Ultra Compact Spaceborne Computational Single Photon 3D Imaging Based on Temporal Coding and Co-aperture Active-Passive Fusion

High-resolution, wide-swath, and all-weather 3D Earth observation is of paramount significance for Earth system science, carbon cycle monitoring, disaster response, and fine-scale topographic mapping. However, scaling traditional spaceborne LiDAR systems toward multi-beam, high-repetition-rate, and multi-modal fusion configurations is fundamentally bottlenecked by range ambiguity, intense solar background noise, and the stringent size, weight, and power (SWaP) constraints associated with separated active and passive payloads. Here, we demonstrate an ultra-compact spaceborne multi-beam single-photon LiDAR 3D imaging system (UCSMSPL) that integrates computational temporal coding with co-aperture active–passive fusion, and present its detection results acquired in-orbit. Despite stringent payload resource constraints (~0.18 m³, 117 kg, and 490 W), the system successfully demonstrated in-orbit parallel single-photon earth observation with 36 independent detection channels. Its co-aperture dichroic design provides a parallax-free, hardware-level 1:40 spatial correspondence between the 1064 nm single-photon ranging channels and a 1440-pixel visible-light CCD array. By combining computational photonic temporal coding with cross-correlation decoding, the payload further enables direct in-orbit retrieval of absolute target elevations (with a calibrated precision of 0.15 m). By synergizing optical system integration with computational photonics, this work demonstrates high-density, low-power, multi-modal 3D remote sensing on a micro-satellite platform, establishing a new paradigm for real-time, constellation-based 3D Earth observation.