PROCEEDINGS ARTICLE | September 13, 2012
Proc. SPIE. 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
KEYWORDS: Telescopes, Mirrors, Spectrographs, Glasses, Reflectivity, Vignetting, Spherical lenses, Off axis mirrors, Prototyping, Surface finishing
We are developing an integral field unit (IFU) with an image slicer for the existing optical imaging spectrograph,
Faint Object Camera And Spectrograph (FOCAS), on the Subaru Telescope. Basic optical design has already
finished. The slice width is 0.4 arcsec, slice number is 24, and field of view is 13.5x 9.6 arcsec. Sky spectra
separated by about 3 arcmin from an object field can be simultaneously obtained, which allows us precise
background subtraction. The IFU will be installed as a mask plate and set by the mask exchanger mechanism
of FOCAS. Slice mirrors, pupil mirrors and slit mirrors are all made of glass, and their mirror surfaces are
fabricated by polishing. Multilayer dielectric reflective coating with high reflectivity (< 98%) is made on each
mirror surface. Slicer IFU consists of many mirrors which need to be arraigned with high accuracy. For such
alignment, we will make alignment jigs and mirror holders made with high accuracy. Some pupil mirrors need
off-axis ellipsoidal surfaces to reduce aberration. We are conducting some prototyping works including slice
mirrors, an off-axis ellipsoidal surface, alignment jigs and a mirror support. In this paper, we will introduce our
project and show those prototyping works.
