The ball optics allows workpieces to be welded without a clamping unit - typically foils or technical textiles. The glass ball focuses the laser beam on one hand and presses the workpieces together by the compressed air behind the ball on the other.
The ball moves freely in the cylindrical shaft and can thus roll over the workpieces with the movement of the ball optics. If the ball is lifted off from the workpieces, the ball closes the opening at the bottom of the shaft and no compressed air is consumed anymore.