Laser gas replenishment method

US6493370B2 · kind B2 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Hans-Stephan Albrecht · Göttingen, DE
• Klaus Vogler · Eckental, DE
• Thomas Schroeder · Oettingen, DE

Key dates

• Filing date: Apr 12, 2002
• Grant date: Dec 10, 2002
• Expiry date: Apr 12, 2022

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. Injections of the constituent gas are performed each to increase the partial pressure by a selected amount in the discharge chamber preferably less than 0.2 mbar per injection. 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. The amount per injection and/or the interval between injections may be varied based on the measured value of the driving voltage and/or a calculated amount of the constituent gas in the discharge chamber. The driving voltage is determined to be in one of multiple driving voltage ranges that are adjusted based on the aging of the system. Within each range, gas injections and gas replacements are preferably performed base…