Polarimetric Littrow Spectrograph - instrument calibration and first measurements
Polarimetric Littrow Spectrograph - instrument calibration and first measurements
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DOI：
10.1051/0004-6361:20052662
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发表时间：
2005-07
影响因子：
6.5
通讯作者：
C. Beck;W. Schmidt;T. Kentischer;D. Elmore
中科院分区：
文献类型：
--
作者：
C. Beck;W. Schmidt;T. Kentischer;D. Elmore
我们提出的第一次测量和校准程序的偏振利特罗光谱仪（POLIS）在特内里费岛的真空塔望远镜，连同仪器的技术特点的简要总结。在其目前的配置中，我们实现了约3 × 10 - 3的偏振精度在可见光通道（630 nm）的仪器。精度受到不同偏振态之间串扰的限制。偏振光的检测极限约为2 × 10^{-3}$，曝光时间为7 s。在蓝色通道（$\ion{Ca}{ii}$ H线，396.7 nm）的偏振测量受到低光子通量的强烈限制。在这个波长下，我们给出了空间分辨率约为0.5弧的Stokes- V图.任何分光偏振计的偏振质量都受到仪器校准精度的限制。我们提出了一种新的方法进行自校准，减少串扰之间的偏振组件为0.1%。这种改进是由于校准波片的延迟测量精度为0.1°。我们展示了同时使用POLIS和特内里费岛红外偏振仪的能力，该偏振仪集成在真空塔望远镜的主摄谱仪中。
We present first measurements and the calibration procedure for the Polarimetric Littrow Spectrograph (POLIS) operated at the Vacuum Tower Telescope on Tenerife, together with a brief summary of the technical characteristics of the instrument. In its present configuration, we achieve a polarimetric accuracy of about $3 \times 10^{-3}$ in the visible channel (630 nm) of the instrument. The accuracy is limited by cross talk among the different polarization states. The detection limit for polarized light is about $2 \times 10^{-3}$ for a 7 s exposure. Polarimetric measurements in the blue channel ($\ion{Ca}{ii}$ H line, 396.7 nm) are strongly limited by the low photon flux. At this wavelength we present Stokes- V maps with a spatial resolution of about 0.5 arcs. The polarimetric quality of any spectropolarimeter is limited by the precision of the instrument calibration. We present a new method for self-calibration that reduces cross talk among the polarization components to 0.1%. This improvement results from a measurement of the retardance of the calibration waveplate with an accuracy of 0.1°. We demonstrate the capability of the simultaneous use of POLIS and the Tenerife Infrared Polarimeter which is integrated in the main spectrograph of the Vacuum Tower Telescope.