Application of power amplifier in ultrasonic resonance spectrum measurement of piezoelectric

Name of experiment: ultrasonic resonance spectrum measurement of piezoelectric samples

Research direction：characteristic of piezoelectric material

Content of experiment: measure the ultrasonic resonance spectra of piezoelectric samples under the conditions of plated electrode and non-plated electrode

Purpose of experiment：

By testing the ultrasonic resonance spectrum of piezoelectric samples and identifying several resonant modes, the elastic and piezoelectric coefficients of piezoelectric materials can be inverted

Test equipment: lock-in amplifier (Stanford SR865A)+ power amplifier (Aigtek ATA-122D)+ ultrasonic transducer

Experimental process：

The computer controls the lock-in amplifier to output a sweep signal of 50khz-2mhz. The signal is amplified by the power amplifier and used as the excitation signal of the ultrasonic transducer to drive the sample to produce high-frequency vibration. The vibration is received by the receiving ultrasonic transducer and returned to the lock-in amplifier for processing. Then the ultrasonic resonance spectrum of the sample is output, from which several resonant frequencies of the sample can be identified. On this basis, the elasticity and piezoelectric coefficient of the piezoelectric sample can be inverted.

Result of experiment:

Figure (a) is the ultrasonic resonance spectrum of the unplated electrode piezoelectric ceramic cuboid sample tested by the ultrasonic resonance spectrum test system.

Figure (b) is the ultrasonic resonance spectrum of electroplated piezoelectric ceramic cuboid sample obtained by test. Each peak corresponds to a resonant frequency, and the relative error between the elastic coefficient and ultrasonic pulse is less than 3% by using several resonant frequencies read from the spectrum.

The role of the amplifier in this experiment:

The sweep signal output by the lock-in amplifier is amplified as the excitation signal of the ultrasonic transducer to drive the piezoelectric sample to produce ultrasonic vibration and complete the test experiment.

Reasons for choosing this amplifier:

The bandwidth and amplification just meet the requirements, and the test results are stable.

Experimental process

The computer controls the lock-in amplifier to output a sweep signal of 50khz-2mhz. The signal is amplified by the power amplifier and used as the excitation signal of the ultrasonic transducer to drive the sample to produce high-frequency vibration. The vibration is received by the receiving ultrasonic transducer and returned to the lock-in amplifier for processing. Then the ultrasonic resonance spectrum of the sample is output, from which several resonant frequencies of the sample can be identified. On this basis, the elasticity and piezoelectric coefficient of the piezoelectric sample can be inverted.

Result of experiment

Figure (a) is the ultrasonic resonance spectrum of the unplated electrode piezoelectric ceramic cuboid sample tested by the ultrasonic resonance spectrum test system. Figure (b) is the ultrasonic resonance spectrum of electroplated piezoelectric ceramic cuboid sample obtained by test. Each peak corresponds to a resonant frequency, and the relative error between the elastic coefficient and ultrasonic pulse is less than 3% by using several resonant frequencies read from the spectrum.