Surface Thermometry Using Laser-Induced Second Harmonic Generation

为评估激光诱导二次谐波(SHG)在测量高温金属表面温度方面的适用性，将进行一项实验研究。这项研究的直接目标是获得足够的数据，以消除SHG作为候选诊断或引起对SHG测温发展的进一步兴趣。在这项研究中，主要感兴趣的表面将是沉积在钽或陶瓷衬底上的铂(粗糙和抛光表面)。将执行三项独立的研究任务。首先，将使用在电炉中加热的样品来寻找表面温度在300-1000K范围内倍频信号随温度变化的可重复校准图，并(希望)证明相对倍频信号与表面粗糙度无关。接下来，无论是在高温炉中还是在燃烧环境中，校准曲线都将扩展到1800K。最后，对倍频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发展SHG测温技术，用于燃烧、换热和材料加工领域的实际高温应用，特别是应用于制造设施的在线控制。

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.