| 摘要 |
PURPOSE:To evaluate the internal constituent distribution of a sample by a method wherein the transmission time of an ultrasonic wave reaching each detection point is measured and the transmission time of the ultrasonic wave passing through each region of a model is measured and the propagation time of the ultrasonic wave passing through each region of the model is calculated. CONSTITUTION:In such a case that an endless strip plate having an equal thickness is a unidimensional object wherein constituent distribution is unhomogenous only in an X-axis direction being a plate thickness direction, when the left end of a drawing is irradiated with a laser pulse having a fine spot diameter, an ultrasonic wave is generated from the irradiated point by thermoelastic effect and received at a place Sm by a receiver to show the transmission time GAMMAm of the ultrasonic wave by formula I along a propagation path Lm. Herein, the length of a fine path is set to dl, m=1, 2...N. Next, the thickness of the strip plate is divided into (N) layers so that the receiving place Sm is necessarily contained in different layers and, when it is supposed that a constituent is uniform in the respective layers, GAMMAm is given by formula II (wherein reversal Vi is the reciprocal of the propagation speed in each layer and K is the number of the layers contained in Lm). By this method, the constituent of each region can be evaluated from the propagation speed of the ultrasonic wave passing through each region of the model. |
