A dynamic photoelastic ultrasound imaging method and system

Abstract

The invention relates to a dynamic photoelastic ultrasonic imaging method and system. The system comprises a synchronous time-delay system, an ultrasonic emission system, an ultrasonic energy transducer, a parallel light beam generation unit, a polarizer, a sample placing point, a polarization analyzer, an imaging lens and a collection unit, wherein the sample placing point is positioned between the polarizer and the polarization analyzer and used to place an observation sample; the parallel light beam generation unit generates parallel light beams in uniform light-intensity distribution; thepolarizer and the polarization analyzer process the parallel light beams to obtain a light pulse signal of high signal to noise ratio; the imaging lens carries out imaging on the received light pulsesignal; and the collection unit realizes ultrasonic imaging by collecting light pulse signals passing the imaging lens for multiple times and overlapping the signals. Thus, the system sensitivity canbe improved substantially, a better ultrasonic imaging effect is realized, and a weak ultrasonic field in a solid body is observed.

Description

technical field [0001] The present application relates to the field of ultrasonic technology, in particular to imaging and systems of ultrasonic sound fields in solids, and in particular to a dynamic photoelastic ultrasonic imaging method and system. Background technique [0002] Quantitative measurement of ultrasonic sound field in solids is of great significance for studying the propagation and scattering of ultrasonic waves in solids and developing new technologies for ultrasonic nondestructive testing. [0003] In "Scattering of Ultrasound in Solids" published by National Defense Industry Press in 1994, a dynamic laser photoelastic ultrasonic imaging device was disclosed, and a method for measuring the ultrasonic sound field in transparent solids was discussed. The light source of the system is a pulsed laser, which has the advantages of high energy and short pulse compared with LED light source. The laser beam emitted by the pulsed laser has a single-mode or multi-mode...

AI Technical Summary

Problems solved by technology

After the laser beam is directly expanded, it still has the original spatial distribution, so the sample cannot be uniformly exposed, which affects the imaging quality and quantitative measurement accuracy of the ultrasound.

[0004] Existing laser-based dynamic photoelastic ultrasonic imaging systems generally use fundamental transverse mode lasers with Gaussian distribution, which do not shape the spatial distribution of beam energy, so the sample cannot be uniformly exposed, resulting in brighter central parts of the image, resulting in measurement errors

In addition, the pixels in the center of the image are prone to saturation, which is not conducive to quantitative measurement

If the Gaussian beam is shaped by a flat-hat light shaper, a more uniform beam can be obtained, but the edge energy jitter is large, which is not conducive to imaging and quantitative measurement, and the cost is very high

[0005] In addition, the polarizers and analyzers of existing commercial or self-developed photoelastic systems generally use resin polarizers, which have a low extinction ratio (not exceeding 1000:1), resulting in large noise in the received optical signal exist, and are difficult to remove by image processing methods, so the signal-to-noise ratio and sensitivity of the system are low, and weak ultrasonic signals cannot be observed

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