PURPOSE: To automatically make the optimal discharge timing even when the optimal discharge timing of a device itself fluctuates so as to obtain laser light always stable and large in output by measuring a discharge time difference between an oscillator and an amplifier by a discharge timing measuring means for comparing it with the set value to correct timing and automatically adjust discharge timing in an amplifying optical system.

CONSTITUTION: A trigger signal as a discharge timing signal to be outputted from a trigger signal generator 4 is inputted to the respective power sources 3-1 to 3-N of a CVL oscillator 1 and CVL amplifiers 2-1 to 2-N is inputted for performing discharge. A current prove is provided inside a discharge circuit and a signal to be outputted is inputted in a timing measuring equipment 5. The timing measuring equipment 5 measures a discharge time difference out of an input signal to output the measured signal to a control device 6. In the control device 6, operation is performed out of an actual discharge time difference and a discharge time difference of the preset optimal discharge timing to renew delay time for being automatically adjusted.