An off-axis Golay3 sparse aperture telescope with a freeform secondary mirror
The application of freeform surface in an optical system can effectively increase the freedom of optical design and reduce the number of optical elements. In this work, a two-mirror off-axis sparse aperture telescope is proposed. The primary mirror is made of three sub-mirrors arranged in the Golay3 configuration while the secondary is a freeform surface defined by a polynomial of two variables X and Y. The off-axis configuration is used to remove the obstruction of the secondary mirror. The results indicate that the fill factor of the Golay3 primary mirror increases to 58.4%, which is significantly higher than that of the on-axis configuration. The image quality is improved within 2.5° full field of view from its spot diagram, distortion, modulation transfer function, and encircled energy.
KeywordsSparse aperture Freeform Field of view Fill factor
This work is supported partially by National Science Foundation of China (NSFC) (61875145, 11804243); Jiangsu Province Key Discipline of China’s 13th 5-year plan (20168765); Jiangsu Key Laboratory of Advanced Optical Manufacture Technology (KJS1710); Suzhou Key Laboratory (SZS201611, SZS201712); and the Six Talent Peaks Project of the Jiangsu Province (DZXX-026). The authors are also grateful to Professor Qian Lin of Soochow University for valuable advices and to Dr. Cao Zongjian of Augusta University in USA for editorial suggestions.
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