Atmospheric dispersion corrector for the Large Sky Area Multi-Object Fibre Spectroscopic Telescope

Authors

  • Ding-qiang Su,

    Corresponding author
    1. Department of Astronomy, Nanjing University, 22 Hankou Road, Nanjing 210093, China
    2. Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, China
    3. National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology (NIAOT), Chinese Academy of Science, 188 Bancang Street, Nanjing 210042, China
      E-mail: dqsu@nju.edu.cn
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  • Peng Jia,

    1. Department of Astronomy, Nanjing University, 22 Hankou Road, Nanjing 210093, China
    2. Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, China
    3. National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology (NIAOT), Chinese Academy of Science, 188 Bancang Street, Nanjing 210042, China
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  • Genrong Liu

    1. National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology (NIAOT), Chinese Academy of Science, 188 Bancang Street, Nanjing 210042, China
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E-mail: dqsu@nju.edu.cn

ABSTRACT

The Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) is the largest, wide field-of-view (FOV) telescope (with an aperture of 4 m), and it is equipped with the highest number (4000) of optical fibres in the world. For the LAMOST North and the LAMOST South, the FOVs are 5° and 3.5°, respectively, and the linear diameters are 1.75 m and 1.22 m, respectively. A new type of atmospheric dispersion corrector (ADC) is put forward and designed for LAMOST. It is a segmented lens, which consists of many lens–prism strips. Although it is very large, its thickness is only 12 mm. Thus, the difficulty of obtaining a large optical glass is avoided, and the aberration caused by the ADC is small. By moving this segmented lens along the optical axis, different dispersions can be obtained. We discuss the effects of ADC’s slits on the diffraction energy distribution and on the obstruction of light. We calculate and discuss the aberration caused by the ADC. All these results are acceptable. Such an ADC could also be used for other optical fibre spectroscopic telescopes, especially those which a have very large FOV.

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