A dual-frequency ultrasonic transducer and a spontaneous and self-receiving measurement method for high-order harmonics

Abstract

The invention discloses a dual-frequency ultrasonic transducer which is used for nonlinear ultrasonic measurement of a sample. The ultrasonic transducer comprises a transmitting wafer (1), an insulating layer (2), a receiving wafer (3) and a protective layer (4), wherein the insulating layer (2) is used for isolating electrical signals between the transmitting wafer (1) and the receiving wafer (3); the protective layer (4) is located at the other side of the receiving wafer (3); and the receiving wafer (3) is located on the central axis of the transmitting wafer (1). In addition, the inventionalso provides a self-transmitting self-receiving measurement method for higher harmonic waves based on the dual-frequency ultrasonic transducer. The method can realize self-transmitting self-receiving nonlinear ultrasonic detection and can ensure a sufficient signal-to-noise ratio.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic detection, and in particular relates to a dual-frequency ultrasonic transducer and a self-generating and self-receiving measuring method of high-order harmonics. Background technique [0002] An ultrasonic transducer is a device that converts other forms of energy into sound energy. In the traditional non-destructive testing, the nonlinear ultrasonic signal is measured by the penetration method, that is, a fundamental frequency transducer (center frequency is f) is required as the emission source, and a high frequency transducer is placed on the other side of the sample as the transmission source. receiver. Generally speaking, the frequency band of the transmitting transducer is narrow to avoid introducing nonlinear high-order harmonic signals, while the center frequency of the receiving transducer is at n times the frequency of the transmitting transducer (the center frequency is n*f, n=2,3,...

AI Technical Summary

Problems solved by technology

However, in actual operation, it is often impossible to contact both sides of the sample at the same time, or it is difficult to keep the transmitting and receiving transducers on the same axis, resulting in the inability to smoothly collect high-order harmonic signals

[0003] Although the use of traditional broadband transducers can achieve spontaneous and self-receiving measurements, on the one hand, due to its frequency band limitation, generally only the second harmonic can be measured, and higher harmonics cannot be measured; on the other hand, due to the transducer The bandwidth covers the second harmonic frequency, which will introduce a second harmonic component into the transmitted signal, and cannot be distinguished from the second harmonic generated by the sample, which will bring large system noise

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