Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Defect Inspection and Physical-parameter Measurement for Silicon Carbide Large-aperture Optical Satellite Telescope Mirrors Made by the Liquid-silicon Infiltration Method

액상 실리콘 침투법으로 제작된 대구경 위성 망원경용 SiC 반사경의 결함 검사와 물성 계수 측정

  • Bae, Jong In (Department of Nanoscience and Technology, Jeonbuk National University) ;
  • Kim, Jeong Won (Material Development Department, Orange E&C Inc.) ;
  • Lee, Haeng Bok (Electro-Optics Department, Agency for Defense Development) ;
  • Kim, Myung-Whun (Department of Nanoscience and Technology, Jeonbuk National University)
  • 배종인 (전북대학교 나노과학기술학과) ;
  • 김정원 (오렌지이엔씨 재료부문) ;
  • 이행복 (국방과학연구소 전자광학팀) ;
  • 김명훈 (전북대학교 나노과학기술학과)
  • Received : 2022.08.16
  • Accepted : 2022.09.27
  • Published : 2022.10.25
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Abstract

We have investigated reliable inspection methods for finding the defects generated during the manufacturing process of lightweight, large-aperture satellite telescope mirrors using silicon carbide, and we have measured the basic physical properties of the mirrors. We applied the advanced ceramic material (ACM) method, a combined method using liquid-silicon penetration sintering and chemical vapor deposition for the carbon molded body, to manufacture four SiC mirrors of different sizes and shapes. We have provided the defect standards for the reflectors systematically by classifying the defects according to the size and shape of the mirrors, and have suggested effective nondestructive methods for mirror surface inspection and internal defect detection. In addition, we have analyzed the measurements of 14 physical parameters (including density, modulus of elasticity, specific heat, and heat-transfer coefficient) that are required to design the mirrors and to predict the mechanical and thermal stability of the final products. In particular, we have studied the detailed measurement methods and results for the elastic modulus, thermal expansion coefficient, and flexural strength to improve the reliability of mechanical property tests.

실리콘 카바이드(SiC) 소재를 이용해서 위성용 대구경 망원경의 경량 반사경을 제작하는 과정에서 발생할 수 있는 결함과 SiC 소재의 기계 및 열적 특성을 조사했다. SiC 반사경 제작에는 advanced ceramic material (ACM) 공법이라고 불리는 탄소성형체를 이용한 액상 실리콘 침투 소결법 및 화학기상 증착법이 사용되었으며, 크기와 형상이 다른 네 가지 SiC 반사경을 개발했다. 반사경의 크기 및 형상에 따라 구분하여 광학 소재의 결함을 검사하는 기준과 방법을 체계적으로 제시했고, 경면 표면검사 및 소재 내부 결함 탐지를 위한 비파괴 검사법과 결과에 대해 분석했다. 또한, 반사경을 설계하고, 최종 완성품의 기계적 열적 안정성을 계산하고 예측하기 위해 필요한 밀도, 탄성계수, 비열, 열전달 계수 등을 포함한 14종의 물성 계수 측정값을 공인시험을 통해 추출했으며, 특히 측정 신뢰도 향상을 위해 주요 물성인 탄성계수, 열팽창 계수, 굽힘 강도 측정 방법과 결과에 대해 자세히 연구했다.

Keywords

Acknowledgement

시료 제작 단계별 검사규격의 해외 사례 및 각종 반사경 제작 기획서 등 다양한 자료 수집에 도움을 준 국방과학연구소, 한국천문연구원, 한국표준과학연구원, 전남테크노파크, 한국전광, 한화시스템 담당자분들과 미국국립천문대 조명규 박사님에게 감사드립니다.

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