Absolute wavelength calibration of lithography laser using multiple element or tandem see through hollow cathode lamp

US6580517B2 · kind B2 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Peter Lokai · Oettingen, DE
• Thomas Schroeder · Oettingen, DE

Key dates

• Filing date: Feb 22, 2001
• Grant date: Jun 17, 2003
• Expiry date: Apr 19, 2021

Classification

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

Abstract

A tunable laser system includes a gain medium and an optical resonator for generating a laser beam, and a spectral narrowing and tuning unit within the resonator. A detection and control unit controls a relative wavelength of the laser system. A wavelength calibration module calibrates the detection and control unit. The module contains more than one species each having an optical transition line within the tuning spectrum of the laser. A beam portion of the narrowed emission from the laser is directed through the wavelength calibration module and a beam portion is directed through the detection and control unit when the laser beam is scanned through the optical transition line of each of the species within the module. The detection and control unit is monitored and calibrated during the scanning.