The design and construction of the fiber instrument feed for the SALT NIR integral field spectrograph
Abstract
The near infrared spectrograph for the Southern African Large Telescope has been developed at the University of Wisconsin. This spectrograph (see Wolf et al., these proceeding) is fiber-IFU fed, and the instrument placed in a -40C freezer in the spectrograph room at SALT. The rectangular 212 fiber object IFU and 38 fiber sky mini-IFU are placed in the fiber instrument feed (FIF) in the SALT payload. The IFUs patrol the telescope field and the separation between them can be adjusted. When the separation changes the bundles automatically tilt to maintain telecentricity. The 43m fibers are individually sheathed in Teflon tubes and placed in one of 4 rugged conduits which feed through the telescope payload, down the telescope truss, through the telescope pintle bearing and into the cooled Spectrograph room. Just outside of the instrument enclosure (freezer) the fibers split out of the conduit via break-out boxes into one of four strain relief boxes in which the fibers are individually layered in take-up loops and then fed through a rubber seal system in the freezer wall. Inside the freezer the fibers route down to the spectrograph slit where they are arrayed in one of 8 v-groove blocks which are individually adjustable in dovetail slots on the slit plate. In this paper we detail the design of the FIF, discuss the design and complex fabrication of the fiber cable; we also discuss the design of the breakout boxes, strain relief box and cold feedthrough. Finally, we will discuss the design and alignment of the fiber slit.
- Publication:
-
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation
- Pub Date:
- August 2022
- DOI:
- 10.1117/12.2630399
- Bibcode:
- 2022SPIE12188E..5NS