Laser wavelength and bandwidth monitor

US6597462B2 · kind B2 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Matthias Kramer · Bottrop, DE
• Marcus Serwazi · Gleichen, DE

Key dates

• Filing date: Feb 22, 2001
• Grant date: Jul 22, 2003
• Expiry date: May 12, 2021

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/1392
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A first method for determining the relative wavelength shift of a laser beam away from a known reference line, such as an absorption line of a gas in an opto-galvanic cell or a reference line of reference laser uses a monitor etalon. The FSR of the etalon used to calculate the wavelength shift is determined based on a calculated gap spacing between the etalon plates, or etalon constant. The gap spacing is determined based on a fit to measured values of wavelength deviations of the FSR as a function of the relative wavelength shift. The FSR used to calculate the wavelength shift is also based on the wavelength shift itself. A second method for measuring the absolute bandwidth and spectral purity of a tunable laser beam uses an opto-galvanic or absorption cell. The laser beam is directed to interact with a gas in the cell that undergoes an optical transition within the spectral tuning range of the laser. The beam is tuned through the optical transition line of the gas in the cell, and the opto-galvanic or absorption spectrum of the line is measured. The measured bandwidth and spectral purity are convoluted or broadened by the bandwidth of the laser beam used in the measurement. The b…