Preionization arrangement for gas laser

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• and
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein an edge of said external preionization electrode near said tube is bent to point toward said tube.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• and
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein each opposed longitudinal end of the external preionization electrode includes a ring-shaped tip to prevent arcing therefrom.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• and
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein said external preionization electrode includes an ultraviolet semitransparent portion configured to partially shield the preionization unit from the main discharge area.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• an external preionization electrode coupled with said tube for producing a corona discharge from the tube when a potential difference is created between said internal and external preionization electrodes;
• and
• an ultraviolet semi-transparent mask disposed between the tube and the main discharge area.

A preionization device for a gas laser, comprising:

• an elongated internal preionization electrode;
• an elongated dielectric tube around said internal electrode;
• and
• an external electrode at a different electric potential than the internal electrode,
• wherein said internal electrode is substantially cylindrical and fills the hollow cylindrical interior space defined within said tube except that the internal electrode has a slit defined along its length which allows the internal electrode to have a faster rate of thermal expansion than said tube.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• and
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein the external electrode is electrically connected directly to said first main discharge electrode,
• wherein said external preionization electrode includes an ultraviolet semi-transparent portion configured to partially shield the preionization unit from the main discharge area.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein the external electrode is electrically connected directly to said first main discharge electrode,
• wherein each opposed longitudinal end of the external preionization electrode includes a ring-shaped tip to prevent arcing therefrom.

A corona-type preionization unit of a gas discharge laser having a discharge chamber filled with a laser gas mixture and a first and second main discharge electrodes, comprising:

• an elongated internal preionization electrode within an elongated dielectric tube;
• and
• an external preionization electrode having a cross-sectional shape formed to shield said tube from areas within the discharge chamber outside of the main discharge area between the first and second main discharge electrodes,
• wherein an edge of said external preionization electrode near said tube is bent toward said tube,
• wherein said external preionization electrode includes an ultraviolet semi-transparent portion configured to partially shield the preionization unit from the main discharge area.