| 摘要 |
PURPOSE:To enable the finding of a corresponding thickness by a method wherein a relationship is determined between a spatial reflection power of a layer structure the same as an object to be measured and a thickness of the object to be measured and an ultrasonic wave is radiated to an actual layer structure to measure a spatial reflection power thereof. CONSTITUTION:A V(Z) curve, namely, a relationship between a Z-axis distance and a reflection intensity of an ultrasonic wave can be determined by a theoretical analysis when the thickness of a layer structure of the surface of a base material and the base material and material of the layer structure are known. The V(Z) curve also can be determined by preparing a model member to measure it actually. Moreover, it is also possible to determine a spatial reflection power of a reflected wave by a Fourier analysis of the V(Z) curve. So, a relationship is determined between the thickness of the layer structure and the spatial reflection power for various material beforehand. Thus, the V(Z) curve for an object to be measured is determined by actual measurement and the Fourier analysis of the V(Z) curve is performed to determine a thickness corresponding to the spatial reflection power from the relationship between the spatial reflection power and the thickness of the layer structure obtained previously. |
