The Atmospheric Lidar Observatory, on the Utah State University campus, will add a potassium lidar to its existing Rayleigh scatter system in the near future. The current system accurately measures temperatures from 40 km to 85 km in altitude.

Beginning at 80 km, a potassium layer forms due to the disintegration of meteors as they enter earth’s atmosphere. ALO plans to probe this layer using an alexandrite laser scanning a wavelength region near 770 nm, where potassium absorbs light. When the light is re-emitted, it can be measured in the same manner as scattered light in a Rayleigh lidar.

Usually, the return signal is proportional to the number density of potassium atoms. However, if the laser light is too powerful, the potassium layer will become saturated and the return signal will be weaker than it should be.