Determination of Thickness of an Inaccessible Thin Film under a Multilayered System from Natural Frequencies  

作　　者：周昌智 李明轩 毛捷 王小民 

机构地区：[1]Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190

出　　处：《Chinese Physics Letters》2008年第4期1336-1339,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant No 10474113. The authors thank Professor Ying Chong-Fu for his helpful discussion.

摘　　要：We investigate the relationship between natural frequencies of a multilayered system of different elastic materials and the thickness of the undermost thin film. The natural frequencies are numerically calculated from the reflection coefficient of a sample system of ＂steel-epoxy resin-aluminium-thin polymer＂ with normal incidence. Strain energy ratio is defined and calculated to give the physics explanation why some frequencies are sensitive to thickness of the thin film in certain range. Experiments of three specimens indicate that the measured natural frequencies agree well with the theoretical ones. It is found in our experiments that the ratio of the lowest film thickness to wavelength is about 1/5. The average relative errors for the inverted polymer film thicknesses are found to be 11.8%, -4.8% and -1.3%, respectively.We investigate the relationship between natural frequencies of a multilayered system of different elastic materials and the thickness of the undermost thin film. The natural frequencies are numerically calculated from the reflection coefficient of a sample system of ＂steel-epoxy resin-aluminium-thin polymer＂ with normal incidence. Strain energy ratio is defined and calculated to give the physics explanation why some frequencies are sensitive to thickness of the thin film in certain range. Experiments of three specimens indicate that the measured natural frequencies agree well with the theoretical ones. It is found in our experiments that the ratio of the lowest film thickness to wavelength is about 1/5. The average relative errors for the inverted polymer film thicknesses are found to be 11.8%, -4.8% and -1.3%, respectively.

关 键 词：supernova explosion proto-neutron star shock wave 

分 类 号：TN75[电子电信—电路与系统]