Patent ID: 6563853
Filing Date: 2003-05-13
Classification: G03F,H01S

Abstract:
An excimer or molecular fluorine laser system, comprising:a discharge chamber containing a gas mixture initially having a predetermined composition of gas species including at least a species containing halogen; a plurality of electrodes connected to a power supply circuit for energizing the gas mixture by applying driving voltages to the electrodes to thereby discharges that provide a beam of laser pulses controlled around approximately a target energy; a resonator for generating a laser beam substantially comprising a stimulated emission component and a relatively small amplified spontaneous emission (ASE) component, and wherein the ASE component signal is more sensitive to the gas mixture composition than the driving voltages applied to produce the beam at the target energy; a processor; and means for monitoring the amplified spontaneous emission (ASE) signal of the laser, and wherein the processor receives a signal from the ASE monitoring means indicative of the ASE signal of the laser, and based on said signal, said processor determining whether to initiate a responsive gas replenishment action for adjusting the gas mixture to the predetermined composition, and wherein said initiation determination is more precise based on said ASE signal than based on a signal indicative of driving voltages applied to produce the beam at the target energy as a result of the ASE signal being more sensitive.