The invention relates to a gas slab laser comprising a gas-filled chamber limited by a housing (1, 2, 3). The laser is provided with at least two high-frequency excited electrodes (5, 6) that extend into the housing and overlap. The electrodes define a discharge chamber (14). The laser is additionally provided with resonator mirrors (12, 13). In order to adjust the laser, the spatial arrangement of the electrodes and the resonator mirrors is optimized. Adjustment is carried out by applying a force (F) in the housing so that the spatial arrangement of the resonator mirrors is optimized as a result of the bending of the housing caused by the application of force. Deformation of the housing can occur plastically or elastically by maintaining the deforming forces.