A compact QCL spectrometer for mobile, high-precision methane sensing aboard drones

In 2020 researchers from Empa - Swiss Federal Laboratories for Materials Science and Technology, Switzerland published in Atmospheric Measurement Techniques (EGU) an article where they describe a QCL spectrometer containing photodetector produced by VIGO Photonics, which is situated on drone!

Scientists focused on creating a mobile sensing platform for high-precision atmospheric methane measurements. The system had to meet the assumptions: small, light, energy efficient, high-precision, and working outdoors. Authors used two recent innovations: a novel segmented circular multipass cell design that provided 10 m (65 reflections!) optical path length at a total mass of less than 200 g, and a power-efficient, low-noise, intermittent continuous-wave laser driving approach. They decided to use a 7.7 um spectral region (typically used for methane is 3.3 um) due to ease of use distributed feedback quantum cascade
lasers (DFB-QCL) and 7.7 um region is at the edge of the atmospheric window, i.e. interfering absorption due to water vapor is considerably weaker – what is extremely important because of the work outdoor. The best option for this spectral region is a multijunction HgCdTe (MCT) photodiode – PVM-2TE-8 made by VIGO Photonics. It is characterized by high detectivity in 7-9 um because of its specific construction.

The open-path system has an overall weight of 750 g (2.1 kg including battery) and an electrical power consumption of 18W. The instrument is characterized by a precision of 1 ppbv CH4 at 1 Hz. Such drones can be used to measure emissions from the oil- and natural gas infrastructure facilities. W
We are proud that our detectors can support environmental protection using innovative methods like drones.

Link to the article