Patent ID: 8855166

Claim:
A high repetition rate gas discharge laser system comprising: a gas discharge chamber capable of outputting more than 4000 discharges per second, the gas discharge chamber having: at least one set of gas discharge electrodes including a first gas discharge electrode and a second gas discharge electrode; a discharge region formed between the first gas discharge electrode and the second gas discharge electrode; and an output laser light pulse beam path passing between the first gas discharge electrode and the second gas discharge electrode; a hot chamber output window heated by the operation of the gas discharge laser chamber; an output laser light pulse beam path enclosure enclosing a path of the output laser light pulse, the beam path enclosure being disposed downstream of the hot chamber window and comprising an ambient temperature window, the hot chamber output window optically aligned with the discharge region and the output laser light pulse beam path through the output laser light pulse beam path enclosure; an intermediate window disposed intermediate to the hot window and the ambient window, the intermediate window and the ambient window forming a cooled section of the beam enclosure; a purge gas inlet disposed between the intermediate window and the hot chamber window, a helium source coupled to the purge gas inlet; and a cooling mechanism cooling the beam path enclosure intermediate to the intermediate window and the ambient window, the cooling mechanism configured to cool the output laser light pulse beam path within the cooled section of the output laser light pulse beam path enclosure, thereby reducing an amount of beam disturbance due to thermal boundary layers in the cooled section.