Compact Infrared Imaging System Based on Small-Diameter Chalcogenide Glass Fiber Bundles

Infrared coherent fiber bundles are increasingly employed in imaging systems that demand compact, high-performance designs, particularly in constrained or challenging environments. This paper presents a compact thermal imaging system based on infrared coherent fiber bundles, capable of high-resolution temperature measurement and thermal imaging in confined spaces. The system employs classic chalcogenide glasses (As₄₀S₆₀ and As₃₈S₆₂) for the core and cladding materials, utilizing the stack-and-draw technique to create tightly aligned fiber bundles, thereby ensuring high light energy acceptance and uniform pixel spacing. An amplified telecentric lens was designed for the 3–5 μm mid-infrared range, optimizing image quality while minimizing distortion. To evaluate the performance of the imaging system, several experiments were conducted, including transmission uniformity testing of the coherent fiber bundles, light energy utilization, spatial resolution, temperature resolution, and crosstalk measurements. The results show that the fabricated chalcogenide fiber bundles exhibit low crosstalk (less than 1%) and smaller temperature resolution discrimination (0.72 K), alongside superior optical quality. Finally, the system was employed to image both temperature gradient and constant-temperature objects, demonstrating excellent fiber bundles stability during imaging and superior temperature resolution.