Fig. 1. THz-TDS system. (a) Light path of transmissive THz-TDS system; (b) z3 reflective imaging system

Fig. 2. Aging test setup and aging samples. (a) Aging test chamber; (b) aging samples

Fig. 3. Defect samples

Fig. 4. THz waveforms of samples with different aging time. (a) Time-domain waveform; (b) frequency-domain waveform

Fig. 5. Reflective indices of samples with different aging time

Fig. 6. Absorption coefficients of samples with different aging time

Fig. 7. Reflective imaging results of samples. (a) Sample with scratch; (b) sample with delamination; (c) sample with metal ring