Measurement of 14CO2 using off-axis integrated cavity output spectroscopy

14 C is one of the most important radioactive isotopes in the nuclear industry. Laser spectroscopy is being considered as a convenient and rapid method for 14 CO 2 analysis. Here, we demonstrate off-axis integrated cavity output spectroscopy (OA-ICOS) for monitoring 14 CO 2 . The experiment is performed at the 14 CO 2 absorption line at 2203.657 cm −1 in the mid-infrared region to obtain sufficient sensitivity. In the experiment, a resonator that consists of two mirrors with a reflectance of 99.6% is used. The linearity of OA-ICOS is investigated using CO 2 isotopologues’ signals. By applying the moving averaging filter, the interference noise is reduced, and the signal to noise ratio is improved by over 2.5 times.