LARS: An Absolute Reference Spectrograph for solar observations Upgrade from a prototype to a turn-key system
LARS: An Absolute Reference Spectrograph for solar observations Upgrade from a prototype to a turn-key system
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DOI：
10.1051/0004-6361/201731164
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发表时间：
2017-07
影响因子：
6.5
通讯作者：
J. Löhner-Böttcher;W. Schmidt;H. Doerr;T. Kentischer;T. Steinmetz;R. Probst;R. Holzwarth
中科院分区：
文献类型：
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作者：
J. Löhner-Böttcher;W. Schmidt;H. Doerr;T. Kentischer;T. Steinmetz;R. Probst;R. Holzwarth
LARS是为超精密太阳观测而设计的绝对参考光谱仪。真空塔望远镜的高分辨率梯形光谱仪由最先进的激光频率梳支撑，可以在绝对波长尺度上校准太阳光谱。在这篇文章中，我们描述了科学仪器，并集中在过去两年的升级，将原型转化为交钥匙系统。所追求的目标是提高系统的短期和长期稳定性，并使该仪器的操作更方便、更灵活。第一次升级涉及频率梳的现代化。法布里-珀罗腔被调整到8 GHz的重复频率。实现了技术成熟的光子晶体光纤的光谱展宽。第二次，也是最近的一次升级，是在将太阳光送入连接到光谱仪的单模光纤的光学装置上进行的。部署了一个机动平移工作台，以允许自动选择直径为1“、3”和10“的三种不同视场来分析太阳光谱。成功的升级允许每天长达几个小时的长期观测，稳定的光谱精度为1米/S，受光谱仪限制。支持仪器稳定、用户友好的操作。选择预对准光纤来改变视场现在可以在几秒钟内完成。LARS提供了观测太阳大气中谱线和多普勒速度的绝对波长位置的可能性。第一批结果证明了该仪器用于太阳科学的能力。对太阳对流、p模和大气波的精确测量将增强我们对太阳大气及其物理条件的了解，从而改进现有的大气模型。
LARS is an Absolute Reference Spectrograph designed for ultra-precise solar observations. The high-resolution echelle spectrograph of the Vacuum Tower Telescope is supported by a state-of-the-art laser frequency comb to calibrate the solar spectrum on an absolute wavelength scale. In this article, we describe the scientific instrument and focus on the upgrades in the last two years to turn the prototype into a turn-key system. The pursued goal was to improve the short-term and long-term stability of the systems, and enable a user-friendly and more versatile operation of the instrument. The first upgrade involved the modernization of the frequency comb. The Fabry-Perot cavities were adjusted to filter to a repetition frequency of 8GHz. A technologically matured photonic crystal fiber was implemented for spectral broadening. The second, quite recent upgrade was performed on the optics feeding the sunlight into a single-mode fiber connected to the spectrograph. A motorized translation stage was deployed to allow the automated selection of three different fields-of-view with diameters of 1", 3", and 10" for the analysis of the solar spectrum. The successful upgrades allow for long-term observations of up to several hours per day with a stable spectral accuracy of 1 m/s limited by the spectrograph. Stable, user-friendly operation of the instrument is supported. The selection of the pre-aligned fiber to change the field of view can now be done within seconds. LARS offers the possibility to observe absolute wavelength positions of spectral lines and Doppler velocities in the solar atmosphere. First results demonstrate the capabilities of the instrument for solar science. The accurate measurement of the solar convection, p-modes, and atmospheric waves will enhance our knowledge of the solar atmosphere and its physical conditions to improve current atmospheric models.