Abstract: A method is disclosed for controlling a pulse repetition rate of pulsed laser beam 1 created by pulsed laser oscillator 100, includes generating beam 1 by oscillator 100, splitting beam 1 into first pulsed split beam 1a and second pulsed split beam 1b, time-delaying split beam 1a relative to split beam 1b by optical delay device 220, generating timing baseband signal Sc including a timing jitter of the pulse repetition rate based on split beam 1a and second split beam 1b by timing detector device 230, generating feedback signal Sf based on timing baseband signal Sc, and applying feedback signal Sf on oscillator 100 and controlling the pulse repetition rate of beam 1 based on the feedback signal Sf. Furthermore, repetition rate control apparatus 200 for controlling a pulse repetition rate of pulsed laser oscillator 100 and pulsed laser oscillator 100, comprising repetition rate control apparatus 200 are described.