| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ultrasonic probe which can receive a reflected wave from a sample with high sensitivity. SOLUTION: An ultrasonic wave oscillated from a piezoelectric membrane 3 is converged through a lens plane 7a and directed through a medium to a sample and then reflected on the surface thereof. The reflected wave is received by a piezoelectric membrane 5 through the lens plane 7a and the body of an acoustic lens 7 and a corresponding output voltage is then amplified by a receiver through electrodes 4, 6 before being fed to an image processor providing the information of specimen. The thickness t5 of piezoelectric membrane 5 is set thicker than the thickness t3 of piezoelectric membrane 3 and the difference t5 -t3 is set to match the frequency drop caused by the attenuation of ultrasonic wave oscillated from the piezoelectric membrane 3, reflected on the sample and received by the piezoelectric membrane 5. With such a structure, reflected wavefrom a sample can be received with high sensitivity even if the central frequency thereof drops slightly when it is received by the piezoelectric membrane 5 and highly accurate information concerning the sample can be obtained. |
