Preliminary design of IGRINS (Immersion GRating INfrared Spectrograph) In-Soo Yuk* a , Daniel T. Jaffe b , Stuart Barnes c , Moo-Young Chun a , Chan Park a , Sungho Lee a,c , Hanshin Lee c , Weisong Wang b , Kwi-Jong Park a , Soojong Pak d , Joseph Strubhar c , Casey Deen b , Heeyoung Oh a,d , Haingja Seo d , Tae-Soo Pyo f , Won-Kee Park d,e , John Lacy b , John Goertz c , Jared Rand b , Michael Gully-Santiago b a Korea Astronomy and Space Science Institute, 61-1 Hwaam-dong, Daejeon 305-348, South Korea; b Dept. of Astronomy, Univ. of Texas at Austin, 1 University Station, Austin, TX 78712, USA; c McDonald Observatory, Univ. of Texas at Austin, 1 University Station, Austin, TX 78712, USA; d School of Space Research, Kyung Hee Univ., Yongin-si, Gyeonggi-do 446-71, South Korea; e Center for the Exploration of the Origin of the Universe, Seoul National Univ., Seoul, South Korea; f Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720, USA ABSTRACT The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS. IGRINS can observe all of the H- and K-band atmospheric windows with a resolving power of 40,000 in a single exposure. The spectrograph uses a white pupil cross-dispersed layout and includes a dichroic to divide the light between separate H and K cameras, each provided with a 2kⅹ2k HgCdTe detector. A silicon immersion grating serves as the primary disperser and a pair of volume phased holographic gratings serve as cross dispersers, allowing the high resolution echelle spectrograph to be very compact. IGRINS is designed to be compatible with telescopes ranging in diameter from 2.7m (the Harlan J. Smith telescope; HJST) to 4 - 8 m telescopes. Commissioning and initial operation will be on the 2.7m telescope at McDonald Observatory from 2013. Keywords: near-infrared, spectrograph, high resolution, silicon, immersion grating 1. INSTRUMENT OVERVIEW IGRINS will be one of a new generation of sensitive high resolution spectrographs with broad instantaneous wavelength coverage. Particularly for science cases requiring broad coverage, it will open up a new way of doing high resolution IR spectroscopy. As a result, there is a significant amount of exploratory science to be done on modest-sized telescopes. IGRINS will cover all of the H (1.6 μm wavelength) and K (2.2 μm wavelength) atmospheric windows in a single exposure at a resolving power, R = 40,000 (Table 1). The instrument performance goals call for a system that will be the best in the world in this wavelength in terms of slit width-resolving power product, instantaneous wavelength coverage, and system throughput. A significant design goal is to produce an instrument with a simple opto-mechanical layout and very few moving parts to allow relatively straightforward use by a broad community of users. IGRINS uses three key components to improve the performance and to overcome the current limitations on high resolution near-IR spectrographs : (1) Silicon immersion grating, (2) HAWAII-2RG with SIDECAR ASIC, (3) a Volume Phase Holographic (VPH) grating. z Silicon Immersion Grating : The high performance immersion grating is compact and robust. The wavelength of light incident on the grating shrinks by a factor equal to the refractive index, n (3.4 for Si), when the grating is immersed in a dielectric. This means that an immersion instrument can have the same resolving power with a factor of 3.4 times smaller collimated beam diameter than an instrument with the same geometry and a Ground-based and Airborne Instrumentation for Astronomy III, edited by Ian S. McLean, Suzanne K. Ramsay, Hideki Takami, Proc. of SPIE Vol. 7735, 77351M · © 2010 SPIE · CCC code: 0277-786X/10/$18 · doi: 10.1117/12.856864 Proc. of SPIE Vol. 7735 77351M-1 Downloaded from SPIE Digital Library on 31 Aug 2010 to 163.180.171.191. Terms of Use: http://spiedl.org/terms