Navigation is not possible without charts. Charts are the signposts of the sea navigation, charts and navigation are closely related.

Yes, the depths of the sea reefs, shoals and icebergs, is the ship navigation of the roadblock and the "stone", always on the navigation of the ship to pose a threat.

See, charts are so important to navigation! It is like the eyes of the navigator.

But although charts are so important, it is not easy to draw an accurate chart.

This is because, under the waters of the different landforms, the sea floor is uneven, the reefs are hidden, which for the less developed science and technology in the past, the difficulty to know how great!

With laser technology, it is possible to help people draw accurate nautical charts. Australian Navy, the use of laser technology to draw accurate nautical charts, carried out a bold exploration, put forward a practical measurement program.

They will be a laser bathymetric instrument set in a modified "Fokker" airliner, from the aircraft can be launched at the same time a beam of 0.532 microns of blue laser and a beam of 1.064 microns of infrared laser.

When the infrared laser reaches the surface, it is reflected back to the airplane.

The blue laser can pass through seawater to the bottom of the ocean, where it is reflected back to the airplane by objects such as reefs.

Thus, by measuring the round trip times of the two laser beams separately, the altitude at which the airplane leaves sea level and the depth of the seafloor can be measured at the same time. Thus, subtracting the two altitudes gives the depth of the sea.

In the actual measurement process, the Australian Navy's scientists and technicians, by rotating the reflector, so that the beam scanned back and forth, so that, at the same altitude of the flight, can be measured 207 meters wide sea surface. That's 168 measurements per second.

It is not difficult to imagine that after a proper time of continuous flight, a larger range of seabed depths can be measured, so that an overall understanding of the location, height and size of the area of the reefs can be made into an accurate nautical chart.

The world's oceans cover an area of more than 360 million kilometers2, accounting for 71 percent of the Earth's total area.

The seabed is rich in mineral deposits, like a huge magnet attracting people to develop and utilize. However, the darkness of the seabed has made underwater exploration extremely difficult.

If you enter the water with other light sources, the light source is illuminated in all directions, and the illuminated area is far from the ideal limit. However, the advent of laser technology has brought light to the exploitation of undersea treasures.

Wave light range in 450 ~ 530 nanometers of blue and green laser, penetrate the water is very strong, can enter the ocean hundreds to thousands of meters deep. For people to comprehensively develop and utilize the seabed resources to provide an ideal "light source" guarantee.