Prismatic systems

Another means of controlling light optically is to deflect it using a prism. It is known that the deflection of a ray of light when it penetrates a prism is dependent on the angle of the prism. The deflection angle of the light can therefore be determined by the shape of the prism.
If the light falls onto the side of the prism above a specific angle, it is not longer refracted but reflected. This principle is also frequently applied in prismatic systems to deflect light in angles beyond the widest angle of refraction and, in so doing, to cut out the light.
Prismatic systems are primarily used in luminaires that take fluorescent lamps to control the beam angle and to ensure adequate glare limitation. This means that the prisms have to be calculated for the respective angle of incidence and combined to form a lengthwise oriented louvre or shield which in turn forms the outer cover of the luminaire.