Fig. 1. Schematic diagram of metal thermal expansion

Fig. 2. Process flow diagram. (a) Cleaning;(b) location; (c) welding; (d) heat treatment

Fig. 3. Double quartz tube symmetrical structure. (a) Entity; (b) microscope figure; (c) spot welding

Fig. 4. Bare fiber tensile strength test results. (a) Wire stripper; (b) acetone

Fig. 5. The effects of discharge current and discharge time on tensile strength. (a) Discharge current; (b) discharge duration

Fig. 6. The effects of heat treatment temperature and cooling duration on tensile strength. (a) Heat treatment temperature; (b) cooling duration

Fig. 7. Metallized FBG microscope diagram. (a) Magnetron sputtering; (b) electroplating; (c) cross section

Fig. 8. Temperature sensing performance test system

Fig. 9. Calibration experiments

Fig. 10. Temperature response experiments. (a) Metallized FBG; (b) metallized stepped FBG