Optical design of Gemini Altair
Optical design of Gemini Altair
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Gemini Altair 光学设计
DOI：
10.1117/12.321718
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
J. Pazder
中科院分区：
文献类型：
--
作者：
E. Richardson;J. M. Fletcher;C. Morbey;J. Oschmann;J. Pazder
8米双子座望远镜的自适应光学（AO）模块Altair是“透明的”，因为它不会改变焦比，即f/16输入和f/16输出；它具有与裸望远镜相同的焦点位置，出射光瞳的变化微不足道。然而，Altair 具有平坦的焦面，与其他 AO 设计不同，其他 AO 设计的焦面比裸望远镜的焦面弯曲程度更大，且方向相反。 Altair 的一个不寻常的要求是，望远镜上方 6.5 公里的大气层应成像到可变形镜上。其他要求是波前传感器模块中的畸变最小化，用于将可变形镜成像到小透镜阵列上，以及将大约 230 个小透镜的图像重新成像到 CCD 上，适用于自然导星，以及物距范围为 85 公里至 156 公里的钠激光导星。自然星束和激光星束的分离是通过将聚焦的自然星像穿过一个针孔来实现的，该针孔比倾斜针孔镜反射的失焦激光束中望远镜副镜的阴影更小。
The 8-meter Gemini telescope's adaptive optics (AO) module, Altair, is 'transparent' in that it does not change the focal ratio, being f/16 in and f/16 out; it has the same focal position as the bare telescope, with insignificant change in the exit pupil. However, Altair has a flat focal surface, unlike other AO designs which have focal surfaces curved more than the focal surface of the bare telescope and in the opposite direction. An unusual requirement for Altair is that the atmospheric layer 6.5 km above the telescope should be imaged onto the deformable mirror. Other requirements are minimization of distortion in the wavefront sensor module for both the imaging of the deformable mirror onto the lenslet array and for the reimaging of the approximately 230 lenslets' images onto a CCD, for a natural guide star, and also for a Sodium laser guide star ranging in object distance form 85 km to 156 km. The separation of natural and laser star beams is done with minimum light loss by passing the in-focus natural star image through a pinhole which is smaller than the shadow of the secondary mirror of the telescope in the out-of-focus laser beam which is reflected by the tilted pinhole mirror.