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Development of a slicer integral field unit for the existing optical imaging spectrograph FOCAS

2012; SPIE; Volume: 8450; Linguagem: Inglês

10.1117/12.924959

1996-756X

Shinobu Ozaki, Yôko Tanaka, Takashi Hattori, Kenji Mitsui, Mitsuhiro Fukusima, Norio Okada, Yoshiyuki Obuchi, Satoshi Miyazaki, Takuya Yamashita,

Environmental Monitoring and Data Management

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.