CU researchers Dan Hesselius of the听Integrated Remote and In Situ Sensing (IRISS) Initiative听and Greg Rieker and Shalom Ruben听of the 听teamed with Kevin Cossel and Nathan Newbury's team at听听and DARPA to test their ability to track a drone with a comb laser, enabling precise measurement of trace gases.听The results of this work were published in , additional information provided by the
The paper outlines how this听new technique for the spatial mapping of atmospheric gases has been applied by using precise dual-comb spectroscopy to a retroreflector mounted on a multi-copter. Open path dual-frequency comb spectroscopy (DCS) has shown precise results in measuring pollutants, harmful gases, and greenhouse gases such as carbon dioxide (CO2), water vapor (H2O), and methane (CH4). The DCS system measures atmospheric absorption using thousands of individual frequencies with near听infrared laser light. In combination with the DCS system and the unmanned aircraft system (UAS), we can perform听accurate measurements revealing the horizontal and vertical spatial profile of these gases.
In the video below, Hesselius flies an X8 quadcopter fitted with a small retro-reflector mirror designed to reflect the听back to a base station. Using this reflection, the team is able to make very precise measurements of trace gases. The lower panels of the video show the measurements being made, while the upper left panel tracks the unmanned aircraft as it maneuvers.
The CU Precision Laser Diagnostics Lab helped develop听the precision tracking system -听the lab, lead by Dr. Greg Rieker,听was recently to track methane leaks using this techinology.听By utilizing UAS to reflect the comb, researches will be able to measure atmospheric trace gases in more environments, and with more accuracy, than ever before. 听
In 2005, John L Hall of听听was awarded the Nobel Prize in Physics for his work on the optical frequency comb technique听used by this system.