Fabry–Pérot Interferometer-Based Tunable Narrow-Band Imager for Solar Chromospheric Observation: First Results

Recently, we have developed a tunable narrow-band imager (NBI) with high spectral resolution based on a Fabry–Pérot (FP) interferometer to observe the solar chromosphere. The NBI system is designed for imaging the Sun at the H α wavelength (6563 Å). The FP interferometer has a bandpass (FWHM) of 0.09 Å and a free spectral range (FSR) of 3.85 Å at λ = 628 nm, working in combination with a prefilter with a bandpass of 1.6 Å and a center wavelength at 656.3 nm to achieve narrow-band imaging. We have successfully tested the NBI system on the 65-cm Educational Adaptive-optics Solar Telescope (EAST) in the Shanghai Astronomy Museum, and observed the sunspots in active region (AR) 12880 of the Sun on October 2 and 3, 2021. In this paper, we briefly present a description of the instrument, experimental observations, data processing, and the first observational results.