Gas laser for emitting light modulated at two different wavelengths and an arrangement incorporating the gas laser to detect a gaseous substance

US5544186A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventors

• Ralf Sauer · Overpelt, BE
• Wolfgang Rupp · Wertheim, DE
• Alexander Hinz · Sachsenheim, DE

Key dates

• Filing date: Jan 25, 1995
• Grant date: Aug 6, 1996
• Expiry date: Jan 25, 2015

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02A50/20
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A gas laser 1 such as a .sup.13 CO.sub.2 -laser emits at two different wavelengths (.lambda..sub.1, .lambda..sub.2) with a sine-shaped adjustment of a resonator mirror or a grating 13 such as a Littrow grating. The gas laser emits radiation at the two desired wavelengths (.lambda..sub.1, .lambda..sub.2) in two mutually adjacent intervals of the resonator length L because of a suitable dimensioning of the grating 13 with respect to grating structure and angle position, the outcoupling factor of the outcoupling mirror 12, the resonator length L and the composition of the gas of the laser. The laser emission is inhibited at the crossover between the two intervals and the sine-shaped modulation (for example with a piezo element) of the resonator length L is essentially symmetrical about this crossover. The invention is also directed to an arrangement for detecting a substance such as NH.sub.3 in a flue gas. This arrangement includes a two wavelengths laser light source 1, a modulation unit 14 and a reference detection unit D1; a transmission optic 2; a measuring path 3 which contains the substance to be detected; a receiving optic 4 and a measuring detector D2. An evaluation apparatus …