Researchers have developed a compact, lightweight, single-photon airborne lidar system that uses low-power lasers to acquire high-resolution 3D images. This advance could lead to the utility of single-photon lidar in aviation and aerospace applications such as environmental monitoring, 3D topographic mapping, and object recognition.
Single-photon lidar uses single-photon detection technology to measure the time it takes for a laser pulse to reach an object and return. Single-photon lidar is particularly well suited for airborne applications because it enables high-precision 3D terrain and object mapping, even in harsh environments such as dense vegetation or urban areas.
Xu Feihu, a member of the research team from the University of Science and Technology of China, said: "Using single-photon lidar technology on a drone or satellite with limited resources requires scaling down the entire system and reducing energy consumption. We were able to incorporate the latest technological developments into the system, which uses the lowest laser power and smallest optical aperture compared to other state-of-the-art airborne LiDAR systems, while still maintaining good performance in terms of detection range and imaging resolution. ”
In the journal Optica, the researchers demonstrated that the system is capable of achieving imaging resolution beyond the diffraction limit of light when using subpixel scanning and a novel 3D deconvolution algorithm. They also demonstrated the system's ability to capture large, high-resolution 3D images over a large area using a small aircraft during the day.
"Ultimately, our work has the potential to enhance our understanding of the world around us and help create a more sustainable and informed future for all," Xu said. For example, our systems can be deployed on drones or small satellites to monitor changes in forest landscapes, such as deforestation or other impacts on forest health. It can also be used to generate 3D topographic maps after an earthquake to help assess the extent of damage and provide guidance to rescue teams, saving lives. ”
The researchers demonstrated the system's capabilities in the real world by using the system in a small aircraft to capture high-resolution 3D images of a large area during the day.
Scaled-down single-photon lidar
The new airborne single-photon lidar system works by sending light pulses from a laser to the ground. These pulses bounce off the object and are then captured by a very sensitive detector known as a single-photon avalanche diode (SPAD) array. These detectors have increased sensitivity to single photons and are able to detect reflected laser pulses more efficiently, allowing the use of lower power lasers. To reduce the size of the entire system, the researchers used a small telescope with an optical aperture of 47 mm as the receiving optics.
By measuring the flight time of the returned single photon, it is possible to calculate the time it takes for the light to reach the ground and return. Computational imaging algorithms can then be used to reconstruct detailed 3D images of the terrain from this information.
"A key part of the new system is a special scanning mirror that can perform continuous, detailed scans to capture sub-pixel information of ground targets," Xu said. In addition, a new photon-efficient computational algorithm can extract this subpixel information from a small number of raw photon detections, which can overcome the challenges posed by weak signals and strong solar noise and reconstruct super-resolution 3D images. ”
Ground and air tests
The researchers conducted a series of tests to verify the capabilities of the new system. Pre-flight ground tests confirmed the effectiveness of the technology and showed that the system is capable of lidar imaging from 1.5 km away with a resolution of 15 cm at default settings. Once subpixel scanning and 3D deconvolution techniques were employed, the researchers were able to display an effective resolution of 6 centimeters at the same distance.
The researchers also conducted a multi-week daytime experiment using the system on a small aircraft in Yiwu, Zhejiang Province, China. These experiments successfully revealed the detailed features of various landforms and objects, confirming the functionality and reliability of the system in real-world scenarios.
The research team is currently working to improve the performance and integration of the system, with the long-term goal of installing it on spaceborne platforms such as small satellites. The stability, durability, and cost-effectiveness of the system also need to be improved before it can be commercialized.
相关链接：Yu Hong et al, Airborne single-photon LiDAR towards small-size and low-power payload, Optica (2024). DOI: 10.1364/OPTICA.518999
Paper link: https://dx.doi.org/10.1364/OPTICA.518999
From: Light Travels the World
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