The near infrared camera for the Subaru Prime Focus Spectrograph
The near infrared camera for the Subaru Prime Focus Spectrograph
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用于斯巴鲁 Prime Focus 光谱仪的近红外相机
DOI：
10.1117/12.2057136
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Shimono
中科院分区：
文献类型：
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作者：
S. Smee;J. Gunn;M. Golebiowski;R. Barkhouser;S. Vives;S. Pascal;M. Carr;S. Hope;C. Loomis;M. Hart;H. Sugai;N. Tamura;A. Shimono
介绍了正在为斯巴鲁望远镜研制的SuMIRe(斯巴鲁图像和红移测量)主聚焦光谱仪(PFS)的近红外相机的详细设计。PFS光谱仪旨在同时收集2394个天体的光谱，覆盖的波长从380 nm-1.26μm。该光谱仪由四个相同的光谱仪模块组成，每个模块从望远镜主焦点的机器人光纤定位器收集大约600个光谱。每个光谱仪模块将有两个波长范围为380 nm-640 nm和640 nm-955 nm的可见通道，以及一个波长范围为955 nm-1.26μm的近红外(NIR)通道。每个通道中的散射光由300 mm焦距f/1.07真空施密特相机成像到4k x 4k，15微米像素，探测器格式。对于近红外通道，使用了去除HgCdTe衬底的Teledyne1.7μm截止器件。在可见通道中，使用滨松的ccd。这些相机体积很大，入射窗口的清晰光圈为300毫米，质量约为250公斤。像两个可见通道相机一样，近红外相机只有四个光学元件：一个两元折射校正器，一个曼金镜和一个平场透镜。考虑到宽视场和波长范围，这种简单的设计产生了非常好的成像性能，这在很大程度上要归功于施密特主镜使用了曼金镜(具有反射后表面的透镜)。在近红外相机的情况下，后反射面是二色性的，它反射带内波长并传输超过1.26μm的波长。这与第二个校正器元件背面的热抑制滤光片相结合，极大地减少了到达探测器的带外热辐射。相机的光学元件和探测器被封装在一个低温恒温器中，并由两个斯特林循环制冷器进行冷却。第一个校正器元件用作真空窗口，而第二个元件是隔热的，并且是冷漂浮的。主要由碳化硅构成的组件用于安装曼金镜，并支撑探测器和场平坦器。冷光学元件和热环境之间的隔热由G10支架、多层绝缘材料和低温恒温器内的真空空间提供。在本文中，我们描述了PFS近红外相机的详细设计，并讨论了其预测的光学、热和机械性能。
We present the detailed design of the near infrared camera for the SuMIRe (Subaru Measurement of Images and Redshifts) Prime Focus Spectrograph (PFS) being developed for the Subaru Telescope. The PFS spectrograph is designed to collect spectra from 2394 objects simultaneously, covering wavelengths that extend from 380 nm - 1.26 μm. The spectrograph is comprised of four identical spectrograph modules, with each module collecting roughly 600 spectra from a robotic fiber positioner at the telescope prime focus. Each spectrograph module will have two visible channels covering wavelength ranges 380 nm - 640 nm and 640 nm - 955 nm, and one near infrared (NIR) channel with a wavelength range 955 nm - 1.26 μm. Dispersed light in each channel is imaged by a 300 mm focal length, f/1.07, vacuum Schmidt camera onto a 4k x 4k, 15 µm pixel, detector format. For the NIR channel a HgCdTe substrate-removed Teledyne 1.7 μm cutoff device is used. In the visible channels, CCDs from Hamamatsu are used. These cameras are large, having a clear aperture of 300 mm at the entrance window, and a mass of ~ 250 kg. Like the two visible channel cameras, the NIR camera contains just four optical elements: a two-element refractive corrector, a Mangin mirror, and a field flattening lens. This simple design produces very good imaging performance considering the wide field and wavelength range, and it does so in large part due to the use of a Mangin mirror (a lens with a reflecting rear surface) for the Schmidt primary. In the case of the NIR camera, the rear reflecting surface is a dichroic, which reflects in-band wavelengths and transmits wavelengths beyond 1.26 μm. This, combined with a thermal rejection filter coating on the rear surface of the second corrector element, greatly reduces the out-of-band thermal radiation that reaches the detector. The camera optics and detector are packaged in a cryostat and cooled by two Stirling cycle cryocoolers. The first corrector element serves as the vacuum window, while the second element is thermally isolated and floats cold. An assembly constructed primarily of silicon carbide is used to mount the Mangin mirror, and to support the detector and field flattener. Thermal isolation between the cold optics and warm ambient surroundings is provided by G10 supports, multi-layer insulation, and the vacuum space within the cryostat. In this paper we describe the detailed design of the PFS NIR camera and discuss its predicted optical, thermal, and mechanical performance.