Fig. 1. Experimental set-up for oxygen detection in nano-porous ceramics based on TDLAS

Fig. 2. Measured second harmonic absorption signal of oxygen in ceramic sample with a porosity of 70%, a diameter of 100 mm, and a thickness of 15 mm

Fig. 3. Optimization of detection position. (a) Detection geometry; (b) distribution of laser shooting position; (c) spatial distribution of measured L_eq

Fig. 4. L_eqand K_eq of ceramic samples with same porosity and different thicknesses. (a) L_eq; (b) K_eq

Fig. 5. L_eq and K_eq of ceramic samples with the same thickness as a function of porosity. (a) K_eq;(b) L_eq

Fig. 6. Experimental results of ceramic samples with 70% porosity and different thickness. (a) Oxygen transport characteristics; (b) relationship between gas transmission time constant and thickness

Fig. 7. Water vapor transport in 20 mm thickness of ceramic samples with 45% and 70% porosity