A limiting factor for remote unmanned aerial vehicles is that in order for their operators to see what their camera is capturing, the vessel must be connected to the surface support vessel by a long tether. Scientists are working to change this situation with a two-way system that uses the laser pointer to wirelessly transmit ultra-high definition video underwater.
The Underwater Wireless Optical Communications (UWOC) system was created by Abdullah Al-Halafi, a Ph.D. student at King Abdullah University of Science and Technology, and his mentor, Basem Shihada. So far, the system has been tested in a laboratory environment, successfully transmitting and receiving signals at 4.5 meters (14.7 feet) of clear ocean water and turbid seaports. It integrates an underwater platform that converts ultra-high definition digital video into a series of extremely fast pulses emitted by a 520 nanometer green laser pointer diode. These channels form a downstream channel that passes through the water and is received by a photodiode-equipped receiver and converted back to live video.
The receiver in turn uses the 450 nm blue laser pointer to form an uplink channel that passes the data back to the underwater platform. Included in this data is feedback on the signal quality of the received video. Based on this feedback, the underwater platform will adjust the power and modulation of its video signal to compensate for the deficiencies caused by the clarity of the water. This means that if the water is fairly clear, more video packets can be transmitted at a faster rate, but if it is turbid, the video quality is maintained by slowing down the video transmission rate. Al-Halafi said: "The end user will not have any difference in video quality, because the system can provide video packets with the same definition, but with optimized power and transmission rate." The data transmitted on the uplink channel is also May contain commands that the operator can use to remotely control the remote unmanned aerial vehicle. Although this is not the first UWOC system we have ever seen, it has been reported to achieve the highest resolution and fastest transfer rate of underwater video. A paper on this research was recently published in the IEEE Photonics Journal.