Application Cases

Experiment Name: Performance Study of Tapered Cone Ultrasonic Sensors

Test Purpose: The performance of FBG ultrasonic sensors is primarily evaluated by three key indicators: frequency resolution characteristics, frequency response characteristics, and linearity characteristics. Since ultrasonic cleaners exhibit overall vibration with varying amplitudes at different points on the device, and the double tapered cone sensor requires two surfaces to contact the measured object, this may affect the validation of sensor performance. Therefore, a signal generator connected to a piezoelectric ceramic plate is used to generate ultrasonic signals at a single point to verify the performance of the double tapered cone sensor.

Test Equipment: ATA-2021B High-Voltage Amplifier, signal generator, oscilloscope, piezoelectric ceramic plate, laptop, double tapered cone ultrasonic sensor, photodetector, etc.

Experimental Process:

Figure 1: FBG narrowband light source demodulation system

An FBG narrowband light source demodulation system was set up as shown in Figure 1. The high-sensitivity narrowband light source demodulation hardware system mainly consists of two parts: the receiving part and the excitation part. The excitation part includes a signal generator, Aigtek high-voltage amplifier, oscilloscope, piezoelectric ceramic plate, and laptop. The receiving part consists of a tunable narrow-linewidth laser, optical circulator, double tapered cone ultrasonic sensor, and photodetector.

The working principle of the excitation part is as follows: The excitation signal generated by the signal generator is amplified by the ATA-2021B high-voltage amplifier, which then drives the PZT to generate ultrasonic waves. These waves are vertically coupled and propagate into the structure under test.

Figure 2: Aigtek ATA-2021B High-Voltage Amplifier

The main function of the power amplifier is to amplify the weak voltage signal from the signal generator, thereby increasing the vibration amplitude of the PZT. The experiment uses the Aigtek ATA-2021B high-voltage amplifier (Figure 2), a single-channel high-voltage amplifier capable of amplifying AC and DC signals. Its maximum output voltage range is 200 Vp-p, adjustable according to the output rail. The DC bias voltage is adjustable in three steps, with a continuous variation range of up to ±160 V, meeting the requirements for asymmetric signal output and driving high-voltage loads.

Experimental Results:

The positions of the excitation source and the sensor were fixed during the experiment to study the frequency resolution characteristics and frequency response characteristics of the double tapered cone ultrasonic sensor.

Figure 3: FBG detection of ultra-high-frequency sinusoidal signals (a) 4 MHz (b) 6 MHz

The double tapered cone FBG ultrasonic sensor successfully detected ultra-high-frequency sinusoidal signals at 4 MHz and 6 MHz, as shown in Figure 3. The detected signals showed minimal distortion, indicating the sensor's inherent capability to detect ultra-high-frequency signals. By optimizing the sensor structure or demodulation system, the detection bandwidth of the sensor can be effectively increased.

Figure 4: Sinusoidal signals at 20–130 kHz detected by the double tapered cone FBG sensor

To test the response amplitude of the sensor to signals of different frequencies, the double tapered cone ultrasonic sensor was used to detect sinusoidal ultrasonic signals in the frequency range of 20–130 kHz. The test results are shown in Figure 4.

High-Voltage Amplifier Recommendation: ATA-2021B

Figure: ATA-2021B High-Voltage Amplifier Specifications

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