This paper reports on the experimental characterization by means of optical frequency-domain reflectometry of a White-type multipass gas cell used for trace gas spectroscopy. The fractional Lambertian reflections inevitably arising from the three high reflectivity mirrors of this multipass cell is precisely detected due to the high sensitivity of the reflectometer. Each bounce of light on the mirror surface generates backscattered light, which returns to the sensing system. Then, using the measured distribution of multiple back-reflections as a function of distance the position of the 3mm-thick CaF2 entrance window is clearly identified, thanks to the spatial resolution of 731μm. In addition, the physical distance between mirrors at both sides of the cavity is accurately assessed to be 40.72cm, delivering the exact optical path length of light inside the multipass cell of 30.9853m, which is an important parameter for improving the accuracy of the computation to retrieve the gas concentration from the measured light absorption spectrum.

This paper presents a novel low-cost & multi-gas non-dispersive infrared (NDIR) gas sensing platform with sub-ppm detection capabilities, targeting environmental monitoring of greenhouse gases. The design of the NDIR sensor combines highest-compactness and low-power consumption, with a unique multi-channel optical cell design, featuring the detection of up to three different gases, simultaneously. Our flexible sensor platform allows a customer specific selection of the target gases, making the sensor adaptable towards a variety gas monitoring scenarios. We verify our concept by the detection of multiple selective gases, such as CO 2 , CH 4 and H 2 O. The embedded calibration model includes temperature stabilization and addresses in real-time any cross-sensitivity between the NDIR gas sensing channels. This novel versatile platform offers both, high stability, and high precision (<0.1 ppm for CO2, <0.5 ppm for CH4). The sensor aims for medium to high volumes at reasonable costs, addressing the increasing need for cost-effective gas sensing solutions in the domain of environmental gas monitoring.

We report on a novel, cost-effective non-dispersive infrared (NDIR) multi-gas sensor aimed at environmental air pollution monitoring. The rugged design of the K96 sensor core combines highest compactness and low-power consumption with our unique multi-channel cell design, featuring the detection of up to three different gases simultaneously, including CO2, CH4, N2O, and H2O. Our sensing platform allows the selection of the target gases as well as the concentration ranges, thus providing highly customizable gas sensor systems targeting application-specific gas monitoring settings. The sensor core comes with an implemented calibration model, and can address in real time any cross-sensitivity between the NDIR gas-sensing channels. We provide an immensely versatile sensing system while ensuring high sensing stability combined with high precision (<0.1 ppm for both CO2 and N2O, <0.5 ppm for CH4). The K96 multi-gas sensor core offers a resilient sensor solution for the increasing demand of compact monitoring systems in the field of environmental monitoring at reasonable costs for medium-to-high volumes.