It is understood that in addition to autonomous driving, land survey is also one of the main applications of laser pointer radar. However, due to the influence of environmental factors, it is inevitable that the laser radar will have some blurring effects in the land survey. Recently, the US Naval Research Laboratory in Washington, DC, proposed a new method that uses a specially designed laser system and gated digital holography, so that lidar can eliminate blurred terrain elements, such as ground leaves or tree crowns.
The light emitted by the traditional lidar system has very little original light reaching the ground due to the blocking of the leaves. At the same time, too much light reflected back before reaching the ground will hide the ground return signal.
The researchers said: “The newly developed technology can project the laser beam through the hole of the blade, so that the lidar can see the blocked part. The key is to eliminate the interference between the two laser beams on the sensor. With a width of only a few nanometers The pulses emitted by the pulsed laser and the gated measurement with similar time resolution, the holographic system can selectively block the earliest arriving light reflected from the occlusion, and then the camera can only measure the reflection back from the partially hidden surface Light. ”
Research teams from Sandia National Laboratory and the University of Toronto have made breakthrough progress in miniature terahertz light sources, successfully increased the power output of terahertz lasers by 80%, and are expected to be widely used in industrial imaging and chemical detection.
Currently, the project has gained favor for measuring oxygen content to explore the components of interstellar medium. Because the terahertz laser source has the problem of emitting a green laser pointer in the opposite direction, its actual output efficiency is low, and at least half of its energy is wasted in vain, which limits its application.