Senseair has built and trimmed a long path length Multipass cell with a light distance of almost 18 meters. This equipment has been shipped to the researchers at CSEM in Neuchatel, Switzerland for verification and test. The next step in the development of optics is to replace the mirrors with new ones having higher reflectivity in the mid-IR spectral range. Moreover, Senseair will arrange for convenient interface with the laser beam input, and beam exit towards the spectromet