Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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A Study on the Method of Evaluating Optical-system Performance and an Athermal Structure through Thermal Analysis of the Korsch Telescope

Korsch 망원경의 열분석을 통한 광학계 성능 평가 방법 및 비열화 구조 연구

  • Kim, Kyu-Ho (Department of Nano & Semiconductor Engineering, Korea Polytechnic University) ;
  • Park, Seong-Woo (Department of Nano & Semiconductor Engineering, Korea Polytechnic University) ;
  • Park, Seung-Han (Department of Optics and Photonics, Yonsei University) ;
  • Lee, Kyoung-Mook (Satellite System 2 Team, Hanwha Systems) ;
  • Jung, Mee-Suk (Department of Nano & Semiconductor Engineering, Korea Polytechnic University)
  • 김규호 (한국산업기술대학교 나노반도체공학과) ;
  • 박성우 (한국산업기술대학교 나노반도체공학과) ;
  • 박승한 (연세대학교 광과학공학과) ;
  • 이경묵 (한화시스템 위성시스템 2팀) ;
  • 정미숙 (한국산업기술대학교 나노반도체공학과)
  • Received : 2021.11.04
  • Accepted : 2021.11.22
  • Published : 2021.12.25
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Abstract

In this paper, a method for evaluating optical-system performance and an athermal structure through thermal analysis of the Korsch telescope was studied. In the case of an optical system having a complex asymmetrical structure, there is a limit to implementing the satellite structure by applying the coefficient of thermal expansion (CTE) in the optical-design software, so it is difficult to evaluate the performance of the optical system against temperature changes. To solve this problem, using mechanical design software all length changes were implemented in all structures that affect the optical system according to temperature, and the value of the change in distance between optical components due to temperature change was organized. Also, the values of changes in shape and thickness of the optical components against temperature changes are organized in the optical-design software. All changes derived from both software packages were applied in the optical software to evaluate the performance of the optical system. As a result, it was found that the MTF for a spatial resolution of 71.4 cycles/mm was maintained at more than 25% in the range from 9 ℃ to 33 ℃. In addition, the performance of the optical system applying the improved structure was evaluated, by finding the structure that had the most influence on the optical system's performance change, and deriving an athermal structure to reduce the effect. As a result, it was found that the MTF for a resolution of 71.4 cycles/mm was maintained at over 67% in the range from 9 ℃ to 33 ℃.

본 논문은 Korsch 망원경의 열분석을 통한 광학계 성능 평가 방법 및 비열화 구조를 연구하였다. 비대칭성의 복잡한 구조를 가진 광학계의 경우, 광학 설계 소프트웨어에 열팽창 계수를 적용하여 인공위성 구조를 구현하는데 한계가 있어 온도 변화에 대한 광학계 성능 평가가 이루어지기 어렵다. 이러한 문제점을 해결하기 위해 기계 설계 소프트웨어를 이용하여 온도에 따라 광학계에 영향을 주는 모든 구조체에 길이 변화를 구현하였고, 온도 변화에 대한 광학 부품 사이의 거리 변화량을 정리하였다. 또한 광학 설계 소프트웨어를 이용하여 온도 변화에 대한 광학 부품의 형상 및 두께 변화량을 정리하였다. 두 소프트웨어에서 도출한 모든 변화량을 광학 소프트웨어에 적용하여 광학계의 성능 평가를 진행하였다. 그 결과 공간 분해능 71.4 cycles/mm에 대한 변조전달함수(MTF)가 9 ℃에서 33 ℃까지의 범위에서 25% 이상 유지되는 것을 확인하였다. 또한 광학계 성능 변화에 가장 영향을 많이 주는 구조체를 찾아, 영향을 줄이도록 비열화 구조를 도출하여 개선된 구조물을 적용한 광학계의 성능 평가를 진행하였다. 그 결과, 분해능 71.4 cycles/mm에 대한 변조전달함수가 9 ℃에서 33 ℃까지의 범위에서 67% 이상 유지되는 것을 확인하였다.

Keywords

Acknowledgement

본 논문은 2020년도 한화시스템(주)의 재원을 지원받아 수행된 연구임(초소형위성 광학 탑재체 연구).

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