F2-laser with line selection

US6345065B1 · kind B1 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Jürgen Kleinschmidt · Hersbruck, DE
• Peter Heist · Jena, DE
• Frank Voss · Berlin, DE
• Andreas Görtler · Bamberg, DE

Key dates

• Filing date: May 24, 1999
• Grant date: Feb 5, 2002
• Expiry date: May 24, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/1062
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost. The wavelength selection unit preferably includes a prism having a front surface oriented at Brewster's angle and a back surface oriented to receive and reflect an ordinary refracted ray travelling within the prism at a righ…