A device for amplifying a laser beam is provided. The device includes at least one amplifier chamber in which a laser-active material is provided, at least one transmitting optical member delimiting the amplifier chamber and being arranged at a tilt angle, α, with respect to a plane oriented perpendicularly with respect to an optical axis of the laser beam, and at least one detection unit. The laser beam is reflected by the transmitting optical member into a back reflected laser beam, and the detection unit is arranged such that it detects the back reflected laser beam.