Etching of coated substrate

A method for etching a pattern on a coating deposited on a substrate, said substrate scrolling at a scrolling velocity, said pattern being produced by a treatment unit generating a laser beam in the form of an etching point capable of being moved in a scrolling direction with a first amplitude at a first velocity greater than the scrolling velocity over at least one line portion and in a direction orthogonal to the scrolling direction with a second amplitude at a second velocity over at least one line portion, said method comprising, during the scrolling of the substrate:

• etching a first line of a length between and a first etching start point (PD1) and a first etching end point (PA1);performing at least one etching of another line (ni+1), said at least one etching consisting in:
• moving the laser beam from an etching end point (PAi) of a previously etched line (ni) that extends along the scrolling direction to an etching start point (PDi+1), said etching start point (PDi+1) of said other line (ni+1) being offset from the etching end point (PAi) of said previously etched line (ni) by a distance (dx) in the scrolling direction and by a distance (dy) in the direction orthogonal to the scrolling direction, etching said other line (ni+1) of a length between said etching start point (PDi+1) and an etching end point (PAi+1);
• moving the beam from the etching end point (PAi+1) to the first etching end point (PA1) before a length of the other line (ni+1) exceeds the first or second amplitude of the laser beam.