材料亚表面结构光热辐射检测实验

Photothermal Radiation Detection Experiment on Material Subsurface Structure

为开展光声光热技术实验教学,设计了材料亚表面结构光热辐射检测实验。应用层状材料在聚焦高斯光束激励下产生的三维热波的理论模型分析了光致热波的局域性、光热辐射信号随样品层厚度以及随背衬物质热学性质的变化规律。采用碳钢作为基体材料制作了一个含孤立横向盲孔的样品和一个含异质填充孔并带表面镀层的样品。采用半导体激光器、红外探测器等构建光热辐射检测实验系统。通过对样品进行光热辐射检测实验,验证了理论预期的检测能力:光热辐射信号对由泵浦光调制频率和材料热学参数决定的热扩散长度内的材料热学结构(材料界面位置、界面两边材料的热学性质等)敏感。

In order to carry out experimental teaching of photoacoustic and photothermal technology,a photothermal radiation detection experiment of material subsurface structure was designed. By using the theoretical model of the threedimensional heat wave generated by the layered material under the excitation of the focused Gaussian beam,the limitation of photothermal wave,the variation of photothermal radiation signal with the thickness of the sample layer and with the thermal properties of the backing material were analyzed. A sample with isolated lateral blind holes and a sample with heterogeneous filling holes and surface coating were made using carbon steel as the base material. The photothermal radiation detection experimental system was constructed by using a semiconductor laser,an infrared detector and other instruments. Through the photothermal radiation detection experiment on the samples,the detection ability was verified as theoretically expected: The photothermal radiation signal was sensitive to the thermal structure of the material (the position of the material interface,the thermal properties of the materials on both sides of the interface,etc.) within the thermal diffusion length which was determined by the pump light modulation frequency and the material thermal parameters.