DIAL – Differential Absorption LIDAR

The use of LIDAR to make atmospheric measurements dates back to the 60’s. This would have to make Differential Absorption LiDAR, or DIAL one of the first LIDAR applications. Today most of the use of DIAL is for scientific research – investigating holes in the ozone layer and the increase in greenhouse gases, for example. NOAA, NASA and Environment Canada are actively involved with DIAL studies.

The basic principle with DIAL is that the gas you are trying to detect will have a known absorption “signature” at certain wavelengths. By sending out 2 wavelengths, one that is known to be absorbed by the gas of interest, and a second that is close to the first, but is not absorbed. The second can then be used as the baseline for comparison, and the concentration of the gas of interest can be determined. The lasers can be tuned to different wavelength signatures, depending on the application.

As mentioned in the previous blog post, I came across a session being offered at the upcoming GITA 2009 conference that will describe a system being used to detect leaks in natural gas pipelines, and explore areas for coal bed methane. From a recent article in Geospatial Solutions the system being used was developed by the ITT Corporation’s Space System Division. Nicknamed ANGEL – Airborne Natural Gas Emission LiDAR, the sensor is being combined with a medium format digital mapping camera system to provide a very cost effective pipeline monitoring solution.

I am hoping to attend GITA and will report back.

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