Master oscillator—power amplifier excimer laser system

An excimer or molecular fluorine laser system comprising:

• a master oscillator including therein a first discharge chamber filled with a first gas mixture, the first discharge chamber containing a plurality of electrodes connected to a discharge circuit for energizing the first gas mixture and generating a pulsed laser beam;
• a power amplifier including therein a second discharge chamber filled with a second gas mixture, the second discharge chamber containing a plurality of electrodes connected to a discharge circuit for energizing the second gas mixture to define a gain region for amplifying the pulsed laser beam, said power amplifier having an entrance end and an exit end;
• and
• a set of reflective optics positioned about the power amplifier so that at least a portion of the pulse exiting the exit end of the power amplifier after a first pass therethrough is directed around the outside of the power amplifier and then redirected back into the entrance end thereby making a second pass through the power amplifier and wherein the first pass propagates through a first portion of the gain region of the power amplifier and the second pass propagates through a second portion of the gain region of the power amplifier, said first and second portions being substantially different.

An excimer or molecular fluorine laser system comprising:

• a master oscillator including therein a first discharge chamber filled with a first gas mixture, the first discharge chamber containing a plurality of electrodes connected to a discharge circuit for energizing the first gas mixture and generating a pulsed laser beam;
• a power amplifier including therein a second discharge chamber filled with a second gas mixture, the second discharge chamber containing a plurality of electrodes connected to a discharge circuit for energizing the second gas mixture to define a gain region for amplifying the pulsed laser beam, said power amplifier having an entrance end and an exit end;
• and
• a set of reflective optics positioned about the power amplifier so that at least a portion of the pulse exiting the exit end of the power amplifier after a first pass therethrough is directed around the outside of the power amplifier and then redirected back into the entrance end thereby making a second pass through the power amplifier and wherein the first pass propagates through a first portion of the gain region of the power amplifier and wherein the beam is expanded after the first pass so that the second pass propagates through a larger portion of the gain region of the power amplifier.