Patent ID: 7386019

Claim:
An apparatus for generating electromagnetic radiation pulses comprising a mode-locked laser oscillator comprising an oscillator cavity defining an oscillator beam path, a first gain element, first pumping means for pumping said first gain element, and a mode locker, and being operable to produce a train of seed electromagnetic radiation pulses; an optical switch placed outside of the oscillator beam path and being arranged in a beam path of radiation coupled out from the oscillator, the optical switch operable to couple radiation from a switch input into a switch output during a certain time period or certain time periods; a radiation amplifier including a second gain element, the radiation amplifier being arranged in a beam path of radiation radiated from the switch output, the radiation amplifier further including second pumping means, the second pumping means comprising a continuous-wave pump radiation source; and a power radiation amplifier including a third gain element and third pumping means for the third gain element, the power radiation amplifier being arranged in a beam path of radiation output from the radiation amplifier, wherein the average output power of the radiation amplifier is adjusted to the gain material saturation value of the third gain material and the number of passes of the beam path through the third gain material, and wherein the power radiation amplifier, in a normal operation mode of the apparatus, is operated in or near saturation.