Design and early performance of IGRINS (Immersion Grating Infrared Spectrometer)

Abstract

The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser is a silicon immersion grating. IGRINS covers the entire portion of the wavelength range between 1.45 and 2.45μm that is accessible from the ground and does so in a single exposure with a resolving power of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is 1ʺ x 15ʺ and the plate scale is 0.27ʺ pixel -1 . The spectrograph employs two 2048 x 2048 pixel Teledyne Scientific & Imaging HAWAII-2RG detectors with SIDECAR ASIC cryogenic controllers. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be only 25mm, which permits a moderately sized (0.96m x 0.6m x 0.38m) rectangular cryostat to contain the entire spectrograph. The fabrication and assembly of the optical and mechanical components were completed in 2013. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present early performance test results obtained from the commissioning runs at the McDonald Observatory.

LHS 1610A: A Nearby Mid-M Dwarf with a Companion That Is Likely a Brown Dwarf

“…IGRINS is a cross-dispersed, high-resolution (R=λ/Δλ= 45,000) near-infrared spectrograph with a wavelength coverage of 1.45 to 2.5 μm, which obtains simultaneous observations in both the H and K bands (Yuk et al 2010;Park et al 2014;Mace et al 2016aMace et al , 2016b. We calculated exposure times to achieve an S/N of approximately 150 per wavelength bin.…”

Exposure time calculator for Immersion Grating Infrared Spectrograph: IGRINS

“…This instrument has been employed on the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory since 2014 March. Detailed descriptions of IGRINS can be found in Yuk, Jaffe & Barnes et al (2010) and Park, Jaffe & Yuk et al (2014).…”

Capturing complete spatial context in satellite observations of greenhouse gases

“…CARBO exploits immersion gratings to break the size-resolving power constraints of traditional spectrometer designs [35]. An immersion grating is a diffractive device where the light is incident on the grating from inside a dielectric medium [36].…”