The surface of the ground is illuminated with ultraviolet radiation, inducing fluorescence in certain molecules. The emitted fluorescent emission induced by the ultraviolet radiation is measured by means of a fluorescence detector, consisting of a photodetector or video camera and filters.
When the earth's surface is exposed to ultraviolet radiation, it triggers a response in certain molecules that emit light, known as fluorescence. This fluorescent emission is then detected by a device that combines a light-sensitive detector or camera with filters.