Status update of LLAMAS: a wide field-of-view visible passband IFU for the 6.5m Magellan telescopes
Status update of LLAMAS: a wide field-of-view visible passband IFU for the 6.5m Magellan telescopes
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LLAMAS 状态更新：适用于 6.5m 麦哲伦望远镜的宽视场可见光通带 IFU
DOI：
10.1117/12.2562803
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Coppeta, David
中科院分区：
文献类型：
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作者：
Furész, Gábor;Simcoe, Robert A.;Egan, Mark D.;Malonis, Andrew;Masterson, Rebecca A.;Brown, Joshua;Cappiello, Gregory;Chesbrough, Christian;Clark, Kristin;Coppeta, David
大透镜阵列麦哲伦摄谱仪（LLAMAS）是美国国家科学基金会资助的设施级积分场单元（IFU）摄谱仪，正在为6.5米麦哲伦望远镜建造。 它覆盖了37”x 37”的立体角，具有通过双面微透镜阵列有效耦合的2，400根光纤，产生R = 2，000的光谱，空间分辨率为0.7511。它的宽通带从λ = 350 - 970 nm提供了访问线和连续测量在很宽的范围内的红移。使用说明书将光复用到8台紧凑型碳纤维台式光谱仪中，该光谱仪采用VPH光栅。我们在优化LLAMAS系统设计的同时，采用了多项性价比交易，包括：（a）在具有适度入射光瞳的3个快速全折射相机系统之间分割通带，（B）限制每单位的光纤（即狭缝长度）和建造更多的光谱仪以利用产量，以及（c）使用围绕普通检测器（e2 v 42-40）构建的商业CCD相机和热电+液体冷却。为了提高蓝光通量并实现高质量的天空相减，光谱仪集群安装在折叠卡塞格伦端口的焦平面旁边，具有重力不变的支持。这也使仪器能够快速部署，并在任何夜晚在10分钟内完全可用，作为观测天体物理瞬变的设施单元。于二零二零年三月向Magellan交付了一个小型IFU（169根光纤），安装在一个全尺寸前端包装中，配有一台光谱仪（2台摄像机）。尽管由于COVID-19大流行而不幸取消了空中调试，但我们展示了该原型的实测实验室性能。因此，这方面的贡献集中在随后的设计演变和状态的完整设施仪器。
The Large Lenslet Array Magellan Spectrograph (LLAMAS) is an NSF-funded facility-class Integral Field Unit (IFU) spectrograph under construction for the 6.5-meter Magellan Telescopes. It covers a 37" x 37" solid angle with 2,400 optical fibers efficiently coupled by a double-sided microlens-array, producing R = 2, 000 spectra with 0.7511 spatial resolution. Its broad passband from λ = 350 970nm offers access to line and continuum measurements over a wide range in redshift. Light is multiplexed by the IFU into 8 compact, carbon-fiber bench mounted spectrographs utilizing VPH grisms. We employed several trades on cost-performance ratio while optimizing LLAMAS’ system design including: (a) Splitting the passband between 3 fast all-refractive camera systems with modest entrance pupils, (b) limiting the fibers per unit (i.e. slit length) and building more spectrographs to leverage on production volume, and (c) using a commercial CCD camera built around a common detector (e2v 42-40) and thermoelectric + liquid cooling. To boost blue throughput and achieve high-quality sky subtraction the spectrograph cluster is mounted next to the focal plane on a folded Cassegrain port with gravity-invariant support. This also allows the instrument to deploy quickly, and be fully accessible within 10 minutes on any night, serving as a facility unit for observing astrophysical transients. A sub-sized IFU (169 fibers), mounted in a full-sized front end package with a single spectrograph (2 cameras) was delivered to Magellan in March 2020. We present as-measured laboratory performance from this prototype, though on-sky commissioning was unfortunately cancelled because of the COVID-19 pandemic. This contribution therefore focuses on subsequent design evolution and status of the full facility instrument.