An oscillator-amplifier gas discharge laser system and method is disclosed
which may comprise a first laser unit which may comprise a first
discharge region which may contain an excimer or molecular fluorine
lasing gas medium; a first pair of electrodes defining the first
discharge region containing the lasing gas medium, a line narrowing unit
for narrowing a spectral bandwidth of output laser light pulse beam
pulses produced in said first discharge region; a second laser unit which
may comprise a second discharge chamber which may contain an excimer or
molecular fluorine lasing gas medium; a second pair of electrodes
defining the second discharge region containing the lasing gas medium; a
pulse power system providing electrical pulses to the first pair of
electrodes and to the second pair of electrodes producing gas discharges
in the lasing gas medium between the respective first and second pair of
electrodes, and laser parameter control mechanism modifying a selected
parameter of a selected laser output light pulse beam pulse produced by
said gas discharge laser system by controlling the timing of the
occurrence of the gas discharge between the first pair of electrodes and
the occurrence of the gas discharge between the second pair of
electrodes.