Asgard/NOTT：实验室消光干涉性能状态
Asgard/NOTT: Status of laboratory nulling performance
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中文总结 AI 辅助
Asgard/NOTT消光干涉仪针对L'波段开展环境性能评估，发现当前消光性能恶化，计划通过改进测试台、安装低温恒温器等提升性能并重新评估。
中文摘要 AI 辅助
消光干涉测量技术可实现对经典衍射极限成像仪无法分辨的角距处的微弱伴星和星周结构的直接探测，同时大幅提升可测量的对比度。Asgard/NOTT消光干涉仪旨在在L'波段（3.5-4.0μm）达到10^-5的对比度性能，从而实现对雪线附近的年轻巨系外行星和热外黄道尘埃的观测与表征。此前的研究已在环境条件下验证了芯片的消光能力，以及在低温条件下验证了测试台的消光能力。本研究旨在首次对测试台在光谱分散光条件下开展环境性能评估。对数据采集与校准流水线进行了必要修正，开展、建模并拟合了条纹扫描。此外，在测试台上表征了4望远镜消光合束器（一种光子型镓硫化镧（GLS）芯片）的分光比，显示其与此前的芯片表征结果初步吻合。当前消光性能出现恶化，达到的对比度约为10^-1，比此前表征的性能高出一个数量级。对测试台和所采用方法的多项未来改进有望提升性能表征效果，特别是将故意使输入光束强度失配，以应对定向耦合器不平衡的分光比。随着最终低温恒温器和相机的安装，所开发的工具将被用于重新评估环境和低温条件下的性能。
英文摘要
Nulling interferometry enables the direct detection of faint companions and circumstellar structures at angular separations unresolvable by classical, diffraction-limited imagers, whilst dramatically improving the measurable contrast. The Asgard/NOTT nulling instrument aims to achieve a contrast performance of 10^-5 in the L' wavelength band (3.5 - 4.0 μm), enabling observation and characterization of young giant exoplanets near the snowline and hot exozodiacal dust. Previous studies have verified the nulling capabilities, of the chip in ambient conditions and of the test bench in cryogenic conditions. This work aims to add the first ambient performance assessment of the test bench with spectrally dispersed light. Necessary revisions are made to the data acquisition and calibration pipeline and fringe scans are carried out, modeled and fitted. The splitting ratios of the 4-telescope nulling beam combiner, a photonic Gallium Lanthanum Sulfide (GLS) chip, are moreover characterized on the bench, showing tentative agreement with previous chip characterization. The null performance has worsened, the achieved contrast of ~ 10^-1 being one order of magnitude higher than what earlier characterized performance showed. Multiple future changes to the test bed and to the approach taken promise an improved characterization of performance. In particular, the input beam intensities will be deliberately mismatched to account for the imbalanced splitting ratios of the directional couplers. With the installation of the final cryostat and camera, the developed tools will be leveraged to re-assess the performance in ambient and cryogenic conditions.
