Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Comparison of Phase-Screen-Generation Methods for Simulating the Effects of Atmospheric Turbulence

대기 외란을 모사하는 위상판 생성 방법 비교

  • Ha, Dung T. (School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Mai, Vuong V. (School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Kim, Hoon (School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST))
  • ;
  • ;
  • 김훈 (한국과학기술원 전기및전자공학부)
  • Received : 2019.02.08
  • Accepted : 2019.04.30
  • Published : 2019.06.25
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Abstract

Phase screens are widely used to simulate the effects of atmospheric turbulence on the phase fluctuations of a light beam. We compare three sampled-based phase-screen-generation methods (the fast-Fourier-transform, subharmonic, and covariance-matrix methods), in terms of accuracy and simulation time. We show that the covariance method generates the phase screens most accurately, with simulation time comparable to the other sampled-based methods.

대기를 매개로 사용하는 광학 시스템에서 대기의 난류가 빛의 위상에 미치는 영향을 모사하기 위하여 위상판이 널리 사용된다. 본 논문에서는 위상판을 생성하는 3가지 방법을 정확성과 위상판 생성 시간 측면에서 비교 분석한다. 비교에 사용된 샘플 기반 위상판 생성 방법은 FFT, 저조파, 공분산 행렬 방법이다. 공분산 행렬 방법으로 생성된 위상판의 경우 구조 함수 값이 이론치에 매우 가까웠으며, 위상판 생성 시간도 다른 두 방법보다 크게 오래 걸리지 않았다.

Keywords

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Fig. 1. FFT-based phase screen generation method.

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Fig. 2. Modified von Karman spatial power spectrum and the sampling of this spectrum in the FFT method.

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Fig. 3. Concept diagram of the subharmonic method.

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Fig. 4. Flow diagram of the subharmonic method.

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Fig. 5. Flow diagram of the covariance matrix method.

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Fig. 6. (a) Phase screen generated by using FFT method. (b) Phase screen generated by using subharmonic method. (c) Phase screen generated by using covariance matrix method.

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Fig. 7. (a) Structure function of phase screens generated by using FFT method. (b) Structure function of phase screen at r = 1 m and simulation time as a function of the size of phase screen when the FFT method is used.

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Fig. 8. (a) Structure function of phase screens generated by using subharmonic method. (b) Structure function of phase screen at r = 1 m and simulation time as a function of the size of Nsub when the subharmonic method is used.

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Fig. 9. (a) Structure function of phase screens generated by using covariance matrix method. (b) Structure function of phase screen at r = 1 m and simulation time as a function of the size of Nlow when the covariance matrix method is used.

Table 1. Parameters used for the generation of phase screens

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