Infrared and Laser Engineering, Volume. 53, Issue 1, 20230412(2024)

Experiment study on large solar telescope mirror seeing

Yan Wang1,2, Yongxing Yang3, Jinpeng Li1,2,3, Yong Bi1,2,3, and Qingsheng Zhu1,2,3
Author Affiliations
  • 1Nanjing Research Center of Astronomical Instruments, Chinese Academy of Sciences, Nanjing 210042, China
  • 2University of Science and Technology of China, Hefei 230022, China
  • 3Nanjing Astronomical Instruments Co., Ltd., Chinese Academy of Sciences, Nanjing 210042, China
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    Figures & Tables(15)
    The laminar state and turbulent state diagram
    Relationship between FWHM and Strehl Intensity
    Optical schematic of the mirror seeing experiment
    Photo of the mirror seeing experiment
    System overall layout (The hollow circles are SMD temperature sensors and air temperature sensors; the hollow cylinder is the ultrasonic wind direction and speed sensor; the red rectangle is the silicone rubber heating plate; the trapezoid is the electric fan)
    Temperature sensors curve with time for free convection
    Test result diagram of ɸ1.55 m large hyperboloid reflector primary mirror
    Strehl Intensity as a function of mirror-air temperature difference for the 1550 mm mirror (The filled portion of the figure shows the error statistics for multiple sets of experimental data)
    FWHM as a function of mirror-air temperature difference for the 1550 mm mirror (The filled portion of the figure shows the error statistics for multiple sets of experimental data)
    Seeing as a function of mirror-air temperature difference for free convection
    FWHM/\begin{document}$ \Delta {T}_{m} $\end{document} as a function of the Froude number for forced convection
    • Table 1. Equipment parameter list

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      Table 1. Equipment parameter list

      SpeciesParameter
      4D interferometerDiameter: 9 mm; Focal length: 14 mmWorking band: 632.8 nm
      Compensating mirror setDiameter: 82 mm; Material: H-K9LFlat 1 curvature radius: −154.88 mmFlat 2 curvature radius: −325.9 mmDistance between mirrors: −27.506 mm
      Large hyperboloid reflector primary mirrorDiameter: 1550 mm; Off-axis distance: 1500 mmMaterial: glass-ceramic; Coating:enhanced aluminum
      Flat mirrorDiameter: 1800 mm; RMS: λ/40 (632.8 nm)Material: glass-ceramic
    • Table 2. Summary of test results for free convection (Mirror velocity=0 m/s)

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      Table 2. Summary of test results for free convection (Mirror velocity=0 m/s)

      ModelMirror velocity/m·s−1$ {\Delta T}_{m} $/℃$ {r}_{0} $/cmStrehl ratioFWHM/(″)
      Free convectionU=0020.670.980.03
      0.212.400.970.05
      0.54.770.880.13
      0.81.940.710.32
      11.480.620.42
      1.51.130.510.55
      20.890.400.70
      2.50.740.310.84
      30.640.220.97
      3.50.550.171.18
      40.430.151.43
    • Table 3. Summary of test results for forced convection at low wind speed (Mirror velocity=0.2 m/s) 1) the formula is applicable to \begin{document}$ {\mathrm{\Delta }T}_{m} $\end{document}>0 ℃

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      Table 3. Summary of test results for forced convection at low wind speed (Mirror velocity=0.2 m/s) 1) the formula is applicable to \begin{document}$ {\mathrm{\Delta }T}_{m} $\end{document}>0 ℃

      ModelMirror velocity/m·s−1$ {\Delta T}_{m} $/℃$ {r}_{0} $/cmStrehl ratioFWHM/(″)$ {F}_{r} $
      Forced convectionU=0.2018.510.980.03\ 1)
      0.215.600.970.040.18
      0.58.860.920.070.36
      0.82.990.780.210.18
      12.180.720.280.22
      1.51.750.620.360.40
      21.650.590.380.84
      2.51.520.540.411.39
      31.410.500.441.92
    • Table 4. Summary of test results for forced convection at high wind speed (Mirror velocity=1.0 m/s) 1) the formula is applicable to \begin{document}$ {{\Delta }T}_{m} $\end{document}>0 ℃

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      Table 4. Summary of test results for forced convection at high wind speed (Mirror velocity=1.0 m/s) 1) the formula is applicable to \begin{document}$ {{\Delta }T}_{m} $\end{document}>0 ℃

      ModelMirror velocity/m·s−1$ {\Delta T}_{m} $/℃$ {r}_{0} $ /cmStrehl ratioFWHM/(″)$ {F}_{r} $
      Forced convectionU=1.0015.380.940.04\ 1)
      0.221.460.960.030.06
      0.518.750.960.030.92
      0.814.610.940.044.23
      112.660.910.052.93
      1.54.040.890.156.63
      23.070.830.206.77
      2.52.640.790.248.84
      32.300.740.2710.8
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    Yan Wang, Yongxing Yang, Jinpeng Li, Yong Bi, Qingsheng Zhu. Experiment study on large solar telescope mirror seeing[J]. Infrared and Laser Engineering, 2024, 53(1): 20230412

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    Paper Information

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    Received: Aug. 1, 2023

    Accepted: --

    Published Online: Mar. 19, 2024

    The Author Email:

    DOI:10.3788/IRLA20230412

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