Method and procedure to automatically stabilize excimer laser output parameters

US6490307B1 · kind B1 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Bruno Becker de Mos · Biebesheim, DE
• Uwe Stamm · Göttingen, DE
• Klaus Vogler · Eckental, DE

Key dates

• Filing date: Nov 23, 1999
• Grant date: Dec 3, 2002
• Expiry date: Nov 23, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/036
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method and apparatus is provided for stabilizing output beam parameters of a gas discharge laser by maintaining a constituent gas of the laser gas mixture at a predetermined partial pressure using a gas supply unit and a processor. The constituent gas of the laser gas mixture is provided at an initial partial pressure and the constituent gas is subject to depletion within the laser discharge chamber. A parameter such as time, pulse count, driving voltage for maintaining a constant laser beam output energy, pulse shape, pulse duration, pulse stability, beam profile, bandwidth of the laser beam, temporal or spatial coherence, discharge width, or a combination thereof, which varies with a known correspondence to the partial pressure of the constituent gas is monitored. Injections of the constituent gas are performed each to increase the partial pressure by a selected amount in the discharge chamber. A number of successive injections is performed at selected intervals to maintain the constituent gas substantially at the initial partial pressure for maintaining stable output beam parameters.