Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Prediction Method for Moisture-release Surface Deformation of a Large Mirror in the Space Environment

우주환경에서 대형 반사경의 습기 방출에 의한 형상 변화 예측방법

  • Song, In-Ung (Space Optics Laboratory (SOL), Department of Astronomy, Yonsei University) ;
  • Yang, Ho-Soon (Space Optics Team, Korea Research Institute of Standards and Science) ;
  • Khim, Hagyong (Space Optics Team, Korea Research Institute of Standards and Science) ;
  • Kim, Seong-Hui (Satellite Payload Development Division, Korea Aerospace Research Institute) ;
  • Lee, Hoi-Yoon (Space Optics Team, Korea Research Institute of Standards and Science) ;
  • Kim, Sug-Whan (Space Optics Laboratory (SOL), Department of Astronomy, Yonsei University)
  • 송인웅 (연세대학교 천문우주학과, 우주광학연구실) ;
  • 양호순 (한국표준과학연구원 첨단측정장비연구소 우주광학팀) ;
  • 김학용 (한국표준과학연구원 첨단측정장비연구소 우주광학팀) ;
  • 김성희 (한국항공우주연구원 위성연구본부) ;
  • 이회윤 (한국표준과학연구원 첨단측정장비연구소 우주광학팀) ;
  • 김석환 (연세대학교 천문우주학과, 우주광학연구실)
  • Received : 2018.05.31
  • Accepted : 2018.07.09
  • Published : 2018.08.25
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Abstract

In this paper, we propose a new method to predict a mirror's surface deformation due to the stress of moisture release by a coating in the environment of outer space. We measured the surface deformation of circular samples 50 mm in diameter and 1.03 mm thick, using an interferometer. The results were analyzed using Zernike fringe polynomials. The coating stress caused by moisture release was calculated to be 152.7 MPa. This value was applied to an analytic model of a 1.25 mm thickness sample mirror, confirming that the change of surface deformation could be predicted within the standard deviation of the measurement result ($78.9{\pm}5.9nm$). Using this methodology, we predicted the surface deformation of 600 mm hyperbolic mirror for the Compact Advanced Satellite, which will be launched in 2019. The result is only $2.005{\mu}m$ of focal shift, leading to 2.3% degradation of modulation transfer function (MTF) at the Nyquist frequency, which satisfies the requirement.

본 논문에서는 우주의 진공환경에서 반사경 코팅이 흡수한 습기를 방출하면서 나타나는 경면 형상의 변화를 예측하기 위한 새로운 방법론을 제안한다. 직경 50 mm, 두께 1.03 mm의 원형 시편과 간섭계를 통해 진공환경에서 나타나는 시편 형상 변화량을 측정하고 제르니케 프린지 다항식(Zernike fringe polynomial) 곡률항으로 나타내었다. 그 결과 습기 방출에 따른 코팅 스트레스는 152.7 Mpa로 계산되었다. 계산된 스트레스는 1.25 mm 두께 시편의 수치모사 모델에 적용하여 변화된 형상의 곡률항을 측정결과의 표준편차 이내($78.9{\pm}5.9nm$)로 예측할 수 있음을 검증하였다. 이 방법론을 2019년에 발사 예정인 차세대중형위성의 직경 600 mm 쌍곡면경에 적용, 습기 방출에 의한 경면 형상 변화를 계산하여 반사경의 초점거리가 약 $2.005{\mu}m$ 만큼 ?아짐을 예측하였다. 초점거리 변화는 광학 탑재체의 MTF를 한계공간주파수(Nyquist frequency)에서 2.3% 가량 낮추지만, 요구 사양을 만족하여 우주에서도 문제없이 운용 가능함을 확인하였다.

