NPL's Tunable Diode Laser Absorption Spectrometer (TDLAS) is a lightweight, near-infrared system that accurately measures trace atmospheric gases. The instrument is designed for field operation and is capable of detecting absorptions as small as one part in 10⁶ under the harshest of atmospheric conditions.

The instrument can be used to make high sensitivity measurements of a range of gases including methane, water vapour, carbon dioxide, hydrogen fluoride, hydrogen chloride and nitrous oxide.

Application

NPL's TDLAS is designed to be as flexible as possible and can be easily modified to make measurements under a range of operating conditions including:

• In the laboratory.
• At ground level.
• Balloon-borne.
• On board aircraft in the upper troposphere-lower stratosphere.
• Open-path measurements.
• High repetition rate measurements for eddy flux correlation and turbulence monitoring.
• Multiple species measurements with a number of lasers running simultaneously.

System specification

The basic specifications of an aircraft version of the TDLAS are given as an example of the instruments performance:

• Measurement precision: 4 ppb for methane.
• Measurement accuracy: +/- 5%.
• Response time: ½ Hz.
• Cross-sensitivity: the laser wavelengths used for the measurements are selected to minimise any cross-sensitivity effects. For measurements of methane made at 6067 cm^-1, the relative absorption of methane is 2x10⁵ times the absorption of carbon dioxide, and 1x10⁶ times the absorption of water vapour.

If you would like further information please contact us.