Patent ID: 7843978

Claim:
A method of varying a laser pulse repetition rate of a passively q-switched laser, comprising: a) providing a laser cavity including a gain element and means for passive q-switching; b) providing a sequence of pump pulses into the gain element, said sequence of pump pulses having a pulse period T 1 for producing a pulsed laser radiation at a first repetition rate, wherein individual pump pulses in the sequence of pump pulses are preceded by pump pre-pulses formed of pump radiation having a pulse power level lower than the pump pulses and insufficient to cause lasing; c) changing the pulse period of the sequence of pump pulses from T 1 to T 2 so as to produce pulsed laser radiation at a second repetition rate; and, d) adjusting the pulse power of the pump pre-pulses so as to compensate for a change in a thermal loading of the gain element due to the changing of the pulse period from T 1 to T 2 , wherein the pulse power of the pump pre-pulses is increased if T 1 is smaller than T 2 , and is decreased if T 1 is greater than T 2 .