What is lidar? The new technology that opens borders using light

For many centuries the underwater exploration and archeology have been necessarily face-to-face activities, requiring the use of relatively rudimentary tools and for specialists to venture into depths and very risky environments.

Advances in the study and handling of electricity, acoustic waves, and electromagnetic waves eventually gave us a variety of equipment to observe and measure that we couldn’t before. In this millennium, , revolutionizing archeology and underwater exploration and challenging the basic premises of our historical perspective.

Light and sound

The first electrical remote measuring tool was the sonar. It emits pulses of sound underwater. The time it takes for an echo to return indicates the distance from the object where the wave bounced. when the sinking of the Titanic (1912) led to the hasty development of the first versions for ships.

The two world wars, with the development of submarines, also accelerated their progress. This became the main tool for producing seabed relief maps, a titanic task, given the vastness of the oceans and the currents and temperature variations that impact the conductivity of waves.

high frequencies – such as 300 kHz – allow more detail but at less distance or depth.

Shortly after sonar was invented, the same bouncing wave principle was applied to radio waves, the radar.

“The lidar can be coupled to a GPS to create an accurate map. Depending on the type of laser and surface, the beam can penetrate water or soil.”

The main difference is that sonar emits sound waves, pulses that are transmitted ‘hitting‘ the water, while radar emits electromagnetic waves that travel at the speed of light and whose rebound is detected by more sophisticated sensors.

Similar to sonar,

The radar it evolved rapidly after World War II, and today uses a wide range of electromagnetic waves, particularly high-frequency radio and microwave waves. Very high frequency waves can even penetrate the ground, although not to great depths. This can be used to locate pipes, rock formations, and buried objects.

From the radio to the light

From there, it was a natural step to experiment with light waves.

White light was not practical, because there is no lamp that can compete with sunlight. Even at night, the main limitation was the possibility of concentrating sufficiently powerful light beams and having sensors that allow precise range measurement at great distances. This led to experimenting with a new type of light:

This concentrates light waves into a thin, high-power beam. The color of the beam and its visibility depend on the wavelength, given by the gases and crystals that are used to produce it.

, while others are infrared bands (below red), invisible to the human eye.

Albert Einstein laid out the theoretical principles for the laser in 1917, but it was not until 1960 that the first one was produced. Its development took off at the same time as the accelerated development of digital sensors and circuits took off.

Technologies

Shortly after its invention, the To be it was used to track satellites (1961) and then in military applications, measuring distances for artillery in 1963, through the same principle that sonar and radar were based on. That led to the use of lasers for detection and ranging being baptized as lidar.

Lidar technology uses sensors that measure with great precision the delay and dispersion of the reflection of the light beam. The evolution of microcircuits and sensors in the last decade has been dizzying, and similar to today’s digital cameras, a lidar can have millions of receivers on a panel. By using a broadband laser, the new systems use indium gallium arsenide (InGaAs), which operates in the infrared spectrum with greater power, range and safety than previous lasers.

Applications

. Depending on the type of To be and surface, the beam can penetrate water or soil. For large areas it is mounted on a plane. When more detail is wanted, a helicopter or drone is used that moves slowly and close to the surface. Computers can highlight minute differences in elevation, making it possible to see variations too subtle to be noticed even by a person standing in the same spot.

Shrinking the size and cost of the technology is opening up a range of applications from agriculture and oceanography to autonomous vehicle navigation. . Topographical work in the jungle, which used to take a year, now takes only a few hours.

Thanks to lidar, thousands of buildings, temples and roads have recently been discovered in Central America, revealing an extensively urbanized Mayan civilization, which would have housed millions of inhabitants.

In Peru, lidar is already being used in archaeology. But nevertheless,

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