MWGS-1: Multi-Wavelength Gas Sensor

Description

Physical Sciences Inc. (PSI) has developed a new instrument for the laser-based sensing of gases. This instrument is based on recent advances in two areas: diode-pumped solid-state lasers, which produce high average powers from a compact device, and engineered non-linear optical materials such as periodically poled lithium niobate (PPLN), which can efficiently convert the fixed wavelength of a solid-state laser into one or more tunable output wavelengths. Using a unique three-zone design for the PPLN crystal, near-infrared radiation from a pump laser is converted into radiation at three different wavelengths in the mid-infrared. These wavelengths are chosen to provide good atmospheric transmission along with selective detection of the target species. The wavelengths can be tuned by changing the temperature of the PPLN crystal.

Basic Features

• Simple, rugged design consisting of one pump laser and one non-linear optical crystal
• Continuous-wave, or quasi-continuous wave, output with 1 to 10 W total average power in the mid-infrared
• Fully automated measurement
• Standard 19-in. rack mounted controller and readout units

Applications

• Remote detection of atmospheric trace gases such as methane, carbon monoxide, carbon dioxide, and sulfur dioxide for studies of atmospheric chemistry, geochemistry, and volcanology
• Detection of fugitive emissions from industrial facilities

Specifications

• Non-intrusive remote measurement
• 10 part-per-million-meter detection sensitivity
• Response time 100 ms
• Standoff range 5 to 50 meters

Wavelength Conversion Scheme. The PPLN crystal is divided into three zones, each with a different quasi-phase-matching period (Λi). Starting from a fixed near-infrared pump wavelength (λpump), each zone produces a different mid-infrared output wavelength (λi).

Schematic diagram showing the key components of the Multi-Wavelength Gas Sensor.

DIAL/LIDAR Systems Publications Environmental Monitoring Publications DIAL/LIDAR Systems Presentations		Photonics Enterprise LIDAR Nonlinear Optical Materials Spectroscopic Sensing

Douglas Bamford Physical Sciences Inc. 2110 Omega Road/Suite D San Ramon, CA 94583 Telephone: (925) 743-1110 Fax: (925) 743-1117 bamford@psicorp.com