Method of and apparatus for extending electrode life in a laser chamber

A laser comprising:

• a discharge chamber;
• a first electrode positioned at least partially within the discharge chamber and fixed with respect to the discharge chamber;
• a second electrode positioned at least partially within the discharge chamber, the first electrode having a first discharge surface and the second electrode having a second discharge surface, the first discharge surface and the second discharge surface being arranged to confront one another across a gap, a polarity of the first electrode being positive with respect to a polarity of the second electrode so that the first electrode functions as an anode during a discharge in the discharge chamber, the first electrode comprising a material that forms a corrosion resistant coating when the first electrode functions as an anode during a discharge in the discharge chamber;
• a motor mechanically coupled to the second electrode to position the second discharge surface to control a width of the gap;
• and
• a controller connected to the motor wherein the controller supplies a control signal to the motor to make the width of the gap substantially equal to an original gap width.

A laser comprising:

• a discharge chamber;
• a first electrode positioned at least partially within the discharge chamber and fixed with respect to the discharge chamber;
• a second electrode positioned at least partially within the discharge chamber, the first electrode having a first discharge surface and the second electrode having a second discharge surface, the first discharge surface and the second discharge surface being arranged to confront one another across a gap;
• a motor mechanically coupled to the second electrode to position the second discharge surface to control a width of the gap;
• and
• a controller connected to the motor wherein the controller supplies a control signal to make the width of the gap substantially equal to an original gap width,
• a polarity of the first electrode being positive with respect to a polarity of the second electrode so that the first electrode functions as an anode during a discharge in the discharge chamber, the first electrode comprising a material that forms an erosion resistant coating when the first electrode functions as an anode during a discharge in the discharge chamber.

A method of controlling operation of a laser, the laser including a discharge chamber and a first electrode and a second electrode spaced apart by a gap, the second electrode being positionable to establish a width of the gap, the method comprising the steps of:

• operating the laser by causing a discharge to occur in the discharge chamber between the first electrode and the second electrode with a polarity of the first electrode being positive with respect to a polarity of the second electrode so that the first electrode functions as an anode during a discharge in the discharge chamber;
• measuring a width of the gap;
• and
• automatically controlling a position of the second electrode to make the width of the gap substantially equal to an original gap width.