介绍了调制加热阶段的一维热波导热方程。为了减少图像序列采集数量，针对相位法红外热成像检测提出了获取热波信号相位信息的方法，即相关检测算法。利用噪声信号与参考信号不相关的原理，有效地提取微弱被测信号。通过对同一组图像序列的处理，将其与4点平均算法比较，证实该算法采集信息少，具有较高检测精度。同时也验证了相位信息对样品表面非均匀性不敏感，使得相位法红外热像技术在无损检测中有广泛应用。

Onedimensional heat conduction equation of thermal wave during modulated heating was described. A method, correlation algorithm, was promoted to detect phase information in lockin thermography nondestructive testing in order to reduce sample images. Using the principle of the reference signal being uncorrelated to the measured signal, the latter could be extracted easily. Compared with averaging fourpoint algorithm, correlation algorithm was shown to have better precision and need less information. The experiment also confirmed that the phase was less affected by surface nonuniformity. So the phase thermography technique was expected to have wide applications in NDT field.