However, this surface has a much longer decay time which is ideally suited for viewing pulsed lasers. Depending on the illumination conditions, the image retention time can be varied from one tenth of a second to several minutes. The more intense the UV illumination, the shorter the persistence. When no UV illumination is used, and when the background illumination is dimmed, the phosphorescence of the surface will retain the laser beam pattern for several minutes. This surface operates on a different principle than previously described.
Energy is stored in the phosphor surface when it is exposed to fluorescent room lights or UV light.
Near IR radiation stimulates the release of this energy as yellow-orange light. Consequently, the beam appears as a bright image on a dark background. After the phosphors have absorbed a given amount of IR energy, the surface can become depleted. The beam must then be moved to a new area of the surface or the surfaced recharged. All plate and imaging surfaces have a matte finish for safe beam displays.