Affiliation: ENGINEER
Conference ID : ASI2022_745
Title : DMD based Multi Object Spectrograph for Indian Spectroscopic and Imaging Space Telescope (INSIST
Authors : Vineeth Valsan, Subramaniam A, Maheswar.G, Totan Chand, Vishnu Unni C, Akhil Jaini
Abstract Type: Poster
Abstract Category : Instrumentation and Techniques
Abstract : Digital micromirror device (DMD) based Multi-Object slit Spectrograph (MOS) is one of the innovative focal plane instruments for the proposed a meter class future space UV mission, the Indian Spectroscopic Imaging Space Telescope(INSIST). DMD is comprised of an array of individually addressable reflective elements called micromirrors. During operation, the micromirrors are tilted between two stable states, typically at + and - 12 degrees from the device normal. In a MOS, the DMD is located at the focal plane of the telescope. The micromirrors act as slits, either reflecting light towards or away from the spectrograph. INSIST optics delivers an f/20.6 beam to the focal plane with a very narrow telecentric angle. DMD with an array of 1920x980 micromirrors covers a sky of 217”x117” is placed at the focal plane. Two spectrograph configurations have been explored for multi-object capability, one with convex grating and the other with plane reflection grating. Gratings in both designs are blazed to center wavelength (200nm) at first order for optimal efficiency. The spectrographs cover wavelength range of 150nm-300nm and deliver R~2000 at the mean wavelength. Spatial sampling of the spectra at the detector plane is ~ 3pixels which is equivalent to 0.3arcsec. The extend of the spectra covers ~4500 pixels. The longest single slit the DMD can provide is ~ 2.54arcmin and the multiplexing of the spectrograph is ~200. The format of the detector required for covering the maximum multiplexing is ~ 7200x2300pixels. We present the details of the spectrograph configured for INSIST.