Piezoelectric detection device based on LSAW (laser surface acoustic wave) locating of PVDF (Polyvinylidene Fluoride) piezoelectric thin film

Abstract

The invention relates to precise orientation and measurement of ultrasonic propagation. The propagation direction of a surface acoustic wave is precisely located, and simultaneously, surface acoustic wave signals at different positions are detected to improve measurement precision. The technical scheme adopted by the invention is as follows: a piezoelectric detection device based on LSAW (laser surface acoustic wave) locating of a PVDF (Polyvinylidene Fluoride) piezoelectric thin film is composed of two parts, i.e. a PVDF piezoelectric sensor and piezoelectric probes, wherein the PVDF piezoelectric sensor and the piezoelectric probes are movably interconnected, the PVDF piezoelectric sensor is divided into four quadrants which are separated from one another, two electrodes are led out from each quadrant, and finally, four paths of piezoelectric signals in total, which are sent out by upper electrodes of the quadrants, are respectively transmitted to a high speed wideband oscillograph; the four piezoelectric probes are distributed in a mode of four quadrants, but are in two parts separated from each other, every two quadrants are organically integrated, and the two integrated probes are arranged in parallel to a laser exciting line and come into tight contact with the PVDF piezoelectric thin film. The piezoelectric detection device disclosed by the invention is mainly applied to the mechanical property measurement of materials.

Description

technical field [0001] The invention relates to the precise orientation of ultrasonic propagation and the evaluation of the mechanical properties of materials, in particular to a piezoelectric detection device based on PVDF piezoelectric film LSAW positioning. Background technique [0002] In recent years, the measurement of nanomechanical properties of materials by laser ultrasonic technology has attracted more and more attention. In the non-optical detection of laser ultrasonic, it is a common method to use polyvinylidene fluoride PVDF piezoelectric film sensors to receive ultrasonic signals. method and has been widely used. [0003] In the journal "Journal of Testing Technology", Volume 21, Issue 3 published in 2007, Yagang, Shen Zhonghua, and Lu Jian published an article titled "Experimental Method for Laser Surface Acoustic Wave Detection Using PVDF". The piezoelectric probe used is composed of PVDF film, knife, metal fixing block, high-frequency cable and preamplifier...

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Problems solved by technology

[0005] In order to detect and measure more accurately, it must be ensured that the probe's knife is placed perpendicular to the propagation direction of the ultrasound. Moreover, in order to overcome the influence of environmental factors on the measurement results, it should be required to simultaneously measure the signals from two different positions at the same time. In the method adopted in the first literature, although a precision electric displacement platform is used to ensure good straightness, the micro-knife is only placed roughly perpendicular to the propagation direction of the surface acoustic wave during the test process, which cannot be corrected. Accurate positioning and precise measurement of the propagation direction of ultrasound

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