大气湍流对中红外ELT自适应光学的影响
Atmospheric refractivity effects on mid-infrared ELT adaptive optics
摘要：
讨论了大气色散对中红外自适应光学辅助仪器性能的影响。色散和大气色度通常被认为在该波长范围内是可忽略的。它在这里示出，然而，与大大减少衍射极限尺寸ELT和衍射限制性能的需要，在这样的仪器的设计和操作中，应仔细考虑双折射现象。我们包括一个概述的理论，红外线的活动，以及大气中的水蒸气和其他成分的存在所造成的红外共振的影响。“传统”大气色散可能仅在最短波长（L波段）处导致斯特列尔损失。更可能的误差来源是波前被感测和校正的波长的差异，导致波前传感器和科学仪器之间的指向偏移，其在长时间曝光中随着时间而演变。红外辐射还受到大气中存在的水蒸气所造成的额外湍流的影响，而这种湍流是可见波阵面传感器所看不到的，人们对其影响知之甚少。我们利用在无线电波长获得的信息，使其对中红外地面仪器的性能的影响的一阶估计。本文中的计算是使用两个不同地点的参数进行的，一个是“标准好地点”，一个是“高干旱地点”，以说明选择ELT地点的重要性。
英文摘要：
We discuss the effect of atmospheric dispersion on the performance of a mid-infrared adaptive optics assisted instrument on an extremely large telescope (ELT). Dispersion and atmospheric chromaticity is generally considered to be negligible in this wavelength regime. It is shown here, however, that with the much-reduced diffraction limit size on an ELT and the need for diffraction-limited performance, refractivity phenomena should be carefully considered in the design and operation of such an instrument. We include an overview of the theory of refractivity, and the influence of infrared resonances caused by the presence of water vapour and other constituents in the atmosphere. `Traditional' atmospheric dispersion is likely to cause a loss of Strehl only at the shortest wavelengths (L-band). A more likely source of error is the difference in wavelengths at which the wavefront is sensed and corrected, leading to pointing offsets between wavefront sensor and science instrument that evolve with time over a long exposure. Infrared radiation is also subject to additional turbulence caused by the presence of water vapour in the atmosphere not seen by visible wavefront sensors, whose effect is poorly understood. We make use of information obtained at radio wavelengths to make a first-order estimate of its effect on the performance of a mid-IR ground-based instrument. The calculations in this paper are performed using parameters from two different sites, one `standard good site' and one `high and dry site' to illustrate the importance of the choice of site for an ELT.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
