News

Name of experiment：high precision underwater acoustic velocity measurement method based on femtosecond laser frequency comb

Research direction：a new femtosecond laser method for sea water sound velocity measurement to ensure the traceability of measurement accuracy

Content of experiment：the ultrasonic transducer is driven by an amplifier to realize the underwater acoustro-optic modulation experiment, and then realize the accurate measurement of sound velocity .

Purpose of experiment：the ultrasonic transducer is driven by a power amplifier, and the regular and symmetrical sine wave is sent out by the transducer, and the regular pulse optical envelope signal is obtained indirectly.

Experimental process：

The trigger frequency period of ultrasonic transducer is adjusted by signal generator. ATA122D power amplifier was connected to the output end, the amplifier gain was adjusted to 26dB, Rin was set to 1M, Rout was set to 50 Ω, and output was switched on to start the experiment. Figure 1 shows the signal source working with the amplifier, and figure 2 shows the sinusoidal waveform of the ultrasonic transducer on an oscilloscope.

Result of experiment：

Driven by amplifier, sound pulse waveform with regular period can be obtained. Figure 1 is the acoustic pulse sine waveform of ultrasonic transducer driven by the power amplifier. Figure 2 is the Interference envelope diagram of ultrasonic modulated femtosecond laser frequency comb. Figure 3 is the envelope peak diagram after normalization of Hilbert transform. It can be seen obviously that the sine wave signal sent by the ultrasonic transducer driven by the amplifier is symmetrical and complete, so that the measurement results can meet the expected requirements. In the later acoustic velocity processing, the corresponding peak value of the signal envelope can be found accurately, and the accurate results can be obtained.

Figure 1: acoustic pulse sine waveform of ultrasonic transducer driven by the power amplifier

Figure 2: the Interference envelope diagram of ultrasonic modulated femtosecond laser frequency comb.

Figure 3: the envelope peak diagram after normalization of Hilbert transform

The role of the amplifier in this experiment：

The ultrasonic transducer (500KHZ) is driven to ensure that the ultrasonic wave can output a complete sinusoidal waveform, and can freely adjust the gain amplitude, so as to freely switch the strength of the ultrasonic signal under different light intensity, to achieve the experimental purpose.