Patent ID: 7586969
Filing Date: 2009-09-08
Classification: H01S

Abstract:
1. Method for discriminating an anomaly in gas composition of a laser gas excited by discharge in a discharge tube of a laser oscillator, said method comprising: detecting an actual output current value of a high-frequency power supply unit supplying power to said discharge tube at an arbitrary pressure lower than high pressure during steady-state operation, at a start of said laser oscillator, after said laser gas begins discharge excitation at a pressure lower than said high pressure during said steady-state operation; comparing said detected actual output current value with a normal output current value that has been detected when said gas composition of said laser gas is normal at the same pressure as said actual output current value is detected; and discriminating, if a difference between said actual output current value and said normal output current value is equal to or greater than a preset value, that said gas composition of said laser gas is abnormal.