Fig. 1. Absorption spectrum of ethanol (Data from PNNL)

Fig. 2. Interference analysis about the absorption of IAO and the components

Fig. 3. Flow chart of data processing

Fig. 4. Schematic diagram of experimental setup

Fig. 5. Physical drawings of the experimental setup

Fig. 6. Signal comparison before and after baseline reconstruction

Fig. 7. Signal comparison of reference path and analysis path

Fig. 8. Ethanol absorption spectrum

Fig. 9. Allan variance