arXiv subjects

Ding-qiang Su

Publications and source records attributed to Ding-qiang Su.

3 recordsLinked to original sources

arXiv2024

Optical system for extremely large spectroscopic survey telescope

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.

astro-ph.IM↗

arXiv2019

Suggested quasi Cassegrain system for multi-beam observation of FAST

FAST, the largest single-dish radio telescope in the world, has a 500-meter diameter main reflector and a 300-meter diameter illumination area. It has a shape variable main reflector, which changes the shape of the illuminated area in the main reflector into a paraboloid continuously. In this article, we propose a quasi Cassegrain system to FAST. The detailed design results are given in this paper. Such a quasi Cassegrain system only needs to add a 14.6-meter diameter secondary reflector, which is close to the size of the feed cabin, the distance from the secondary reflector to the focus is only 5.08-meter, and it has excellent image quality. In this quasi Cassegrain system the shape of the illuminated area in the main reflector continuously changes into an optimized hyperboloid. Using this quasi Cassegrain system from frequency 0.5 G to 8 G, the multi-beam system can include 7 to 217 feeds. If this system is used in combination with PAF technology, more multi-beam feeds can be used.

astro-ph.IM↗

arXiv2011

The atmospheric dispersion corrector for the Large Sky Area Multi--object Fibre Spectroscopic Telescope (LAMOST)

The Large Sky Area Multi--object Fibre Spectroscopic Telescope (LAMOST) is the largest (aperture 4 m) wide field of view (FOV) telescope and is equipped with the largest amount (4000) of optical fibres in the world. For the LAMOST North and the LAMOST South the FOV are 5 deg and 3.5 deg, the linear diameters are 1.75 m and 1.22 m, respectively. A new kind 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 big, its thickness is only 12 mm. Thus the difficulty of obtaining big optical glass is avoided, and the aberration caused by the ADC is small. Moving this segmented lens along the optical axis, the different dispersions can be obtained. The effects of ADC's slits on the diffraction energy distribution and on the obstruction of light are discussed. The aberration caused by ADC is calculated and discussed. 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.

astro-ph.IM↗