Optical architecture of mid-infrared instruments (MIRACLE/MIRMES/MIRHES) on board SPICA

Abstract

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy, envisioned for launch in 2018. Mid-infrared instruments for SPICA are required to have three basic capabilities; a wide-field imaging, spectroscopic capability, and coronagraphic capability as an option. First two capabilities are implemented by three instruments; MIRACLE(Mid-infRAred Camera w/o Lens), MIRMES(Mid-IR Medium-resolution Echelle Spectrometer), and MIRHES(Mid-IR High-resolution Echelle Spectrometer). Here, we present an optical architecture of the union of MIRACLE, MIRMES, and MIRHES. MIRACLE has two channels (-S for short wavelength and -L for long wavelength) to cover the wavelength range 5 to 40 micron. MIRACLE-L and MIRMES are packaged into one unit with common optical bench and MIRACLE-S and MIRHES are packaged into another unit. Two units are independent with each other and occupy different field of view of the SPICA telescope. Each unit has common fore-optics shared by MIRACLE and MIR(M/H)ES. This fore-optics is designed using reflective mirror optics only, and has wide filed of view(FOV). Most of the FOV is used by MIRACLE and small part of the FOV is used by MIRMES or MIRHES. This structure of the instruments reduces the size and weight of the instruments. This benefit outweigh the complexity of the instruments.