A laser for generating pulsed laser radiation. An element is arranged in the resonator to generate laser radiation having the first wavelength by frequency conversion of the primary radiation. The resonator is switchable into a first state in which it is open to the primary radiation, and a second state in which it is closed to the primary radiation, and is open to laser radiation of the first wavelength in both states. A control unit switches the resonator from the first to the second state so that the primary radiation begins to oscillate and the pulse generation by frequency conversion begins, switches the resonator from the second to the first state, whereby primary radiation is coupled out from the resonator. It is possible to set the duration between both steps and/or the coupling-out behavior of the resonator to adjust the pulse duration via the control unit.