Solar Multi-conjugate Adaptive Optical System With High Resolution And Wide Field Of View

Atmospheric turbulence could lead to wave-front distortion of the original lightwave, consequently making the spatial resolution of optical telescopes to be far below the theoretical diffraction limit. Adaptive Optics(AO) technology enables real-time detection of wavefront aberrations, distortion correction, and consequently makes the spatial resolution of the telescope close to the diffraction limit. However, due to the atmospheric anisoplanatism, the field of view(FOV) of traditional adaptive optics is too small to meet the requirements of astronomical observation. In order to expand the FOV, the European Southern Observatory’s Beckers proposed multi-conjugation Adaptive optics(MCAO).In this paper, firstly, we have carried out the simulation of atmospheric refraction constant2 nC. Simulation indicates that the turbulence is mainly distributed in the Earth’s surface layer. As we know, Ground Layer Adaptive Optics(GLAO) technology is proposed for this type of turbulence. The FOV of Ground Layer Adaptive Optics ranges approximately range 1arcmin to 10 arcmin. Then, based on the research results of Ground Layer Adaptive Optics technology, we proposed to design a solar multi-conjugation Adaptive optical system with large field of view and high resolution to the observe activities of the Sun, which is an extended object.In order to explore the isoplanatic region of the system, we carried out a series of simulations.In the first, combined with atmospheric refractive-index constant in Hefei, the simulation of isoplanatic angle gains and diameter gain of isoplanatic region was carried out in diameter 1m telescope. Simulation indicates that, compared with conventional adaptive optics system, the system can expand the isoplanatic area.Further, based on three atmospheric turbulence models, the simulations of isoplanatic angle gain and diameter gain of isoplanatic region were done. The maximum values of isoplanatic angle gain of three models are almost the same, but the maximum values of the diameter gain of isoplanatic region of the three models are distinctly different. After an in-depth analysis, we concluded that the diameter gain of isoplanatic region could reflect the vertical distribution of the turbulence through the introduction of2 h, but isoplanatic angle gain could not. This indicates that isoplanatic region isrelated to the vertical distribution of atmospheric turbulence.Finally, we selected 10-and 30-meter diameter telescope, whose sizes are typical.Results showed that the isoplanatic region gains nearly 1. Deep analysis shows that the diameter increment is the main part of the increment of the FOV, diameter increment from the isoplanatic angle become less important. But this does not mean the system is not suitable for large telescopes. The system still can expand the FOV by guide stars.That’s why system using guide stars technology.Based on the demands and characteristics of solar observations, we throw light on the research the isoplanatic region. It is of great reference value on solar Adaptive Optics technology.