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

• Published in: Monthly notices of the Royal Astronomical Society Vol. 419; no. 4; pp. 3406 - 3413
• Main Authors: Su, Ding-qiang, Jia, Peng, Liu, Genrong
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2012; Wiley-Blackwell; Oxford University Press
• Subjects: Astronomy; atmospheric effects; Earth, ocean, space; Exact sciences and technology; instrumentation: spectrographs; surveys; techniques: spectroscopic; Telescopes; surveys; instrumentation: spectrographs; atmospheric effects; techniques: spectroscopic; telescopes; Optical fibers; Diffraction; atmospheric effects-instrumentation: spectrographs; Diameter
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2011.19979.x

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.