| 摘要 |
PURPOSE:To extend the minimum-to-maximum ratio of output to 1/100 or over by a method wherein output control is made by extinguishing a part of discharge regions and the number of extinguished parts is electrically set by an output control value in a gas laser having a plurality of discharge regions. CONSTITUTION:A switch 30 is provided at one discharge electrode 2a and half of discharge regions, that is 2a 2b, is turned off upon request. An arithemetic unit 7a compares the voltage in an output controller 31 with the output in a detector 6 to control a current source 8. The output in the controller 31 is compared 33 with a reference voltage 32 and if the output is higher than a reference value, the switch 30 is closed. The switch 30 is opened at output Ps along two-section discharge characteristics P1 by successively reducing the output in the controller 31 from a maximum value ad the output is stably supplied at the minimum output P2min along one-section characteristics P2. In this way, the output can continuously be controlled over a wide range and with stability. When two discharge regions exist, the maximum-to-minimum output ratio of 100:1 or over can be obtained. |
