Influence of working distance on microscale strain measurement under laser scanning microscope from moire fringes
Influence of working distance on microscale strain measurement under laser scanning microscope from moire fringes
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工作距离对激光扫描显微镜莫尔条纹微尺度应变测量的影响
DOI：
10.1117/12.2266697
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
S. Ogihara
中科院分区：
文献类型：
--
作者：
Q. Wang;Y. Takashita;S. Ri;H. Tsuda;R. Kitamura;S. Ogihara
本文利用扫描云纹法研究了激光扫描显微镜应变测量中工作距离的影响以及实现精确聚焦的方法。实验结果表明，在固定的WD下，应变测量具有良好的重复性。当WD变化范围在所用物镜透镜给定WD的0.9%以内时，可清楚地观察到扫描莫尔条纹。应变测量误差与WD差近似呈线性关系，最大应变误差接近700 με。幸运的是，2D莫尔条纹仅在非常窄的范围内是明显的，即，WD误差小于给定WD的0.1%，最大应变误差小于100 με。随着WD的变化，y方向的一维莫尔条纹、x和y方向的二维莫尔条纹以及x方向的一维莫尔条纹沿着交替清晰。因此，我们建议在每次聚焦过程中使用二维莫尔条纹进行微尺度应变测量，以减少WD变化引起的误差。此外，单次拍摄的2D莫尔图像可用于快速简单地测量两个方向上的应变分布，并且不需要像传统方式那样旋转样品或扫描线并扫描两次。
In this study, the influence of the working distance (WD) on strain measurement under a laser scanning microscope and a way to achieve precise focus were investigated by the scanning moiré method. Experimental results showed that the strain measurement has a good repeatability at a fixed WD. Scanning moiré fringes were clearly observable when the WD variation range was within 0.9% of the given WD of the used objective lens. The relationship of the measured strain error and the WD difference was approximately linear, and the greatest strain error was near 700 με. Fortunately, 2D moiré fringes were distinct only in a very narrow range, i.e., the WD difference was less than 0.1% of the given WD, and the greatest strain error was less than 100 με. 1D moiré fringes in the y direction, 2D moiré fringes in the both x and y directions, and 1D moiré fringes in thexdirection became distinct alternately along with the WD change. Consequently, we suggest to use 2D moiré fringes for microscale strain measurement in each focusing process to reduce the errors caused by the WD variation. Moreover, a single-shot 2D moiré image is useful to measure the strain distributions in both two directions quickly and simply, and there is no need to rotate the sample or scanning lines and scan twice as in the conventional way.