Le 19 octobre 2016, 12:25 dans Technologie • 0
In February this year, the US Laser Interferometer Gravitational Wave Observatory (LIGO) successfully detected billions of years ago the merger of two black holes in the process of space-time ripples - gravitational waves. Scientists at the Handelix Institute of Technology in the United States recently published a study in the Journal of Applied Physics that developed a small ring laser 20mw interferometer to detect ground-induced and convective storm-induced Sub-acoustic and other geophysical effects, the future of the technology can be applied to hurricanes, tornadoes and volcanic eruptions and other natural disaster early warning system.
"Essentially, we have confirmed many of the long-term results of the National Oceanic and Atmospheric Administration (NOAA), but we replaced the microphones with ring lasers." Robert Dun, professor of physics at Handelikes College, En said. The ring laser interferometer can clearly show the frequency spectrum of the infrasound, in particular, can be pointed out that the tornado to reach the ground 30 minutes before the laser can detect the tornado generated infrasound. The researchers found that infrasound waves generated by tornadoes could propagate 1000 kilometers away, confirming the results of previous NOAA studies.
How does the ring-shaped laser 10mw work? First, the laser plasma tube emits a laser beam in a clockwise and counterclockwise direction, respectively. If the laser cavity rotates in a clockwise direction, the photons that are also clockwise moved around the laser cavity will take longer and the photons that move in the counterclockwise direction will take less time. Since the speed of light is constant, the length of the path of the laser beam moving in different directions is different, and the difference in path length causes a frequency difference in turn. When the laser beams moving in the clockwise and counterclockwise directions are combined together, a "beat" corresponding to the rotation is generated. The earth has been spinning, using a horizontal ring laser can measure the Earth's rotation. Perturbation of the laser cavity changes the beat frequency of the earth. This means that the infrasound into the 5mw green laser cavity can cause disturbance, which changes the rotation of the Earth beat frequency.
The instrument can detect the infrasonic waves generated 30 minutes before the tornado reaches the ground. Combining with Doppler radar, it has a good application foreground in the early warning system. In addition, because it can detect the rotation of the seismic component, it may be possible to reduce damage caused by the earthquake. In addition to being used in a tornado warning system, ring lasers can detect infrasound waves generated by hurricanes and volcanic eruptions. Volcanic ash can destroy jet engines, ring lasers can detect distant places of volcanic eruptions, so as to ensure that the aircraft in the region flight safety. "Now all the results can be said to be only the beginning, our goal is to continue to explore the ring laser 200mw in disaster prevention and mitigation applications.