Fig. 1. Schematic diagram of pressure measurement by direct absorption spectrometry

Fig. 2. Diagram of experimental system of barometric pressure measurement by direct absorption spectroscopy

Fig. 3. Simulation results of negative pressure absorbance curves

Fig. 4. Simulation results of positive pressure absorbance curves

Fig. 5. Curves of transmitted light signal

Fig. 6. Absorbance curves

Fig. 7. Lorentz function fitting results diagram of absorbance curve

Fig. 8. Curve fitting results of ΔA，A₁，A under different pressure points