中文摘要：

报道了一种利用激光光声背激发技术测量薄膜材料热扩散率的原理与实验方法，通过测量背激发光声信号的相位，得到了背激发光声信号的相位随频率、薄膜厚度变化规律，进而得到了不同薄膜厚度下材料的热扩散率。结果表明当薄膜材料的厚度减少到微米级时，热扩散率表现出对厚度尺寸效应的依赖性，此时需用微观热量输运理论进行分析。

英文摘要：

The principle and experimental methods of detecting film materials by laser photoacoustic backing exiting technique are reported. The phase of back exciting photoacoustic signal can be measured. The varying regular pattern of phase with frequency and film thickness are obtained. Thermal diffuaivities are obtained at different film s hickness. For BaTiO3 film materials, the result indicates that thermal diffusivity shows clear size effect when film thickness is micrometer size. The experiment result can be analysis by microscopic heat transport.