Microwave thermal imaging system for debonding detection of radar absorbing materials

In this paper, a microwave thermal imaging system (MTIS) has been presented for debonding detection of radar absorbing materials (RAMs). First, an overview of the mechanism underlying microwave heating and the fundamental principle of defect detection within RAMs is presented. Then, a multifunctional MTIS capable of performing both microwave lock-in thermography (MLIT) and long-pulse microwave thermography (LPMT) has been introduced, specifically tailored for the in situ inspection of RAMs. In addition, in this system, the detection area for a single scan is 90 * 90 mm2, with the emission source operating at a frequency of 5.8 GHz and boasting a maximum output power of 20 W. Next, based on MTIS, the above-mentioned two thermography techniques are applied to detect defects in RAMs. In addition, thermal contrast (Tc) and signal-to-noise ratio are introduced for the analysis of imaging results. Finally, the results show that LPMT can be used for preliminary detection of debonding defects in RAMs, while MLIT can be further used for detailed detection of debonding defects in RAMs. In addition, the minimum detection time of this MTIS is 45 s, and the minimum detectable defect aperture is 3 mm.