PURPOSE: To prevent effectively the temperature of metal electrodes from rising to reduce the difference of extension between the metal electrodes and a discharge tube owing to thermal expansion, thereby preventing effectively the discharge tube from being damaged, by forming cooling fins on the periphery of the metal electrodes which are disposed on the periphery of the discharge tube.
CONSTITUTION: Laser medium gas 6, which is charged into a discharge tube 1 of a gas laser apparatus, is forced to circulate through a duct 8 having a blower 7, heat exchangers 8a and 8b in the line thereof. Metal electrode 2a and 2b are disposed on the periphery of the discharge tube 1 and cooling fins 10a and 10b are disposed on the respective electrodes 2a and 2b. And the heat of the electrodes 2a, 2b exposed in the center part is radiated into the outside air through the respective fins 10a, 10b to prevent the temperature of the electrodes 2a, 2b from rising, thereby the extension of the electrodes 2a, 2b being reduced to decrease the difference of the extension between the electrodes 2a, 2b and the discharge tube 1. The high frequency voltage from a high frequency power supply is applied to both of the electrodes 2a, 2b of this apparatus to generate the high frequency discharge 11, thereby the gas therein is excited and the laser is oscillated in the resonator which is comprised of a total reflecting mirror 5 and an output mirror 4 to output a laser beam 12.
TERAI KIYOHISA
KANEKO EIJI
