Ground-based telescope imaging model is developed in this paper, the relationship between the atmospheric disturbances and the ground-based telescope image quality is studied. Simulation of the wave-front distortions caused by atmospheric turbulences has long been an important method in the study of the propagation of light through the atmosphere. The phase of the starlight wave-front is changed over time, but in an appropriate short exposure time, the atmospheric disturbances can be considered as “frozen”. In accordance with Kolmogorov turbulence theory, simulating atmospheric disturbances of image model based on the phase screen distorted by atmospheric turbulences is achieved by the fast Fourier transform (FFT). Geiger mode avalanche photodiode array (APD arrays) model is used for atmospheric wave-front detection, the image is achieved by inversion method of photon counting after the target starlight goes through phase screens and ground-based telescopes. Ground-based telescope imaging model is established in this paper can accurately achieve the relationship between the quality of telescope imaging and monolayer or multilayer atmosphere disturbances, and it is great significance for the wave-front detection and optical correction in a Multi-conjugate Adaptive Optics system (MCAO).
SONG (Stellar Oscillation Network Group) is an international project to form a global observing network of eight 1- meter class telescopes. China joined this project and funded one node telescope for this network. By the end of 2013, the Chinese SONG telescope has been installed on the Delinha observing site of Purple Mountain Observatory in Qinghai province. This paper will give the introduction of this telescope, including its optical system, structure and control system. Besides, the preliminary observing performance of the telescope on site will be given in the second part of this paper.
SONG is initiated by Danish to design, build, and utilize a global network of eight 1-meter class telescopes to be
operated as a whole-Earth telescope. China has joined the international SONG project in 2009 and will build one 1-meter
telescope as the node of SONG global network in China. Now the telescope is during the period of building. This paper
will give an introduction of Chinese SONG telescope, including telescope requirements, telescope design and other
The paper reports optical system of a 1 meter diameter telescope dedicated to Stellar Observations
Network Group (SONG) for the National Astronomical Observatories, CAS. SONG is an international
cooperative project, Optimize the design for Asteroseismology purposes. According to the prototype of
SONG, Chinese SONG telescope includes Cassegrain telescope, Nasmyth platform, Coudé train,
Coudé focal plane, Shack-Hartmann wavefront sensor and spectrograph. The telescope will provide a
field of view of 65 arcsec at the Nasmyth F/36.67 focus, 10 arcsec at the F/6 Coudé focus. The rotating
tertiary mirror directs the light to the two Nasmyth foci, one for Shack-Hartmann wavefront sensor, the
other for Nasmyth platform and spectrograph.
The standard SONG node structure of control system is presented. The active optical control system of the project is a
distributed system, and a host computer and a slave intelligent controller are included. The host control computer collects
the information from wave front sensor and sends commands to the slave computer to realize a closed loop model. For
intelligent controller, a programmable logic controller (PLC) system is used. This system combines with industrial
personal computer (IPC) and PLC to make up a control system with powerful and reliable.
A novel laser ranging method use Geiger mode APD (avalanche photodiode) array is introduced in this paper. In the
proposed method, echo signal is received by APD arrays at gate mode, system fulfill photon counting, curve recover,
start-point distinguish, determine the distance of target ultimately. The results show that with this method, we can get a
higher precision, farther distance with less laser power, comparing with the traditional laser ranging methods. So a new
thinking way for the laser ranging is provided.