Development of a large-aperture wide-angle reflector for triple-band infrared applications

Multi-band infrared detectors can simultaneously capture radiation information across multiple wavelengths, offering significant advantages over single-band infrared detectors in target recognition, classification, temperature measurement, and information extraction. Consequently, they have become a central focus of infrared detector technology research. As a key optical component of multi-band infrared detectors, the performance of the three-band large-aperture wide-angle infrared mirror directly determines detection accuracy. In the design phase, this study selected three materials: Ge, ZnS, and YbF₃, based on high-reflectivity coating design principles, and optimized a structurally robust infrared reflector coating system through spectral superposition combined with TFCalc software. During the preparation stage, ion-source-assisted deposition was employed, and the issue of film delamination was resolved by optimizing the deposition process. During spectral testing, problems related to spectral drift in the samples were addressed through film thickness error experiments and optimization of the YbF₃ process. Test results indicate that, at an incident angle of 45°, the infrared mirror achieves an average reflectance of 96.93% in the 3−5 µm spectral band, 96.54% in the 8−12 µm spectral band, and 94.64% in the 1.064 µm spectral band, the spectral non-uniformity within the 270 mm×270 mm aperture for the 3−5 µm and 8−12 µm spectral bands is 4.83%. In accordance with the national standard GJB 2485A-2019 (Environmental Test Standard), the prepared samples successfully passed adhesion and high and low temperature tests, meeting the application requirements for multi-band infrared detectors.