ 이하의 정밀도로 측정할 수 있었다.

Keywords

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