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首页> 外文会议>Conference on Future Giant Telescopes, Aug 26-28, 2002, Waikoloa, Hawaii, USA >20 and 30 m telescope designs with potential for subsequent incorporation into a track-mounted pair (20/20 or 30/30)
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20 and 30 m telescope designs with potential for subsequent incorporation into a track-mounted pair (20/20 or 30/30)

机译：20和30 m望远镜设计，有可能随后整合到轨道安装对中（20/20或30/30）

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Any future giant ground-based telescope must, at a minimum, provide foci for seeing-limited imaging over a wide field and for diffraction-limited imaging over ~1 arcminute fields corrected by adaptive optics (AO). While this is possible with a number of design concepts, our choices are constrained if we anticipate wanting to later add a second telescope for imaging with still higher resolution, and very high contrast imaging for exoplanet studies. This paper explores designs that allow for such future development. Higher resolution imaging by interferometric combination of the AO-corrected fields of two telescopes is possible without loss of point-source sensitivity or field of view, as long as the baseline can be held perpendicular to the source and varied in length. This requirement is made practical even for very large telescopes, provided both can move continuously on a circular track. The 20/20 telescope illustrates this concept. Telescopes so mounted can additionally be operated as a Bracewell nulling interferometer with low thermal background, making possible the thermal detection of planets that would have been unresolvable by a single 20 m aperture. In practice, limits set by funding and engineering experience will likely require a single 20 or 30 m telescope be built first. This would be on a conventional alt-az mount, but it should be at a site with enough room for later addition of a companion and track. In anticipation of future motion it should be compact and stiff, with a fast primary focal ratio. We envisage the use of large, highly aspheric, off-axis segments, manufactured using the figuring methods for strong aspher-ics already proven for 8 m class primaries. A compact giant telescope built under these guidelines should be able to perform well on its own for a broad range of astronomical observations, with good resistance to wind buffeting and simple alignment and control of its few, large segments. We compare here configurations with adjacent hexagonal segments and close-packed circular segments. For given segment parent size and number, the largest effective aperture is achieved if the segments are left as circles, when also the sensitivity and resolution for diffraction-limited operation with AO is higher. Large round segments can also be individually apodi/ed for high-contrast imaging of exoplanets with the entire telescope-for example 8.4 m segments will yield 10~(-6) suppression 0.05 arcsec from a star at 1 μm wavelength, and 0.25 arcsec at 5 μm.
机译：任何未来的巨型地面望远镜都必须至少提供焦点，以便在宽视场上进行有限视场成像，并在自适应光学系统（AO）校正的约1弧分场内为有限衍射视场成像。尽管许多设计理念都可以做到这一点，但如果我们希望以后再添加第二台望远镜以进行更高分辨率的成像，以及为系外行星研究提供非常高的对比度成像，则我们的选择将受到限制。本文探讨了允许这种未来发展的设计。只要基线可以垂直于放射源并保持其长度变化，就可以在不损失点源灵敏度或视场的情况下，通过干涉校正组合两台望远镜进行更高分辨率的成像。即使对于非常大的望远镜，只要两者都可以在圆形轨道上连续移动，这一要求就变得切实可行。 20/20望远镜说明了这一概念。如此安装的望远镜可以作为具有低热本底的Bracewell零干涉仪使用，从而可以对20 m的光圈无法分辨的行星进行热探测。在实践中，由资金和工程经验设定的限制可能需要首先制造一台20或30 m的望远镜。这将在常规的alt-az支架上进行，但是应该在有足够空间的位置，以便以后添加伴奏和音轨。在预期将来的运动时，它应该紧凑，坚固，并具有快速的主焦比。我们设想使用大的，高度非球面的，离轴的扇形段，这些扇形段是使用已针对8 m级原色经过验证的强力球体的计算方法制造的。根据这些指导方针制造的紧凑型巨型望远镜应该能够独自发挥出色的性能，可以进行广泛的天文观测，并且具有良好的抗风振性能，并且可以对少数几个大型部分进行简单的对准和控制。我们在这里将配置与相邻的六边形段和密排圆形段进行比较。对于给定的段父尺寸和数量，如果将段保留为圆形，则可获得最大的有效孔径，而使用AO进行衍射限制操作的灵敏度和分辨率也更高。大的圆形部分也可以单独使用，以对整个望远镜的系外行星进行高对比度成像，例如8.4 m的部分将从1μm波长的恒星产生10〜（-6）抑制0.05弧秒，在0.25 sec时产生0.25弧秒。 5微米

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