| 摘要 |
PURPOSE:To pass the high-frequency component and improve resolution by providing a SAW filter with the pass band near the center frequency of a wide frequency band. CONSTITUTION:The ultrasonic wave excited by a piezoelectric element 1 is fed to a tested material. The reflected wave from the tested material flows into the piezoelectric element 1, it is converted into a reflection signal and inputted to the first electrode section 3A of a SAW filter 3, and the reflection signal is converted into a surface elastic wave. The second electrode section 3B converts the incident surface elastic wave into an electric signal and inputs it to an amplifier 6. The amplifier 6 outputs it to a CPU processing section from an output section 10 via a receiver as the reflection signal. The SAW filter 3 passes the frequency in the preset high-frequency band near the center frequency or above it, and resolution can be improved. |
