What is the green laser beam shining on Sakurajima at night?

See below for the English version.

The Sakurajima MuseumYouTube channelbroadcasts footage fromlive cameras of the Sakurajima volcano.

Regarding the green laser beam shining on Sakurajima at night, various rumors seem to have been circulating, such as "U.S. military laser gun test firing," "laser beams from a UFO," or "it's pointing toward Laputa" (laughs).

In fact, this laser beam is for observing the volcanic activity of Sakurajima, and it comes from observation equipment installed by the Sakurajima Volcano Research Center (Sakurajima Volcano Observatory) of the Disaster Prevention Research Institute at Kyoto University.
We have asked Associate Professor Haruhisa Nakamichi of Kyoto University to write an explanatory text, which we will introduce here.

At night, you can see green laser beams running from the east and west toward the crater of Sakurajima. This is light from a device called a LiDAR. LiDAR stands for Light Detection and Ranging, and it is a device that emits laser light and observes the light scattered by objects. LiDAR technology is used for distance measurement and has recently been incorporated into the iPhone 12 Pro smartphone. The LiDAR at Sakurajima was originally a Mie scattering LiDAR intended for observing atmospheric aerosol pollution; for aerosol observation, the LiDAR light was emitted directly upward. The Sakurajima LiDAR in the photo is a special model that allows the emission direction to be set freely. Currently, it is installed at the Sakurajima Volcano Observatory and the Kurokami Observation Room shown in the figure, and both are set to emit laser light over the Minamidake crater. This LiDAR device has allowed us to understand the emission and outflow of volcanic ash from the crater that is much finer than the volcanic ash visible to the naked eye.

Layout of the LiDARs installed on the east and west sides of Sakurajima. SVO indicates the location of the Kyoto University Sakurajima Volcano Observatory LiDAR, and KUR indicates the location of the Kyoto University Kurokami Observation Room LiDAR. Both emit laser light over the Minamidake crater of Sakurajima.

LiDAR device installed at the Sakurajima Volcano Observatory. The laser beam is emitted from a thin tube facing a glass window. The faint light reflected by atmospheric particles is received by a thick tube.

At night, a green laser beam can be seen running from east to west toward the Minamidake crater of Sakura-jima. This is light from a device called a LiDAR. LiDAR is an abbreviation of Light Detection and Ranging, and it radiates the laser beam and observes the scattered light from objects. LiDAR technology is used to measure distance, and recently has been incorporated into the smartphone iPhone 12 Pro. LiDAR in Sakura-jima was originally a Mie scattering LiDAR for the purpose of observation of air pollution aerosol. The Sakurajima LiDAR in the photo is a special LiDAR that can freely set the direction of light radiation. At present, it is installed in the Sakurajima Volcano Observatory and its Kurokami Branch of Kyoto University in this figure, and both are designed to emit laser light over the Minamidake crater. This LiDAR system has revealed the emission and dispersion of fine volcanic ash from the crater, which is much finer than visible volcanic ash.