Optical system for extremely large spectroscopic survey telescope

• Published in: Science China. Physics, mechanics & astronomy mechanics & astronomy, 2024-07, Vol.67 (7), p.279511, Article 279511
• Main Authors: Su, Ding-qiang, Bai, Hua, Yuan, Xiangyan, Cui, Xiangqun
• Format: Article
• Language: English
• Subjects: Astronomy; Atmospheric correction; Atmospheric diffusion; Classical and Continuum Physics; Dispersion; Image quality; Observations and Techniques; Optical glass; Physics; Physics and Astronomy; Pollution dispersion; Spectroscopy; Telescopes
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-023-2316-3

This article presents research work on a spectroscopic survey telescope. Our idea is as follows: for such a telescope, a pure reflecting optical system is designed, which should have an aperture and a field of view (FOV) both as large as possible and excellent image quality, and then a strip lensm (lens-prism) atmospheric dispersion corrector (S-ADC) is added, only for correcting the atmospheric dispersion. Given the fund limitation and the simplicity of scaling up, some 12-m telescopes are designed as examples. Su, Korsch, and Meinel put forward the four-mirror Nasmyth systems I and II, which are used in this paper. FOVs of 1.5°, 2°, and 2.5° are selected. For all systems, the image qualities are excellent. Because the S-ADC relaxes the optical glass size restriction, this 12-m telescope with a FOV of 2.5° can be magnified in proportion to a 16-m telescope. Its etendue (from French étendue) and focal surface will now be the largest in the world. In such a telescope, a pure reflecting optical system can also be obtained. A subsequent coudé system is designed with excellent image quality.