A device for focusing a laser beam includes a first telescopic configuration and a second telescopic configuration. The first telescopic configuration includes a collimating optical element for collimating the laser beam and a downstream focusing optical element for focusing the laser beam onto a focal point. The second telescopic configuration includes a first lens and a downstream second lens disposed in the divergent beam path upstream of the first telescopic configuration. The first and second lenses of the second telescopic configuration are moveable relative to each other in the beam direction.