Analysis On Optic Axis Deviation Induced By Lens Position Disorder Of 1m New Vacuum Solar Telescope

In order to satisfy the telescope image quality requirements, even a well-processed advanced large optical telescope up to standard in factory must be tested after installation and commissioning. For large telescopes, slight decentration or tilt of the optical imaging components(such as the primary mirror and the secondary mirror) can cause the optical axis deviation. This deviation not only brings trouble to the telescope pointing, but also reduces effective visual field. We noticed that decentration and tilt can sometimes compensate each other, mitigating damage of telescope imaging quality. Therefore, traditional comprehensive quality-standard test method for final assessment is not complete. This paper describes this problem and a new method, computer-aided alignment technique, is used. The main process of this method includes aberration test, calculating direction and magnitude of the mirrors model, and installing the mirrors according to the above parameters. This process will be repeated until the quality of the image meets the requirements. The precision of the model ensure the correctness and uniqueness of the convergence result.1m New Vacuum Solar Telescope(NVST) of the Yunnan Observatories located in the northeastern coast of Yunnan Chengjiang Fuxian Lake Eagles Land(longitude 102°57?11?,latitude 24°34?47?),which has a world-class atmospheric seeing.Taking the NVST of the Yunnan Observatories as an example, we discuss the influence of the above errors on the optical axis and the field of view and conclude that the optical axis stability is a necessary index to test the results of large telescope alignment.