Fig. 1. Schematic diagram of sensor probe

Fig. 2. Schematic diagram of optical coupling for inclined receiving optical fiber

Fig. 3. Variation in output power with axial distance under different radiuses of transmitting optical fiber

Fig. 4. Variation in output power with axial distance under different numerical apertures of transmitting optical fiber

Fig. 5. Variation in output power with axial distance under different radiuses of receiving optical fiber

Fig. 6. Variation in output power with axial distance under different optical fiber spacings

Fig. 7. Variation in output power with axial distance under different tilt angles of receiving optical fiber

Fig. 8. Fiber optic sensor. (a) Receiving optical fiber; (b) transmitting optical fiber; (c) 3D printing model; (d) sensor probe

Fig. 9. Experimental setup

Fig. 10. Penicillium citrinum images. (a) Surface morphology of Penicillium citrinum on pine wood; (b) 196.3 μm; (c) 256.1 μm; (d) 292.5 μm; (e) 373.6 μm; (f) 406.1 μm

Fig. 11. Spectral information of Penicillium citrinum on pine wood. (a) Characteristic absorption spectrum; (b) relationship between absorbance and mold height at wavelength of 261 nm

Fig. 12. Trichoderma longibrachiatum images. (a) Surface morphologyof Trichoderma longibrachiatum on pine wood; (b) 86.3 μm; (c) 136.2 μm; (d) 221.6 μm; (e) 281.2 μm; (f) 496.1 μm

Fig. 13. Spectral information of Trichoderma longibrachiatum on pine wood. (a) Characteristic absorption spectrum; (b) relationship between absorbance and mold height at wavelength of 272 nm

Fig. 14. Growth of Trichoderma longibrachiatum on pine wood after soaking in NaCl solution with different relative mass fractions. (a) No mold infection; (b) 0; (c) 2%; (d) 4%; (e) 6%; (f) 8%

Fig. 15. Spectral information of Trichoderma longibrachiatum after soaking in NaCl solution with different relative mass fractions