Beesley L F, Osborn J, Wilson R, Farley O J D, Griffiths R, Love G D
Appl Opt. 2024 Jun 1;63(16):E48-E53. doi: 10.1364/AO.519063.
We present measurements of the atmospheric optical turbulence as a function of zenith angle using two identical instruments, Shack-Hartmann Image Motion Monitors (SHIMMs), to measure atmospheric parameters concurrently. One instrument was pointed near zenith, while the other collected data by tracking a single star until it set and thus sampling zenith angles continuously to the horizon. By comparing these measurements, we can attribute changes in the atmospheric parameters to the changing zenith angle rather than variations in local turbulence conditions. The primary purpose of this experiment is to make comparisons between the measurements of the scintillation index, 2, and Fried parameter, , with current theories. In this demonstration, we find that there is a strong agreement between the models and the instrument up until zenith angles of 70, above which model and measurements begin to deviate. We discuss various ways in which limitations in models and our instrument may cause these deviations.
我们使用两台相同的仪器——夏克-哈特曼图像运动监测仪（SHIMM），同时测量大气参数，以此展示大气光学湍流作为天顶角函数的测量结果。一台仪器指向天顶附近，而另一台通过跟踪一颗恒星直至其落下，从而连续采样直至地平线的天顶角来收集数据。通过比较这些测量结果，我们可以将大气参数的变化归因于天顶角的变化，而非局部湍流条件的变化。本实验的主要目的是将闪烁指数（$\sigma^2$）和弗里德参数（$r_0$）的测量结果与当前理论进行比较。在本次演示中，我们发现直到天顶角为70°时，模型与仪器之间都有很强的一致性，在该角度以上，模型与测量结果开始出现偏差。我们讨论了模型和我们仪器的局限性可能导致这些偏差的各种方式。
