How does fluorescent ACRYLITE® sheet work?
Special fluorescent dyes are used in Roehm America's ACRYLITE® Premium (FF) fluorescent acrylic sheet. These dyes are luminous as long as light is falling on them because, instead of converting the absorbed portion of this light energy into heat, they emit it again as longer-wave light. This is the property of fluorescence.
The "fluorescent light" emitted by the dyes in the sheet is piped to the sheet edges similarly to how an optical fiber pipes light. This "light piping" is governed by the laws of geometric optics concerning light refraction and total internal reflection when light passes from a medium of higher optical density (the acrylic) to one of lower optical density (air). These laws determine that only a small proportion of the fluorescent light can be emitted at the sheet surface. Most of it is repeatedly reflected back into the material (total internal reflection) and, in this way, it is transmitted through the acrylic until it comes to an interface through which it can emerge. Such interfaces are the perimeter edges or other deliberately created "edges" on the acrylic from which the collected light can emerge.
The dyes used react both to direct sunlight and to diffuse daylight. As for artificial light sources, the light wave spectrum emitted must contain the wavelength range to which the dyes concerned will react (370-550nm).
Because a fluorescent colored sheet relies on ambient light to cause the dyes in it to fluoresce, the brightness of the edge of the sheet will depend on how much light is received by the sheet. In particular, the area of the surface exposed to the ambient light is critical. For a bright sheet edge, the ratio of exposed sheet surface area to edge area must be at least 8:1. Best results are achieved at ratios of about 16:1.