A Study on Differential Detection Technology for Long-Range Explosive Flash Events

Infrared transient photodetectors used for long-range explosive flash detection are often limited by rapid signal attenuation and strong background infrared noise, which degrade signal-to-noise ratio and trigger reliability. This work proposes a coplanar binocular differential infrared transient trigger that maintains microsecond-scale response while substantially extending detection range. A coupled radiation–electronic model is established, from which a limit-detection-distance model based on noise-equivalent power is derived and generalized to the binocular differential architecture to quantify range gain. A hardware prototype with matched dual-lens photodiode channels, a high common-mode rejection ratio differential front end, Sallen–Key band-pass filtering, and threshold triggering achieves simultaneous signal amplification and common-mode/high-frequency noise suppression. Experiments show model–measurement deviation below 0.5% and a 2.8× increase in maximum detection distance over a monocular system; field tests confirm reliable triggering of explosive infrared flashes at 3.2 km with trigger delay < 10 μs, demonstrating a compact and quantitatively designable solution for high-sensitivity, long-range explosive flash sensing.