HDR optical–algorithm co-design of space-based asteroid detection systems based on background radiation priors

For mid-infrared (3-5 μm) asteroid detection scenarios characterized by weak targets and strong background radiation, this study addresses the dynamic range mismatch caused by zodiacal background emission and proposes a high-dynamic-range detection approach based on a digital micromirror device (DMD). The DIRBE-model-based prediction of zodiacal radiation is first used as a prior. Then, an on-orbit observation residual equation is constructed to correct the background parameters. The directional radiance field is mapped into a two-dimensional intensity matrix, from which pixel-level duty-cycle weights are derived and decomposed into binary mask images to drive the DMD, thereby achieving pixel-level exposure-time modulation. This method effectively avoids the issue in conventional dimming schemes where stellar targets are simultaneously modulated. To verify its feasibility and engineering value, both simulation analysis and a proof-of-concept experiment were conducted. The results show that the aperture-photometry signal-to-noise ratios of multiple stars improved from undetectable to detectable levels, with enhanced contrast and overall target visibility. In summary, the proposed method achieves on-orbit suppression of strong zodiacal background radiation and pixel-level dynamic range extension, providing a feasible system solution and practical reference for next-generation asteroid detection payloads.