The world's first fully submerged Lidar underwater transceiver system based on single photon detection technology has been developed by the University of Edinburgh

LiDAR, or laser radar, has the ability to capture 3D data about target objects and their surroundings and has recently been used in a number of mass-consumer applications, including self-driving cars and smartphones.

Another potential application for Lidar is underwater 3D imaging, which is mounted on autonomous seabed vehicles and could provide a potential way to map the ocean floor at centimetre resolution.

According to Myms Consulting, recently, A research project at Heriot-Watt University and The University of Edinburgh has developed what is claimed to be the world's first fully submerged Lidar underwater transceiver system based on single-photon detection technology, And in the journal Optics Express as "Submerged single-photon LiDAR imaging sensor used for real-time 3D scene reconstruction in The research results were released under the title scattering underwater environments.

Obtaining 3D images using lidar in seawater can be challenging because of the limited penetration of light and the scattering and distortion of any particles in seawater. However, recent advances in single-photon detection could help overcome these obstacles.

According to the research project, Heriot-Watt University's silicon based single photon avalanche diode (SPAD) detector, built in CMOS, uses picosecond resolution time-dependent single photon counting to measure photon time of flight (ToF). The high sensitivity of this lidar architecture allows it to capture detailed 3D information even in extremely low light conditions under seawater.

(a) single photon lidar schematic diagram; (b) Photo of optical setup based on SPAD detector array

An underwater lidar system developed by researchers that uses single-photon detection technology to capture 3D images in fully submerged water. To demonstrate the lidar system, the researchers used it in a water tank to get a 3D image of a pipe (pictured right) (pictured left).

Aurora Maccarone, one of the researchers from Heriot-Watt University, said: "This lidar technology has a wide range of applications. For example, it could be used to examine underwater facilities, including underwater structures for wind farm cables and turbines. Underwater Lidar can also be used to monitor or measure underwater archaeological sites and for security and defense applications."

According to a paper published in the research project, the lidar system operates at a central wavelength of 532 nanometers and is based on a silicon-based CMOS SPAD detector array of 192 x 128 pixels.

The research team also used two recently developed analytical algorithms, one specifically developed at Heriot-Watt University for real-time 3D scene reconstruction from single-photon data in lidar applications, and the other recently proposed for range estimation in highly scattered underwater environments.

"Heriot-watt University has a long track record in single photon detection technology and image processing of single photon data, which allows us to demonstrate advanced 3D imaging technology in extremely challenging conditions." "Fundamental advances made at the University of Edinburgh in the design and manufacture of a single photon avalanche diode (SPAD) detector array have enabled us to build compact and powerful 3D imaging systems based on the single photon detection technology," said Maccarone.

Experiments were conducted in 4 m x 3 m x 2 m tanks at three different turbidity levels, demonstrating 3D imaging of stationary and moving objects in a controlled high-scattering underwater scene over a distance of 3 m and successfully recording real-time 3D video of moving objects at ten frames per second.

The experimental diagram shows the underwater transceiver, external control and laser source module, target object position and transmisometer

"Our work aims to make single photon detection techniques usable in underwater environments, meaning we will be able to 3D image scenes of interest in very low light conditions." Aurora Maccarone said, "The technology will affect the use of offshore cables and energy installations. It will also allow unattended Marine monitoring, which means less pollution and intrusion into the Marine environment."

Source: NetEase