The direction-dependent emission of light from a lamp is referred to as the radiation characteristic. It can be influenced by apertures, lenses, grids or reflectors and can can be represented, for example, in light intensity distribution curves. Depending on the shape of these curves, a distinction is made between symmetrical and asymmetrical radiation characteristics.
Symmetrical shape
usually have a symmetrical one light cone. The beam angle is rotationally symmetrical and the cone is perceived as a circle on a vertically illuminated surface.
Asymmetrical shape
Especially when flooding, an even illuminance should be achieved , for example to uniformly illuminate pictures, walls or other flat surfaces. Since the luminaire often has to be attached to the side or above the surface to be illuminated, asymmetrical beam characteristics are suitable for this. The light exit can be shaped using an asymmetrical reflector in such a way that the spread to one side is reduced. With wall washers the floor portion of the lighting is additionally limited by suitable panels.
