A laser apparatus includes a base frame extruded in one single piece of light alloy metal which determines a chamber intended to receive the laser generator cavity, incorporated within the chamber. The plane of the lower base of the chamber coincides with the base plane of the extruded base, and the lateral faces of the chamber are directed towards opposed lateral faces of partition walls of the extruded base, with controlled clearance to permit the expansion of the laser generator cavity without mechanical stresses being produced on same, capable of deforming it.