| 摘要 |
PURPOSE:To surely follow a change in the power due to a partial exchange of a laser gas and to obtain the stable output power by a method wherein, when a gas has been exchanged partially, a partial gas exchange control mode is executed at least until a prescribed time elapses. CONSTITUTION:In an output control operation of a narrow-band oscillation excimer laser, a control operation at a partial gas exchange (PGR) is executed by a time management method. When it is judged that an impressed voltage Vch to an electrode has become larger than a value A, a value T is cleared to 0; after that, the partial gas exchange is started in order to exchange a laser gas inside a laser chamber 107 and to adjust a component of the laser gas inside the laser chamber 107. When the partial gas exchange is started, a partial gas exchange (PGR) mode control subroutine 404 is selected. When the partial gas exchange is executed, the partial gas exchange mode control subroutine 404 which is suitable for the partial gas exchange is executed only for a definite time (time B). The partial gas exchange mode control subroutine 404 is repeated until the elapsed time T has reached the set time B. |
