A light emitting system (1) for outputting a light beam comprising: an optical arrangement comprising at least one light source, for emitting a light beam having a determinate width and a determinate length on a projection plane placed at a determinate distance from the optical arrangement, an optical device (2) movable into a plurality of angular positions, by rotation around a rotation axis (Z1), and comprising optical elements arranged for varying the width of the light beam when the optical device is rotated.