Keywords

References

  1. M. A. Norris and E. G. Wolff, "Moisture expansion measurement and data analysis techniques for composite structures," in Proc. 40th International SAMPE Symposium (USA, May 1995), pp. 1867-1879.
  2. H. K. Pulker and E. Jung, "Correlation between film structure and sorption behaviour of vapour deposited ZnS, cryolite and MgF2 films," Thin Solid Films 9, 57-66 (1972). https://doi.org/10.1016/0040-6090(72)90330-6
  3. H. A. Macleod, "Structure-related optical properties of thin films," J. Vac. Sci. Technol. A 4, 418-422 (1986).
  4. H. K. Pulker and J. Maser, "The origin of mechanical stress in vacuum-deposited $MgF_2$ and ZnS films," Thin Solid Films 59, 65-76 (1979). https://doi.org/10.1016/0040-6090(79)90365-1
  5. K. Kinosita and N. Mineo, "Porosity of $MgF_2$ films - evaluation based on changes in refractive index due to adsorption of vapors," J. Vac. Sci. Technol. 6, 730-733 (1969). https://doi.org/10.1116/1.1315743
  6. S. Ogura, N. Sugawara, and R. Hiraga, "Refractive index and packing density for $MgF_2$ films: correlation of temperature dependence with water sorption," Thin Solid Films 30, 3-10 (1975). https://doi.org/10.1016/0040-6090(75)90298-9
  7. H. K. Pulker, "Stress, adherence, hardness, and density of optical thin films," Proc. SPIE 0325 (1982).
  8. H. A. Macleod, "Microstructure of optical thin films," Proc. SPIE 0325 (1982).
  9. G. N. Strauss, Mechanical Stress in Optical Coatings (Optical Interference Coatings, Springer Berlin Heidelberg, 2003), pp. 207-229.
  10. C. J. Stolz, J. R. Taylor, W. K. Eickelberg, and J. D. Lindh, "Effects of vacuum exposure on stress and spectral shift of high reflective coatings," Appl. Opt. 32, 5666-5672 (1993). https://doi.org/10.1364/AO.32.005666
  11. P.-Y. Bely, The Design and Construction of Large Optical Telescopes (Springer Science & Business Media, 2003).
  12. W. J. Larson J. R. Wertz, Space Mission Analysis and Design (No. DOE/NE/32145--T1. Microcosm, Inc., Torrance, USA, 1992).
  13. A. Poenninger and B. Defoort, "Determination of the coefficient of moisture expansion (CME)," in Proc. 9th International Symposium on Materials in a Space Environment (The Netherlands, Jun. 2003), pp. 567-572.
  14. E. Estrada, F. Colozzi, and H. Jabs, "A new highly accurate CME test facility," in Proc. Spacecraft Structures, Materials & Mechanical Testing, International Conference (The Netherlands, 1996), pp. 585-590.
  15. W. Riede, P. Allenspacher, L. Jensen, and M. Jupe, "Analysis of the air-vacuum effect in dielectric coatings," Proc. SPIE 7132, 71320F (2008).
  16. D. Wernham, "Optical coatings in space," Proc. SPIE 8168, 81680F (2011).
  17. G. G. Stoney, "The tension of metallic films deposited by electrolysis," Proc. R. Soc. Lond. A 82, 172-175 (1909). https://doi.org/10.1098/rspa.1909.0021
  18. N. Schwarzer and F. Richter, "On the determination of film stress from substrate bending: STONEY's formula and its limits," (2006).
  19. von F. Zernike, "Beugungstheorie des schneidenver-fahrens und seiner verbesserten form, der phasenkontrastmethode," Phys. 1, 689-704 (1934).
  20. D. Malacara, Optical Shop Testing (John Wiley & Sons, 2007), Vol. 59.
  21. ARDEC, US Army, "MIL-PRF-13830B American military standards," United States Department of Defense (1992).
  22. Dassault Systemes, "Emes 2005-2007 Catia V5 Manuals," (2005).
  23. K. B. Doyle, V. L. Genberg, and G. J. Michels, Integrated Optomechanical Analysis (SPIE Press, 2002), Vol. 58.
  24. N. Schwarzer, "About the theory of thin coated plates," (2002).
  25. H. Kihm, H.-S. Yang, and Y.-W. Lee, "Optomechanical analysis of a 1-m light-weight mirror system," J. Korean Phys. Soc. 62, 1239-1246 (2013). https://doi.org/10.3938/jkps.62.1239
  26. CODE, V, "Reference Manuals (Version 10.6)," Synopsys OSG (2014).
  27. D. Korsch, "Closed form solution for three-mirror telescopes, corrected for spherical aberration, coma, astigmatism, and field curvature," Appl. Opt. 11, 2986-2987 (1972). https://doi.org/10.1364/AO.11.002986