We propose a turn-key in-situ gas sensor that can reliably perform continuous measurements on airborne, ship-based, or other mobile platforms. Specifically, we emphasize that the proposed system is compact, lightweight, power efficient, and therefore can be mounted on small to mid-sized un-crewed aircraft systems. The sensor features a small (centimeter scale) exposed beam path that allows ambient air circulation without active gas sampling. The proposed sensor is based on mid-infrared absorption spectroscopy using Pendar’s proprietary distributed feedback quantum cascade laser array (QCLA) technology. Our monolithically integrated chip-scale coherent source can withstand harsh operating conditions while offering superior wavelength and intensity stability compared to other broadband mid-infrared sources. Broadband spectral coverage (up to 500 cm-1) combined with high frequency resolution (~100 MHz) enable a multi-tasking sensor capable of detecting a multitude of gases including toxic industrial chemicals, chemical warfare agents, greenhouse gases, and volatile organic compounds. The laser source can rapidly tune over a large bandwidth to provide fast spectral measurements, enabling >100 Hz time response. Absorption measurements in the mid-infrared fingerprinting region ensures that a small pathlength is sufficient to reach uncertainty levels of <1% even when operating on moving platforms. By the end of Phase I, we will have built a prototype sensor and experimentally demonstrated that the sensor can reach targeted sensitivities under simulated flight conditions.
The proposed sensor can be directly adopted for airborne missions such as on NASA’s Airborne Science aircraft fleet, un-crewed aircraft systems and balloons to provide lower cost atmospheric gas measurements. The CO2 sensing capability can be utilized to augment the space-based measurements of CO2 dry air mole fraction under the OCO-2 project. The TEMPO project can also benefit from additional ozone and NO2 measurements.
We believe our proposed sensing solution can be adopted for chemical threat detection, which would be of interest to the Department of Homeland Security. The broadband sensing capability is also applicable to selective volatile organic compound detection in the air, which is of interest to markets targeting air quality measurements.