| 摘要 |
PURPOSE:To compute the reflection function of a sound wave in the heterogeneous sound surface in a material by expanding a method for obtaining the reflection function from the Fourier transformation of V(Z) into a method for obtaining the reflection function at the reflection surface in the material. CONSTITUTION:In one step, a reflected signal from the inside of a material is received as a complex signal V(Z) 1. The signals are separated time wise and obtained by changing the distance between an acoustic lens and a material to be measured. The signal undergoes Fourier transformation 2. In the other step, a product 7 is obtained by multiplying the following functions: the square of the known pupil function of a sound lens 3; a first transmittance function wherein an angle, when an ultrasonic wave is transmitted from the surface of a material into the inside of the material, is a variable 4; a second transmittance function wherein an angle, when the ultrasonic wave is transmitted from the inside of the material to the outside of the material, is a variable 5; and a phase delay function wherein the incident angle of the ultrasonic wave, which is obtained from the sound speed of the main body of the material, is a variable. The result of the Fourier transformation is divided 8 by the product. Thus the reflecting function in the material is computed. |
