| 摘要 |
PROBLEM TO BE SOLVED: To eliminate an internal reflection of an ultrasonic wave even when an acoustic impedance is changed in association with a change in the degree of a sound velocity control in a sound velocity control element in an ultrasonic probe having the sound velocity control element. SOLUTION: A sound velocity control element 50 has slope characteristics in which the acoustic impedance is continuously changed from an intermediate part to an organism side end. A matching layer 52 also has slope characteristics in which the acoustic impedance is changed from a non-organism side end to the organism side end. Even when the acoustic impedance of the control element 50 is changed, the acoustic impedance of the organism side end coincides with that of the layer 52. Accordingly, a reflection of the ultrasonic wave at its boundary part does not occur.
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