Surface Thermometry Using Laser-Induced Second Harmonic Generation

本文对激光诱导二次谐波（SHG）测量热金属表面温度的适用性进行了实验研究。本研究的直接目标是获得足够的数据，以消除SHG作为候选诊断或进一步引起对SHG测温技术发展的兴趣。在这项研究中，主要感兴趣的表面将是沉积在钽或陶瓷基板上的铂（粗糙和抛光表面）。将执行三个独立的研究任务。首先，将使用在电炉中加热的样品，在300至1000 K的表面温度范围内寻找SHG信号与温度的可重复校准图，（希望）证明相对SHG信号与表面粗糙度无关。接下来，将在高温炉或燃烧环境中扩展到1800k的校准图。最后，对SHG测量技术的动态响应进行了研究。提出的研究方向的最终目标是为燃烧、传热和材料加工领域的实际高温应用开发SHG测温技术，特别是在制造设备的在线控制方面的应用。

An experimental study for assessment of the applicability of laser- induced second harmonic generation (SHG) for measurement of temperatures of hot metallic surfaces will be carried out. The immediate goal of this research is to obtain sufficient data to either eliminate SHG as a candidate diagnostic or create further interest in the development of SHG thermometry. In this study, the main surface of interest will be platinum (rough and polished surfaces) deposited on a tantalum or ceramic substrate. Three separate research tasks will be performmed. First, a repeatable calibration plot of SHG signal versus temperature at surface temperatures from 300 to 1000 K will be sought using samples heated in an electric furnace, with (hopefully) demonstration that the relative SHG signal is independent of surface roughness. Next, the calibration plot will be extended to 1800 K in either a high- temperature furnace or a combustion environment. Finally, dynamic response of the SHG measurement technique will be investigated. The ultimate goal of the proposed research direction is development of SHG thermometry for practical high-temperature applications in the fields of combustion, heat transfer, and materials processing, with particular application to on-line control of manufacturing facilities.