TRISPEC: A Simultaneous Optical and Near-Infrared Imager, Spectrograph, and Polarimeter

We present the design, construction, and performance of TRISPEC (Triple Range Imager and Spectrograph), a simultaneous optical and near-infrared imager, spectrograph, and polarimeter. This instrument splits the incoming light from a telescope into the three beams—one optical channel (0.45-0.90 μm) and two infrared channels (0.90-1.85 and 1.85-2.5 μm)—by means of two dichroic mirrors. It is capable of simultaneous three-band imaging or spectroscopy, with or without polarimetry. Low-resolution grisms (R ~ 70-360) cover a wide wavelength range of 0.46-2.5 μm, simultaneously. The instrument employs three arrays—one 512 × 512 SITe CCD and two 256 × 256 SBRC InSb arrays—to cover the three channels. It has been commissioned in the imaging, spectroscopic, and polarimetric modes on the United Kingdom Infrared Telescope, the University of Hawaii 2.2 m telescope, and the Okayama Astrophysical Observatory 1.88 m telescope since 1999 June.