A miniaturized multipass cell for measurement of O2 concentration in vials based on TDLAS

•A miniaturized multipass cell (MMPC) was developed for enhancing the effective optical path within the vial.•The interference of ambient O2 was significantly suppressed due to the compact construction.•The beam pattern on the mirrors was calculated according to the analytical vector method.•The sensitivity with respect to the vial position was investigated for testing the robustness of the MMPC within a production chain.•The O2 concentration in the vial was measured by MMPC in combination with calibration-free.