The invention provides an apparatus for reducing, or eliminating, ambient air in connection with an excimer laser annealing process. Nozzles are provided to direct a flow of gas, preferably helium, neon, argon or nitrogen, at a region overlying the target area of an amorphous silicon layer deposited on an LCD substrate. The nozzles direct a flow of gas at sufficient pressure and flow rate to remove ambient air from the region overlying the target area. With the ambient air, especially oxygen, removed, the laser can anneal the amorphous silicon to produce polycrystalline silicon with less oxygen contamination. In a preferred embodiment, an exhaust system is also provided to remove the gas.