Full-field automated photoelasticity by fourier polarimetry with three wavelengths.
Full-field automated photoelasticity by fourier polarimetry with three wavelengths.
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DOI：
10.1364/ao.40.000052
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发表时间：
2001
期刊：
影响因子：
1.9
通讯作者：
S. Berezhna;I. Berezhnyy;M. Takashi;A. Voloshin
中科院分区：
文献类型：
--
作者：
S. Berezhna;I. Berezhnyy;M. Takashi;A. Voloshin
寻找快速、精确和稳健的测试技术仍然是自动化全场光弹性中的一个重要问题。这里提出的基于偏振器样本分析器 (PSA) 的三波长偏振方法采用离散傅立叶分析和光谱内容展开算法，可完全自动、简单、快速且准确地确定两种光弹性参数。实验数据的傅立叶分析和三波长方法减少了噪声的影响，并有效地解决了等色和等斜图区域中精度差的问题。由于任何偏振技术都会产生相应三角函数主范围内的相位值，因此数据处理的最后一步是相位展开。由于包裹相位图的良好质量以及每个点都是独立处理的，我们建议的三波长解包裹算法表现出高水平的鲁棒性。与其他一些 PSA 三波长技术不同，这里给出的算法完全解决了相位展开问题。具体来说，它将实验获得的反余弦型相位图直接转换为全相位值分布，跳过生成反正切型斜坡相位图的步骤，并采用其他展开例程进行最终数据处理。新技术的精度已通过 Babinet-Soleil 补偿器进行了估计。直径压缩盘和石英板的测试实验证明，该技术可以用于精确测定等斜角和相对延迟，即使后者值很大。
The search for fast, precise, and robust testing techniques remains an important problem in automated full-field photoelasticity. The polarizer-sample-analyzer (PSA)-based three-wavelength polarimetric method presented here employs discrete Fourier analysis and a spectral content unwrapping algorithm to provide completely automatic, simple, fast, and accurate determination of both photoelastic parameters. Fourier analysis of experimental data and a three-wavelength approach reduce the effect of noise and efficiently cope with poor accuracy in regions of both isochromatic and isoclinic maps. Because any polarimetric technique yields the phase value in the principal range of the corresponding trigonometric function, the final step in data processing is phase unwrapping. Because of the good quality of the wrapped phase map and because each point is processed independently, our suggested three-wavelength unwrapping algorithm exhibits a high level of robustness. Unlike some other PSA three-wavelength techniques, the given algorithm here solves the problem of phase unwrapping completely. Specifically, it converts experimentally obtained arccosine-type phase maps directly into full phase value distributions, skipping the step of generating an arctangent-type ramped phase map and resorting to other unwrapping routines for final data processing. The accuracy of the new technique has been estimated with a Babinet-Soleil compensator. Test experiments with the disk in diametric compression and a quartz plate have proved that the technique can be used for precise determination of the isoclinic angle and relative retardation, even for large values of the latter.