We have developed an optical and near-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed
camera) with imaging, spectroscopy, and polarimetry capabilities in two (one optical and one near-infrared)
bands simultaneously. Imaging capability with a field of view of 10 arcmin by 10 arcmin has been available
since 2011, as reported in the previous SPIE conference. In addition, spectroscopic and polarimetric optical
components (grisms, an Wollaston prism, a half-wave plate, and focal masks) were installed in the instrument,
which enabled us to perform spectroscopy and linear polarization measurement by imaging polarimetry and
spectro-polarimetry. Spectral resolution of R = λ/(triangle)λ ~ 440 - 800 is achieved in spectroscopy using a slit
mask with an 1".3 width. In polarimetry, instrumental polarization is less than ~0.05 % with stability of
better than ~0.05 %, which is sufficiently small to achieve an aimed accuracy of polarization measurement
of ~0.1 % at primal observing wavelengths.
We developed a new readout system for the near-infrared detector VIRGO-2K (2kx2k HgCdTe array) installed in the optical-infrared simultaneous camera, HONIR, for the 1.5 m Kanata telescope at Higashi-Hiroshima observatory. The main goal of this development is to read out one frame within ~ 1 second through 16 output readout mode of the detector, in order to reduce the overhead time per exposure. The system is based on a CCD controller, Kiso Array Controller (KAC). We redesigned the analog part of KAC to ﬁt VIRGO-2K. We employed a fully diﬀerential input circuit and a third order Bessel low-pass ﬁlter for noise reduction and a constant current system to improve the linearity of the detector. We set the cutoﬀ frequency of the Bessel low-pass ﬁlter at the readout clock rate (120 kHz). We also set the constant current at 200 μA according to the data sheet of VIRGO-2K. We tested the new readout system at room temperature and conﬁrmed that the low-pass ﬁlter works well as designed. The ﬂuctuation of the current level of the constant current system is less than 2% for the typical output voltage range of VIRGO-2K (3.2-4.4 V). We measured the readout noise caused by the new readout system (connected to cooled multiplexer) and found that it is 30-40 μV rms, being comparable to or slightly higher than the typical readout noise of VIRGO-2K, ∼ 37 μV rms.
We have developed an optical-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed camera) to be attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Hiroshima University. HONIR is a three color (one optical and two near-infrared bands among 0.5–2.4 µm) simultaneous imager and spectrograph with a polarimetry function. The field of view of the imaging mode is 10 arcmin square with a spatial sampling of 0".29. Among the planned multipurpose functions, a two color (0.5–1.0 µm and 1.15–2.40 µm) simultaneous imaging function has been installed and operated so far. The remaining functions, spectroscopy and polarimetry, and the second near-infrared band arm, are under development and will be installed in the near future.