AQTIVE - Active quantitative thermography using innovative vertical emitting lasers

主动热像仪已经成为检测和表征缺陷和材料不均匀的一种杰出的无损检测方法。有两种技术几乎是独家使用的：具有闪光类能量输入的脉冲热成像用于检测近表面缺陷，以及具有周期性能量输入的锁定热成像用于检测更深层次的缺陷。由于测试是以平面方式进行的，因此可以快速获得结果并以图像表示。测试部件内部的定量重建极其复杂，因此通常被省略。或者，光热测试提供层厚测量和材料表征，但只能通过缓慢的逐点扫描。该项目的两个主要目标是：将不同的热像和光热材料测试和表征技术统一到一个平面和定量的测量系统中，以及验证该方法比以前的方法更快、更精确、更通用。其中，我们预计它将允许对目前几乎无法测试的未涂层金属进行测试。通过将一种新型的高功率激光器(垂直腔面发射激光器阵列)集成到现代红外热像系统中，建立了定量和高精度测量的仪器要求。这种组合产生了成功的决定性参数：辐照度、调制带宽、相位稳定性和光谱纯度。由此产生的潜力将在该项目中进行实验研究，同时更新的理论概念将被开发出来。通过考虑不同的材料、塑料和金属，涵盖了广泛的应用。这种方法的优势将通过实际应用得到验证，例如材料表征、涂层厚度测量和断裂测试。最后，将开发和评估热波整形的新概念，以提高检测灵敏度。如果成功，该项目将有助于充分挖掘平面热成像的潜力。它可能会提供一种范式转变，从分离的光热和热成像技术向更快、更精确的统一、定量的测量和测试方法转变。

Active thermography has been a distinguished non-destructive testing method for the detection and characterization of defects and material inhomogeneities. There are two techniques that are employed almost exclusively: pulse thermography with flash-like energy input for detection of near-surface flaws and lockin thermography with periodic energy input for detection of deeper defects. Since testing is performed in a planar fashion, results are available fast and are represented as images. Quantitative reconstruction of the inside of the tested parts is extremely complex and therefore usually omitted. Alternatively, photothermal testing provides layer thickness measurements and material characterization, but only via slow point-by-point scanning. This separation into different applications is mostly due to the lack of sufficiently fast, phase stable, high-power and spectrally suitable energy sources and infrared thermography systems.The two main objectives pursued within the project are: the unification of the different thermographic and photothermal material testing and characterization techniques into one planar and quantitative measuring system, as well as the verification that this method is faster, more precise and more versatile than previous ones. Among others, we expect it to allow for testing of currently barely testable uncoated metals. The instrumental requirements for quantitative and high-precision measurements are established by integrating a novel high-power laser (vertical-cavity surface-emitting laser array) into modern infrared thermography systems. This combination yields the decisive parameters for success: Irradiance, modulation bandwidth, phase stability and spectral purity. The resulting potential is to be investigated experimentally within the project, while updated theoretical concepts are to be developed. A broad range of applications is covered by considering the different materials plastics and metals. The advantages of this approach will be verified using practical applications, such as material characterization, coating thickness measurement and fracture testing. Eventually, novel concepts for thermal wave shaping are to be developed and evaluated in order to enhance detection sensitivity.In case of success the project will help tapping the full potential of planar thermography. It will possibly provide a paradigm shift from the separated photothermal and thermography techniques to a unified, quantitative measuring and testing method that is faster and more precise.