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 .