In the last years the laser marking market has experienced strong growth with demanding requests for the management not only of flat surfaces but also of complex three-dimensional shapes. Traditional marking systems consist of laser sources coupled to scanning heads for laser beam movement and f-theta focusing lenses, which concentrate all the laser energy within an almost point-like spot. However, this scenario is limited by fixed working distances with very narrow focusing tolerances. Gap Laser Systems has decided to develop a proprietary 3D optical module, a compact, automatic and easy-to-use optical solution for 3-axis laser marking applications, which allows to keep the focus of the laser beam constant, in different situations such as staggered, inclined planes, curved and irregular surfaces. This new system uses the optical features of a particular liquid lens (tunable liquid lens), so as to guarantee:  excellent process quality  system stability and reliability, with no moving parts ( no external focal lens )  high performance in terms of execution speed and available marking volumes The optical module can be applied to the following laser marking sources:  AQS10 ( 10W @ 1064 nm - DPSS )  TYL 12 ( 12W @ 1064nm - DPSS )  All the fiber laser marking sources from 20W till 50W ( ORION or SIRIO ) The main difference between a 2D marking system and a 3D system is the so-called depth of field ∆z, i.e. the tolerance in z within which the diameter of the laser spot can be considered constant and the laser process uniform: for a 2D marking system with 160mm f-theta, the ∆z value is equal to a few tenths of a millimeter; for a 3D system the range ∆z is much wider and for the specific system developed by Gap Laser Systems it is equal to about 130 mm in a configuration similar to f160.