Ultra-Wide-Field Long-Wave Infrared System via Hybrid Refractive–Reflective Structure and Field of View Stitching

To address the application demands of ultra-wide-field optical systems, we developed a compact, long-infrared waveband optical system using a field-of-view (FoV) stitching method. This system features a refractive–reflective hybrid structure, with the reflective pathway expanding the FoV and the refractive pathway employing germanium to correct field defects and aberrations. By stitching the FoVs of the two structures, we achieved an ultra-wide-field long-infrared-waveband imaging system over a range of 0°~190°, with an operational wavelength range of 8.7~11.5 μm. The system exhibits excellent imaging performance, with a modulation transfer function (MTF) exceeding 0.5 at 17 lp/mm, the blur spot remaining within the airy disk limit, and the energy concentration exceeding 60% at 15 μm: the tolerance design meets the imaging requirements. Additionally, the system maintains stable image quality within the temperature range of −20 °C~60 °C. The design offers excellent imaging quality, high design flexibility, good real-time performance, compact size, and low economic cost, providing an effective optical structure and realization strategy for ultra-wide-field imaging systems.