：The infrared spectra of the Sun include numerous absorption lines, among which He I 10830 Å is one of the most representative spectral lines in the near-infrared band formed in the high-temperature region of the upper chromosphere. The observation of the spectral lines is important for the solar physics research. In this paper, the monochromatic images of sunspots in the He I 10830 Å spectral line was obtained by the one-meter new vacuum solar telescope at the Fuxian Lake solar observation base. The infrared detector using the domestic InGaAs 640×512 focal plane array device can reach a low dark current of 62e -/s/pixel and readout noise of 25.4 eat 78K by Stirling cooler. The laboratory tests and actual astronomical observations were completed. In the case of large detector readout noise and dark current, a method of extracting the observation target by effectively calculating the flat field was proposed. A monochromatic image of sunspots with He I 10830 Å is obtained for the first time in China using the self-developed detector.

Polarization information is widely used in complex applications such as industrial detection, biomedicine, earth remote sensing, modern military, and aerospace. However, traditional polarization devices cannot adequately satisfy the requirements of increasingly complex environments. A subwavelength grating consisting of three types of materials, namely, aurum, platinum, and titanium, was designed to improve the performance of the polarimetric components of a midwavelength infrared polarization imaging system. The morphological structure parameters of the designed grating were optimized by analyzing the effects on the polarization performance through the rigorous coupled wave theory. The proposed Au-Pt-Ti composite grating could address the problem of grating peeling off from the substrate because of high temperature during preparation. The composite grating has some advantages such as high mechanical stability, lower oxidation, and great polarization properties. The diffraction can be reduced and the extinction ratio (ER) can be effectively enhanced in a midwave infrared (MWIR) focal plane array through appropriate reduction in the termination edge spacing and the addition of a gold frame between polarizer pixels. The grating with a period of 0.8 μm was designed for application in the MWIR band. The fill factor was 0.5 and the depths of Au-Pt-Ti in the grating region were 0.44 μm. Each pixel was separated by a 3.2-μm wide gold frame. Modeling results revealed that the ER of grating was higher than 28.68 and 32.77 above the incident wavelengths of 3.89 and 4.57 μm, respectively. Additionally, excellent polarization capability was observed over a wide MWIR spectrum. Furthermore, the current manufacturing process level may generate polarizers with the aforementioned structural specifications.