Innovate UK-funded project proves that a programmable lens can steer a laser beam on to moving aircraft and bounce it back, laden with data.
Sending large packets of data to the ground from an aircraft or even a satellite is not at all straightforward.
The spectrum of radio frequencies is over-subscribed and there is just no room for the extra radio traffic.
That is a potential stumbling block for the many new businesses being set up to exploit advances around satellite-derived data technology and unmanned aircraft surveying or similar applications.
Lasers offer solution
Laser technology offers a solution. It lends itself to higher speed data transfers than radio waves and is not subject to radio frequency (RF) spectrum licensing.
Yet keeping a laser beam fixed on a drone flying at 10 metres per second and being buffeted by air currents poses difficulties.
Infrared light is safe and travels further
Installing a laser on the aircraft is impractical because of size and weight constraints. However, the team proved they could establish a data connection using a programmable reflective lens to steer the laser beam on to a UAV (unmanned aerial vehicle) and then ‘bouncing’ it back to the ground.
Project leader Yoann Thueux explained: “A modulated retro-reflector on the UAV encodes the data before the beam is then reflected back, transformed into an electrical signal.
We use infrared light, which is invisible, safe, and travels further than visible light.”
The really clever innovation was using a solid-state technology to steer the beam so accurately that it could maintain the data link connection. Yoann added:
The laser beam pointing has to be very accurate in tracking a device measuring no more than 50mm square on a moving UAV more than a kilometre away. We have tested this to 1.2 kilometres. With more laser power, we could go to longer distances.
We have had very good results. This laser technology is limited by weather conditions and we’re not suggesting it will completely replace low data-rate RF communications for control and safety. However, this technology will allow you to download a massive amount of data when you have good visibility.