| 摘要 |
PURPOSE:To improve response property and enable transmission reception of a wide range of ultrasonic signals without reducing sensitivity by selecting a thickness of the acoustic-matching layer of ultrasonic probes equipped with a lambda/4 or thinner reflector depending on the thickness of the reflector. CONSTITUTION:The piezoelectric device includes a piezoelectric material with an acoustic impedance of 2.5X10<6>-15X10<6> kg/m<2>s and a reflector with a thickness of lambda2/4 or less where lambda2 is the wavelength of the sound in the said reflector at a half of the frequency of the free resonance frequency of the piezoelectric device. The acoustic-matching layer includes a material with an acoustic impedance within 1.6X10<6>-4X10<6> kg/m<2>s and whose thickness lies in a range of lambda3/8-28lambda3/120. The acoustic matching layer 4 with a thickness lambda3/4 markedly improves the response characteristic R and the sensitivity a little when the thickness of the reflector falls within the range E-E' of 8lambda2/120-30lambda2/120.
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