抚仙湖太阳观测和研究基地知识库

1 m新真空太阳望远镜的成像系统包括Hα,CaⅡ和He Ⅰ三个窄带成像通道,三者均使用里奥滤光器系统进行单色像观测。以Hα通道实测图像为例,探讨了在线心一线翼的偏带观测出现的太阳像亮度空间分布不均匀问题的原因。该不均匀性不同于杂散光.其空间分布形式与变化程度随观测波长点的不同而不同。通过对多组实测数据的分析认为.出现亮度不均现象的根本原因是滤光器的视场效应.视场边缘区域的工作波长相对中心区域发生频率漂移。频漂的程度和空间分布特征与光路装调密切相关,通过分析对比2017年3月光路调整前后频漂情况得出结论:在目前Hα成像通道2.2’的视场范围内,视场频漂量最大为0.005 nm,小于透过带带宽,且仅出现在视场左下角边缘。

The working wavelength of the High-Resolution Imaging System operated at 1-meter New Vacuum Solar Telescope (NVST) includes 3 narrow-band wavelength: Ha (6562.8A), Ca II (3933A) and He I (10830A). The monochromatic observation of these 3 wavelength is implemented by tunable Lyot filters. This paper analyses the phenomenon of the spaeial non-unifrom intensity distribution of solar images at different off-bands based on observed data at the wavelength of 6562.8A (Ha channel). This non-uniform distribution is different to the stray light, for its spatial distribution and variation changes at different off-bands. The analysis of multiple sets of observation data shows the FOV effect of the Lyot filter results in this phenomenon, that the working wavelength at the edge of the FOV deviates from that at the centre of FOV and the degree of the wavelength shift depends on the accuracy of the optical installation. The wavelength shift at different part of the FOV of Ha channel is obtained and compared by the data before the optical adjustment in March 2017, and the result shows that within the 2.2' FOV of the Ha channel, the maximum wavelength shift is 0.05A, which is less than the passband of this Lyot filter (0.25A), and is located at the left corner of the FOV.