Method and apparatus for wavelength calibration

US6160832A · kind A · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Jürgen Kleinschmidt · Hersbruck, DE
• Uwe Stamm · Göttingen, DE
• Klaus Vogler · Eckental, DE
• Peter Lokai · Oettingen, DE

Key dates

• Filing date: Oct 12, 1999
• Grant date: Dec 12, 2000
• Expiry date: Oct 12, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/225
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A wavelength calibration system determines an absolute wavelength of a narrowed spectral emission band of an excimer or molecular laser system. The system includes a module including an element which optically interacts with a component of an output beam of the laser within the tunable range of the laser system around the narrowed band. An inter-level resonance is detected by monitoring changes in voltage within the module, or photo-absorption is detected by photodetecting equipment. The absolute wavelength of the narrowed band is precisely determinable when the optical transitions occur and are detected. When the system specifically includes an ArF-excimer laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 193 nm and the element is preferably a gas or vapor selected from the group consisting of arsenic, carbon, oxygen, iron, gaseous hydrocarbons, halogenized hydrocarbons, carbon-contaminated inert gases, germanium and platinum vapor. When the system specifically includes F.sub.2 -laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 157 nm and the element is preferably a gas or vapor sel…