ABSTRACT

The coating of materials has grown to an important treatment for improving functionality and appearance of components. A decisive factor for a reliable and consistent performance in its field of application is the layer thickness of coated materials. Consequently, monitoring and controlling the thickness, especially the homogeneity of the coating, represent relevant tasks on a large scope. Active thermography has been established as a method for quality monitoring, but excitation sources for conventional lock-in thermography are either very expensive or relatively inert. Commonly used excitation sources for pulse thermography have a high responsiveness, but a lower signal-to-noise-ratio (SNR) usually confines the result. In this paper, a novel approach is presented where the sample is periodically excited with consecutive pulses and submitted to a lock-in evaluation. This so-called pulsed lock-in thermography offers a less expensive and reproducible way for non-destructive testing and has the potential for large-area measurement of the thickness of coatings.

摘要

材料涂层已发展成为改善部件功能和外观的重要处理方法。在其应用领域中获得可靠和一致性能的决定性因素是涂层材料的层厚。因此，监测和控制厚度，尤其是涂层的均匀性，代表了大范围的相关任务。主动热成像已被确立为一种质量监测方法，但传统锁定热成像的激发源要么非常昂贵，要么相对惰性。脉冲热成像常用的激发源具有高响应性，但较低的信噪比 (SNR) 通常会限制结果。在本文中，提出了一种新颖的方法，其中样品被连续脉冲周期性地激发并提交给锁定评估。这种所谓的脉冲锁定热成像技术为无损检测提供了一种成本较低且可重复的方法，并具有大面积测量涂层厚度的潜力。