Researchers have developed a compact and lightweight single-photon airborne lidar system that can capture high-resolution 3D images using low-power laser technology. This advancement could make single-photon lidar practical for applications such as environmental monitoring, 3D terrain mapping, and object identification in air and space settings. Single-photon lidar utilizes single-photon detection techniques to measure the time it takes laser pulses to reach objects and return. It is particularly useful for airborne applications as it enables precise 3D mapping of terrain and objects even in challenging environments like dense vegetation or urban areas.
The research team, led by Feihu Xu from the University of Science and Technology of China, emphasizes the need to shrink the entire system and reduce its energy consumption for use on resource-limited drones or satellites. By incorporating recent technological developments, the team was able to create a system with the lowest laser power and smallest optical aperture compared to other state-of-the-art airborne lidar systems while maintaining good performance in detection range and imaging resolution. Published in Optica, the researchers demonstrate the system’s ability to achieve imaging resolution surpassing the diffraction limit of light through sub-pixel scanning and a new 3D deconvolution algorithm, capturing high-resolution 3D images during daytime over large areas aboard a small plane.
Xu highlights the system’s potential to enhance our understanding of the world and contribute to a more sustainable and informed future. For instance, the system deployed on drones or small satellites could monitor changes in forest landscapes, assess deforestation impacts, or generate 3D terrain maps post-earthquake to guide rescue teams efficiently. The system works by sending light pulses from a laser towards the ground, where they bounce off objects and are detected by sensitive single-photon avalanche diode (SPAD) arrays. These detectors efficiently capture the reflected laser pulses, enabling the use of a lower-power laser. To reduce system size, the researchers utilized small telescopes with a 47 mm optical aperture as receiving optics.
The system calculates the time-of-flight of returned single photons to determine the distance light traveled to the ground and back, reconstructing detailed 3D terrain images using computational imaging algorithms. Special scanning mirrors perform continuous fine scanning, capturing sub-pixel information of ground targets, while a new photon-efficient computational algorithm extracts this information from a small number of raw photon detections to reconstruct super-resolution 3D images despite weak signals and strong solar noise. Ground tests confirmed the system’s effectiveness, achieving lidar imaging resolution of 15 cm from 1.5 km away with default settings, improving to 6 cm resolution with sub-pixel scanning and 3D deconvolution.
Further validation was conducted through daytime experiments aboard a small airplane over several weeks in Yiwu City, China, revealing detailed features of landforms and objects, verifying the system’s functionality and reliability in real-world scenarios. The team is focused on enhancing system performance and integration, with the long-term goal of deploying it on a spaceborne platform like a small satellite. Improvements in stability, durability, and cost-effectiveness are crucial before commercialization. In summary, the development of a compact and lightweight single-photon airborne lidar system holds significant promise for advancing environmental monitoring, 3D terrain mapping, and object identification in air and space applications.
