Taking 3D images underwater is tricky due to inconsistent lighting conditions and particles in the water that scatter light and cause distortion. Researchers have created a novel prototype system that uses quantum technology and LiDAR to overcome these difficulties.
Light detection and ranging (LiDAR) systems create images by measuring how long a pulsed laser light takes to be reflected off objects and travel back to the system’s receiver, otherwise known as "time-of-flight." LiDAR is often used to obtain high-res 3D images for security and defense.
Now, researchers from Heriot-Watt University and the University of Edinburgh in the UK, have designed a prototype LiDAR system to take 3D images of underwater objects. The system uses a pulsed green laser to illuminate the object before thousands of single-photon (quantum) detectors pick up the reflected laser light.
Given the high number of detectors used, many hundreds of events are produced each second, making it difficult to quickly process the data needed to create real-time 3D images. To overcome this problem, the researchers developed algorithms specifically designed to process images in scattered light conditions and applied them to graphics processing unit (GPU) hardware.
The researchers set about testing their prototype by submerging it in a tank full of cloudy water. They were able to take real-time 3D videos at a distance of 9.8 ft (3 m) in three increasing levels of cloudiness, including videos of moving targets.
The study's results, say the researchers, highlight the benefits of using quantum detection technology to create imaging devices that can be used in traditionally challenging environments.
“Single-photon technologies are rapidly developing, and we have demonstrated very promising results in underwater environments,” said Aurora Maccarone, lead author of the study. “The approach and image processing algorithms could also be used in a wider range of scenarios for improved vision in free space such as in fog, smoke or other obscurants.”
The researchers foresee the technology device being used to inspect underwater infrastructure such as telecommunications cables or to survey submerged archeological sites.
The next step, say the researchers, is to reduce the size of their device so that it can be integrated into an underwater vehicle.
The study was published in the journal Optics Express.
Source: Optica
