Development of an integral field unit for a near-infrared multi-object imaging spectrograph SWIMS

摘要

We are developing an integral field unit (IFU) for a near-infrared multi-object imaging spectrograph SWIMS(Simultaneous-color Wide-field Infrared Multi-object Spectrograph). SWIMS is an instrument for the 6.5mtelescope of the University of Tokyo Atacama Observatory (TAO) project on the summit of Co. Chajnantor(altitude of 5,640m) in northern Chile. Most of near infrared integral field spectrographs (IFSs) on 8–10m classtelescopes are used with adaptive optics and have fine spatial sampling. Compared with them, SWIMS IFUhas higher sensitivity for extended objects because it has coarser spatial sampling optimized for seeing-limitobservations. We have investigated the feasible optical design, and found a possible layout whose field of viewis about 14 x 10 arcsecsup2/sup with 0.4 arcsec slice width. All IFU mirror arrays will be made of aluminum alloy tomatch the thermal expansion with support structures, as they are placed in a cryogenic environment. They willbe fabricated monolithically with high precision machining to reduce alignment process. We have carried out afabrication test of a spherical surface and confirmed that surface roughness and surface figure error are enoughlow for near-infrared light. As a next step, fabrication of a prototype mirror array with 3 reflective surfaces isplanned. In this paper, we will show our project outline, the IFU optical design and the results of prototypingworks.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.