An excimer laser system in which the expensive noble gases are reclaimed, while the halogen gas is sacrificed, and the impurities developed during operation of the excimer laser are removed. In the approach disclosed a multi-stage gas purifier is used with a single, premix gas bottle containing a halogen-rich laser gas mixture comprising noble, buffer and halogen gas, to maintain the optimum halogen content of the laser, while also maintaining a consistent ratio of noble, buffer and halogen gases without complicated control apparatus.