Designing the optimal semi-warm NIR spectrograph for SALT via detailed thermal analysis
Designing the optimal semi-warm NIR spectrograph for SALT via detailed thermal analysis
复制标题
通过详细的热分析设计最佳的 SALT 半温近红外光谱仪
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
A. R. Rogers
中科院分区：
文献类型：
--
作者：
M. Wolf;A. Sheinis;M. Mulligan;Jeffrey P. Wong;A. R. Rogers
南非大型望远镜 (SALT) 上的罗伯特·斯托比摄谱仪 (RSS) 的近红外 (NIR) 升级，RSS/NIR，扩展了光学摄谱仪所有模式的光谱覆盖范围。 RSS/NIR 是一款中低分辨率光谱仪，具有宽带、分光偏振和法布里-珀罗成像功能。光学臂和近红外臂可同时使用，将光谱覆盖范围从 3200 Å 扩展到约 1.6 μm。两条手臂通过铰接光栅和相机利用高效体相位全息光栅。 NIR 相机采用了采用 Epps 光学设计的 HAWAII-2RG 探测器，该设计由 6 个球形元件组成，并在所有波长和视场角下提供 7.5 ± 1.0 μm 的亚像素 rms 图像尺寸。近红外光谱仪是半温光谱仪，与光学臂共用一个狭缝平面和部分准直器。预杜瓦瓶冷却至环境温度以下，容纳最终的近红外准直器光学器件、光栅/法布里-珀罗标准具、偏振分束器和前三个相机光学器件。最后三个摄像头元件、滤光片和探测器安装在低温冷却的杜瓦瓶中。半温设计概念长期以来一直被提出作为将光学仪器扩展到近红外区域的经济方法，但成功率非常有限。我们设计工作的主要部分需要使用非顺序光线追踪进行详细的热分析，以交互方式指导机械设计，并确定真正可实现的长波长截止，在该截止范围内天文观测将受到天空限制。在本文中，我们描述了我们的热分析、分级冷却方案的设计概念以及要纳入整体机械设计和挡板的结果。
The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the optical spectrograph. The RSS/NIR is a low to medium resolution spectrograph with broadband, spectropolarimetric, and Fabry-Perot imaging capabilities. The optical and NIR arms can be used simultaneously to extend spectral coverage from 3200 Å to approximately 1.6 μm. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera incorporates a HAWAII-2RG detector with an Epps optical design consisting of 6 spherical elements and providing subpixel rms image sizes of 7.5 ± 1.0 μm over all wavelengths and field angles. The NIR spectrograph is semi-warm, sharing a common slit plane and partial collimator with the optical arm. A pre-dewar, cooled to below ambient temperature, houses the final NIR collimator optic, the grating/Fabry-Perot etalon, the polarizing beam splitter, and the first three camera optics. The last three camera elements, blocking filters, and detector are housed in a cryogenically cooled dewar. The semi-warm design concept has long been proposed as an economical way to extend optical instruments into the NIR, however, success has been very limited. A major portion of our design effort entails a detailed thermal analysis using non-sequential ray tracing to interactively guide the mechanical design and determine a truly realizable long wavelength cutoff over which astronomical observations will be sky-limited. In this paper we describe our thermal analysis, design concepts for the staged cooling scheme, and results to be incorporated into the overall mechanical design and baffling.