Background

An advanced two-dimensional digital image correlation (2D-DIC) using active imaging and telecentric imaging has been proposed to overcome the problems of out-of-plane motion and ambient light variation.

Objective

Here, the technique is further improved by combining built-in coaxial illumination and telecentric fluorescent imaging to provide quality 2D-DIC measurement even in space-constrained scenarios.

Method

This improved 2D-DIC firstly excites the fluorescent speckles on the specimen surface using an ultraviolet light source through built-in coaxial illumination, and then employs a monochromatic telecentric imaging system to capture the images of the excited speckles. By tracking the movements of fluorescent speckles using DIC, full-field displacements and strains can be retrieved.

Result

For validation, the quality of speckle images captured by three different 2D-DIC systems was firstly evaluated, proving that the proposed fluorescent 2D-DIC can eliminate the specular reflections and acquire speckle images with the best quality. A uniaxial tensile test of an Al alloy specimen in an environmental chamber and thermal strain measurement of a polymethylmethacrylate sample in a water bath device were performed using the established system, further confirming the practicality of the proposed method.

Conclusions

With the improved performance, compactness, and ease of use, this fluorescent 2D-DIC is expected to be widely applied in future research.

中文翻译：

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荧光二维数字图像关联和内置同轴照明，在空间受限的情况下进行变形测量

背景

已经提出了使用主动成像和远心成像的高级二维数字图像相关性（2D-DIC），以克服平面外运动和环境光变化的问题。

目的

在此，通过将内置同轴照明和远心荧光成像相结合，即使在空间受限的情况下，也可以提供高质量的2D-DIC测量，从而进一步改进了该技术。

方法

这种改进的2D-DIC首先使用紫外线光源通过内置的同轴照明激发样本表面上的荧光斑点，然后采用单色远心成像系统捕获激发斑点的图像。通过使用DIC跟踪荧光斑点的运动，可以获取全场位移和应变。

结果

为了验证，首先评估了由三种不同的2D-DIC系统捕获的斑点图像的质量，证明了所提出的荧光2D-DIC可以消除镜面反射并获得最佳质量的斑点图像。使用建立的系统对环境室中的铝合金样品进行单轴拉伸试验，并在水浴装置中对聚甲基丙烯酸甲酯样品进行热应变测量，进一步证实了该方法的实用性。

结论

随着性能，紧凑性和易用性的提高，该荧光2D-DIC有望在未来的研究中得到广泛应用。