System and method for protecting a seed laser in an EUV light source with a Bragg AOM

A method and apparatus for protecting the seed laser in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system are disclosed in one embodiment, a Bragg AOM is used as a switch on the beam path from the seed laser to other optical components and ultimately to an irradiation site. Power is applied to the Bragg AOM and pulses from the seed laser are thus deflected onto the desired beam path rather than passing straight through the Bragg AOM. Once the pulses have passed through the Bragg AOM, power to the Bragg AOM ceases, so that any reflections from the irradiation site will pass straight through the Bragg AOM and will not be deflected back to the seed laser. Use of the Bragg AOM rather than components previously used results in lower power consumption and better protection for the seed laser.