A Near Infrared Integral Field spectrograph (NIR) for the Southern African Large Telescope (SALT): mechanical design
A Near Infrared Integral Field spectrograph (NIR) for the Southern African Large Telescope (SALT): mechanical design
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用于南部非洲大型望远镜 (SALT) 的近红外积分场光谱仪 (NIR)：机械设计
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发表时间：
2018
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通讯作者：
Elijah Ruder
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作者：
Michael P. Smith;M. Wolf;M. Bershady;D. Adler;K. Jaehnig;Ron J. Koch;M. Mulligan;Joshua Oppor;J. Percival;Nelli Aydinyan;A. Hauser;Elijah Ruder
威斯康星大学麦迪逊分校天文学系的Washburn天文实验室正在为11米的南部非洲大望远镜（SALT）开发一种近红外（NIR）积分场光谱仪。该仪器将把SALT的能力扩展到近红外，在0.8到1.7微米的波长范围内提供中等分辨率光谱。以前称为RSS-NIR，该光谱仪最初设计用于安装在SALT的主要焦点上，并与可见波长罗伯特斯托比光谱仪（RSS-VIS）共享一个共同的准直器和空间框架结构。然而，为了使仪器和望远镜的性能最大化，它的配置已改为光纤馈电仪器，位于望远镜下面的光谱仪室7。这一变化需要增加几个新的组件，包括一个单独的准直器；光纤整体现场单元（IFU）；一种将望远镜发出的光注入纤维的方法；还有一个冷却的外壳，用来容纳光谱仪、准直器和光纤的伪狭缝端。新的准直器由四个折射元件组成，其中一个是氟化钙，需要一个新的透镜筒和支撑结构。新的光纤系统包括一个六边形排列的217根光纤IFU和两个小束，每个小束包含15根天空光纤。IFU是由一个两部分的蛤壳不锈钢套圈制成的。现有的SALT光纤仪器馈送（FIF）机构适用于将IFU和sky束定位在sky上，而弯曲枢轴上的从运动确保光纤保持远心。一根42米长的受保护光纤电缆横跨望远镜主焦和光谱仪室的伪狭缝之间的距离。电缆由4根外径25mm的柔性导管构成。在导管内，每根纤维都被单独保护在自己的聚四氟乙烯管中。光缆通过望远镜的路线需要仔细调节弯曲的控制。所述伪狭缝包括附在狭缝板上的一排迷你v型槽块。狭缝、准直器和光谱仪被安置在SALT光谱仪室的一个40度冷的外壳内。冷却系统，开发由诺莱克科学我们的规格，仔细控制热冲击和湿度。本文介绍了重新配置的光谱仪系统的设计、集成和实验室验证，以及我们在-40环境压力环境下的操作经验。
Washburn Astronomical Laboratories in the University of Wisconsin-Madison Astronomy Department is developing a near infrared (NIR) integral field spectrograph for the 11-meter Southern African Large Telescope (SALT). This instrument will extend SALT’s capabilities into the NIR, providing medium resolution spectroscopy over the wavelength range of 0.8 to 1.7 microns. Formerly known as RSS-NIR, this spectrograph was originally designed to mount at the prime focus of SALT and share a common collimator and spaceframe structure with the visible wavelength Robert Stobie Spectrograph (RSS-VIS). However, to maximize performance of both the instrument and telescope, its configuration has been changed into a fiber fed instrument located in the spectrometer room below the telescope7. This change necessitated the addition of several new components, including a separate collimator; a fiber integral field unit (IFU); a means to inject light from the telescope into the fibers; and a cooled enclosure to house the spectrograph, collimator, and pseudo-slit end of the fiber cable. The new collimator consists of four refractive elements, one of which is calcium fluoride, and requires a new lens barrel and support structure. The new fiber system incorporates a hexagonally arranged 217-fiber IFU and two mini-bundles containing 15 sky fibers each. The IFU is fabricated out of a two-part clam-shell stainless steel ferrule. The existing SALT fiber instrument feed (FIF) mechanism is adapted to position the IFU and sky bundles on sky, while a slave motion on flexure pivots ensures that the fibers remain telecentric. A 42-m protected fiber cable spans the distance between the telescope prime focus and the pseudo-slit in the spectrometer room. The cable is constructed out of four 25mm outer diameter flexible conduits. Within the conduit, each fiber is individually protected in its own Teflon tube. The route of the fiber cable through the telescope requires careful accommodation of controlled bending. The pseudo-slit comprises a line of mini v-groove blocks attached to the slit plate. The slit, collimator, and spectrograph are housed inside a 40 cold enclosure in the SALT spectrometer room. The cooling system, developed by Norlake Scientific to our specifications, carefully controls against thermal shock and humidity. This paper describes the design, integration, and laboratory verification of the reconfigured spectrograph system, as well as our experiences operating in a -40 ambient pressure environment.