Laser beam output control with optical shutter

A laser apparatus, comprising:

• a master oscillator configured to output a pulsed laser beam continually at a repetition rate;
• a plurality of amplifiers disposed on a beam path of the pulsed laser beam;
• a plurality of optical shutters disposed on the beam path of the pulsed laser beam;
• and
• a controller configured to switch the plurality of optical shutters, wherein
• each of the plurality of optical shutters includes:
• an electro-optic device;
• a first optical filter disposed at an input side of the electro-optic device;
• a second optical filter disposed at an output side of the electro-optic device;
• and
• a power source coupled to the electro-optic device for applying voltage to the electro-optic device, and wherein
• the controller is configured to switch the plurality of optical shutters based on a signal inputted from an external apparatus while the master oscillator oscillates the pulsed laser beam, to perform a burst operation to repeatedly alternate a period for which the pulsed laser beam is outputted at the repetition rate and a period for which the pulsed laser beam is not outputted, and to control the plurality of optical shutters to open sequentially from an upstream side optical shutter to a downstream side optical shutter.