A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry

Polarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar filaments, which occasionally erupt and develop into interplanetary flux ropes, is of particular interest. To measure the magnetic field in filaments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has $2048\times 2048$ pixels, focusing on the wavelengths in the range of $1.0-1.6\mu \text{m}$. We solved the problem of the difficult operation of the H2RGs under "fast readout mode" synchronizing with high-speed polarization modulation by introducing a "MACIE" (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific. This enables polarization measurements with high frame-rates, such as 29–117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.