The invention relates to a method for producing a transparent substrate comprising a pattern with a refractive index modulation. According to said method, a transparent substrate is irradiated by means of laser radiation focused on the substrate in the form of at least one laser line, where the substrate at least partially absorbs the laser radiation, a relative movement of the substrate and the laser line focused on the substrate is imposed in a direction (X) transverse to the longitudinal direction (Y) of the laser line, and during said relative movement, the power of the laser line is temporally modulated according to the speed of relative movement and the dimensions of the pattern in the direction (X) of relative movement.