Extreme ultraviolet light source device, laser light source device for extreme ultraviolet light source device, and method for controlling saturable absorber used in extreme ultraviolet light source device

A pulse laser device, comprising:

• a laser oscillator for outputting a pulse laser beam;
• at least two amplifiers for amplifying the laser beam that is output from the laser oscillator;
• and
• a saturable absorber device, disposed on an optical path between the laser oscillator and the amplifier, or on an optical path between the amplifiers, for absorbing at least a laser beam having light intensity not greater than a predetermined value and suppressing laser beam transmission, the saturable absorber device comprising:
• a saturable absorber cell having a main body unit that has a flow space where the saturable absorber flows;
• an inlet for letting the saturable absorber enter the flow space;
• an outlet for letting the saturable absorber out from the flow space;
• a window for passing the output laser beam from the laser oscillator to the flow space;
• a mirror disposed in the flow space to reflect the laser beam traveling through the window,
• a cooling mechanism configured to cool the mirror;
• a pipeline for connecting the inlet and the outlet;
• a transport unit, disposed in the middle of the pipeline, for transporting the saturable absorber that flows out of the outlet, so as to flow into the flow space via the inlet;
• and
• a temperature adjustment unit, disposed in the middle of the pipeline, for adjusting temperature of the saturable absorber transported by the transporting unit.

A laser device comprising:

• an oscillator configured to output a laser beam;
• amplifiers configured to amplify the laser beam from the oscillator;
• a gas cell disposed between the oscillator and one of the amplifiers or between the amplifiers;
• and
• a reservoir for a gas including a nitrogen gas or a rare gas, wherein
• the gas cell includes:
• an inlet through which the gas flows into the gas cell;
• an outlet through which the gas flows out from the gas cell;
• a first window through which the laser beam is introduced into the gas cell;
• a mirror disposed in the gas cell to reflect the laser beam introduced through the window;
• and
• a cooling mechanism configured to cool the mirror.

An extreme ultraviolet light source device for generating extreme ultraviolet light, the device comprising:

• a chamber;
• a target material supply configured to supply target material into the chamber;
• an oscillator configured to output a laser beam;
• amplifiers configured to amplify the laser beam from the oscillator;
• a focusing optical system configured to focus the laser beam amplified by the amplifiers to a spot in the chamber where the target material is irradiated with the amplified laser beam;
• and
• a gas cell disposed in an optical path of the laser beam between the oscillator and the spot in the chamber;
• and
• a reservoir for a gas including a nitrogen gas or a rare gas, wherein
• the gas cell includes:
• an inlet through which the gas flows into the gas cell;
• an outlet through which the gas flows out from the gas cell;
• a first window through which the laser beam is introduced into the gas cell;
• a mirror disposed in the gas cell to reflect the laser beam introduced through the window;
• and
• a cooling mechanism configured to cool the mirror.