Frequency modulated thermal wave imaging (FMTWI) has been considered as one of the promising non-destructive testing and evaluation approach due to its merits such as economical, safe, fast, sensitive and high depth resolvability. The present work provides a novel analytical solution for FMTWI using one-dimensional heat conduction equation with adiabatic (Neumann) boundary conditions. The temperature gradient over the glass fiber reinforced polymer specimen has been analyzed and validated with a commercially available three dimensional mathematical finite element model to retrieve the quantitative information regarding the subsurface defects. The efficiency of the proposed method is highlighted using matched filter based approach for a frequency modulated imposed heat flux. The depth resolvability of the proposed method has been studied from the obtained correlation lag and the time domain phase obtained for FMTWI technique.

调频热波成像（FMTWI）由于其经济，安全，快速，灵敏和高深度可分辨性等优点而被认为是有前途的无损检测和评估方法之一。本工作提供了一种使用绝热（Neumann）边界条件的一维热传导方程对FMTWI进行分析的新方法。玻璃纤维增​​强的聚合物样品上的温度梯度已经过分析，并使用可商购的三维数学有限元模型进行了验证，以检索有关次表面缺陷的定量信息。对于基于频率调制的施加热通量，使用基于匹配滤波器的方法突出了所提出方法的效率。