Design and status of an optical and near-infrared spectrometer for the IRSF 1.4m Telescope

We present our new optical and near-infrared (NIR) spectrometer for the IRSF 1.4m telescope. The concept of it is an effective use of photons, and so we have designed it to obtain a spectrum of the 0.4-2.5μm range simultaneously and have a small number of optical surfaces in order to reduce reflection loss. Light collected by the telescope is separated into optical (0.45-0.90μm) and NIR (1.0-2.5μm) wavelengths by a dichroic entrance window, and two spectrometers are prepared, one for the optical wavelengths and another for the NIR. We use a sapphire prism in the NIR spectrometer, and a diffraction grating in the optical spectrometer. The optical design is very simple and the number of optical surfaces is 9 for optical and 10 for NIR (not including the telescope mirrors). A 1024×250 pixels CCD (optical) and a 1024×1024 HgCdTe detector array (NIR) are used. The spectral resolution will be 470@0.70μm and 380@1.8μm with a 1” slit width. A NIR slit viewer with a 3’.5 × 3’.5 field of view is also mounted. The development of the spectrometer will be complete by March 2013.