Open loop adaptive optics testbed on 2.16 meter telescope with liquid crystal corrector

A novel liquid crystal wave front corrector (LCWFC) based open loop adaptive optics testbed for nonpolarized light was introduced in this paper. A polarizing beam splitter (PBS) was used behind the LCWFC to divide the reflected nonpolarized light into two orthogonal polarized lights with and without the modulation effect for high resolution imaging and aberration detection respectively. The alignment direction of LC molecules was parallel to the polarization direction of the light PBS reflected. This configuration was simple and easy for construction. It avoided the energy loss due to the use of polarizer for conventional LCWFC based closed loop adaptive optics system. Furthermore, it could be switched into closed loop configuration very easily, which was useful for quantitative system performance evaluation. The detailed construction and operation was reported in Section 2. In Section 3, this testbed was deployed at the coude focus of the 2.16 m telescope at the Xinglong Station of the Beijing Astronomical Observatory. The observation of star Arcturus was done. The Full Width Half Maximum (FWHM) resolution was improved from 2.12 '' to 0.64 '' successfully. (C) 2011 Elsevier B.V. All rights reserved.