低灵敏度空间引力波望远镜光学系统设计

Design of optical system for low-sensitivity space gravitational wave telescope

太极计划是中国探测空间引力波的一项重点任务。望远镜作为空间引力波探测中的重要组成部分,它的性能会直接影响引力波探测的精度。现有的典型空间引力波望远镜结构中次镜灵敏度高,难以满足更大口径的空间引力波望远镜对制造装调公差的要求,特别是在轨稳定性公差要求。为解决以上问题,首先,提出了一种中间像面设置于三四镜之间的新型空间引力波望远镜光学系统结构,以降低次镜灵敏度;结合高斯光学理论方法,从理论上分析并计算新型望远镜结构的初始参数。其次,通过优化设计,获得入瞳直径为400 mm,放大倍率为80倍,科学视场为±8μrad,波前误差RMS值优于0.0063λ的望远镜光学系统。最后,建立了望远镜系统的灵敏度评价公差分配表,对比分析了现有望远镜结构与新型望远镜结构的公差情况。结果显示:相较于现有望远镜结构,新型望远镜结构的灵敏度降低了30.4%,具有低灵敏度优势,为空间引力波望远镜的设计提供了一种优选方案。

The Taiji program is a key task for China's space gravitational wave detection,and as an import-ant part of space gravitational wave detection,the telescope's performance will directly affect the accuracy of gravitational wave detection.For the existing typical space gravitational wave telescope structures,due to the high sensitivity of secondary mirror,it is difficult to meet the requirements for manufacturing and adjustment tolerance of larger aperture space gravitational wave telescopes,especially the tolerance requirements for in-orbit stability.In order to solve the above problems,firstly,a new optical system structure of space gravitational wave telescope with intermediate image plane set between three and four mirrors is proposed to reduce the sensitivity of the secondary mirror.Combined with the theoretical method of Gaussian optics,the initial parameters of the structure of the new telescope are theoretically analyzed and calculated.Secondly,through the optimization design,a telescope optical system with a pupil diameter of 400 mm,a magnification of 80 times,a field of view of±8μrad,and a wavefront error RMS value of better than 0.0063λwas obtained.Finally,the sensitivity evaluation tolerance allocation table of the telescope system is established,and the tolerances of the existing telescope structure and the new telescope structure are compared and analyzed.Compared with the existing telescope structure,the sensitivity of the new telescope structure is reduced by 30.4%.The results show that the new telescope structure has the advantage of low sensitivity,which provides an optimal scheme for the design of space gravitational wave telescopes.