June 27, 2017 – CU researchers Dan Hesselius of the Integrated Remote and In Situ Sensing (IRISS) Initiative and Greg Rieker and Shalom Ruben of the CU Precision Laser Diagnostics Lab teamed with Kevin Cossel and Nathan Newbury’s team at NIST and DARPA to test their ability to track a drone with a comb laser, enabling precise measurement of trace gases. The results of this work were published in Volume 4, No. 7, in the scientific journal, Optica.
The paper outlines how this 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 infrared laser light. In combination with the DCS system and the unmanned aircraft system (UAS), we can perform accurate measurements revealing the horizontal and vertical spatial profile of these gases.
In the video above, Hesselius flies an X8 quadcopter fitted with a small retro-reflector mirror designed to reflect the optical frequency comb 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 the precision tracking system – the lab, led by Dr. Greg Rieker, was recently awarded a grant to track methane leaks using this techinology. 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.
In 2005, John L Hall of JILA was awarded the Nobel Prize in Physics for his work on the optical frequency comb technique used by this system.