Long open-path laser dispersion sensing
28 Feb 2018



The Laser Spectroscopy Group develop Laser Dispersion Spectroscopy (LDS) based instruments that derive concentration using the phase of light.

​​​​​Launch optics for the long open-path CH4 CLaDS sensor. Visible laser alignment..

​​​​​Launch optics for the long open-path CH4 CLaDS sensor. Visible laser alignment.

Credit: STFC RAL Space

​Laser Dispersion Spectroscopy (LDS) is a new gas sensing technique that applies a novel approach to tuneable diode laser spectroscopy. Common techniques depend on measuring detected intensity to derive concentration. This significantly impacts measurements in “dirty" environments where detected intensity of the transmitted light is bound to fluctuate. The group develops LDS-based instrument that derives concentration using the phase of light. This makes it highly immune to intensity fluctuations received at the photodetector. The instrument enables precise, real time measurements of trace gas molecules in demanding environments. Furthermore, compared to absorption techniques, the analyser can measure gas concentrations within a very wide dynamic range (typically about five to six orders of magnitude), meaning for example from parts per billion all the way to sub percent concentrations without the requirement for dilution.

In a long open-path, multi-direction configuration, coupled with a retroreflector arrays, and anemometer, the LDS analyser is capable of measuring gas concentrations associated with large area sources, and locating and quantifying of point source emissions within said area.

For more information please contact: RAL Space Enquiries​​