Fig. 1. Working principle of terahertz time-domain spectroscopy system

Fig. 2. Sample with multi-layer bonded structure. (a) Design drawing; (b) physical drawing

Fig. 3. THz waveform detection drawing

Fig. 4. Diagram of energy integral value. (a) Gray scale of integral value; (b) statistical graph of probability of integral value

Fig. 5. Refractive index during curing period

Fig. 6. Extinction coefficient during curing period

Fig. 7. Probability distribution of energy integral value of upper adhesive layer in each period

Fig. 8. Probability distribution of energy integral value of lower adhesive layer in each period

Fig. 9. Characteristic value of energy integral. (a) Upper adhesive layer; (b) lower adhesive layer

Fig. 10. Flight time distribution

Fig. 11. Curve of time-of-flight characteristic value