从频域角度运用相干传递函数阐明了热波成像系统的成像特征，用热波成像方法测量了样品内部结构缺陷的低频信息．研究表明缩小泵浦光斑在一定程度上有利于提高空间分辨率．系统的通频带随着缺陷趋近于表层而增大，从而解释了热波成像对亚表面结构极为敏感． From the perspective of frequency domain, the imaging features of the thermal wave imaging system are illustrated by using the coherent transfer function. The low frequency information of structural defects in the sample is measured by the thermal wave imaging method. Research shows that reducing the pump spot to a certain extent, help to improve the spatial resolution. The passband of the system increases as the defect approaches the surface, thus explaining that thermal wave imaging is extremely sensitive to subsurface structures.