| 摘要 |
A method is provided for determining the status of a gas mixture of a laser system including a gas discharge laser which generates an output beam and has a discharge chamber containing a gas mixture within which energy is supplied to the gas mixture by a power supply via application of a driving voltage to a discharge circuit. A master data set of an output parameter such as any of output beam energy, bandwidth, spectrum width, long axial beam profile, short axial beam profile, beam divergence, energy stability, energy efficiency, width of the discharge, temporal beam coherence, spatial beam coherence, spatial pulse width, amplified spontaneous emission and temporal pulse width versus an input parameter such as driving voltage is generated corresponding to an optimal gas mixture status, preferably after a new fill and typically at the factory, and alternatively following a new fill at the fab. Preferably several master data sets are measured and stored following new fills corresponding to various ages and other conditions of the laser system. The master data set is stored into a memory of the control system. Several more calibration data sets are also preferably generated corresponding to other gas mixture or laser operating conditions. At another time, during a check sub-routine preferably during a subsequent start-up procedure or during each subsequent start-up procedure, a current status data set of the output and input parameters is generated corresponding to the current status of the gas mixture. The current status data set is then compared with the master data set and deviations of the current status and master data sets are noted. A follow-up procedure may be performed, preferably automatically as initiated by the processor, based on the comparison.
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