A team of researchers in northwest China says it has developed a way to use high-energy laser beams, not to destroy drones but to keep them in the air “forever”.

Many countries, including China, are developing powerful laser systems as anti-drone weapons. But Professor Li Xuelong and his colleagues from the Northwestern Polytechnical University (NPU) approached the drone-laser relationship from another angle.

They thought that if a drone was fitted with a photoelectric conversion module that converted light energy into electricity, a high-energy laser beam could not only track it, but also power it remotely.

The team, from NPU’s school of artificial intelligence, optics and electronics, said a recent experiment had successfully combined the autonomous charging process with intelligent signal transmission and processing technology – demonstrating the unlimited endurance potential for optics-driven drones (ODD).

“Highlights of the research are 24-hour intelligent vision tracking system and the autonomous long-range energy replenishment for ODD,” the team reported on NPU’s official WeChat account last week.

According to the researchers, the first challenge was to track the drones in the air. The team developed a tracking algorithm based on intelligent visuals to follow and accurately predict ODD targets as they fly.

The algorithm had good tolerance with illumination, scale and rotation, was robust in different environments, and achieved the precise positioning of drones, the report said.

To increase the distance of wireless energy transmission, Li and his team needed to reduce the attenuation of a traditional laser beam in the atmosphere. Their solution was an adaptive beam shaping technology that could autonomously adjust its intensity, they said.

The adjustment means the negative impacts of air turbulence and density changes in the atmosphere can be reduced, improving the effectiveness and reliability of long-distance laser energy delivery, according to the report.

A protection algorithm was also added to the system, automatically adjusting laser power to a safe range once an obstacle is detected in the beam’s path.

The team did not disclose details of the system’s range and photoelectric conversion efficiency, because of the sensitivity of the technology, which has potential uses in military applications.

An animated schematic illustration presented in the report suggested an ODD could fly as high as a skyscraper.

The research team said it carried out three field tests: indoor follow-up flight, outdoor daytime flight, and outdoor night flight. The drones operated successfully in all scenarios.

Drones are widely used in military, agricultural and commercial applications, but if their endurance limitations can be overcome, they will bring many new possibilities to the world.

“In some time-consuming missions, such as searching for tourists trapped in flash floods, the continuous flight of drones will greatly save precious rescue time. ODD are expected to deeply participate in social governance, such as traffic control, security patrols, rescues in disasters and contactless logistics,” the report said.

“In the future, large drones can be transformed into air buses to build a three-dimensional traffic network. We can even create a ‘low-altitude satellite’ or ‘artificial moon’ with this technology.”

Some analysts say that in a military context, autonomous ground-to-air wireless charging could amplify the advantages and efficiency of drone clusters – such as the coordinated UAV “swarm” system unveiled by China Electronics Technology Group Corporation in September 2020.