Grup d'Òptica, Physics Department, Universitat Autònoma de Barcelona, Bellaterra, Spain.
LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, Palaiseau, France.
PLoS One. 2019 Mar 14;14(3):e0213909. doi: 10.1371/journal.pone.0213909. eCollection 2019.
Optical methods, as fluorescence microscopy or hyperspectral imaging, are commonly used for plants visualization and characterization. Another powerful collection of optical techniques is the so-called polarimetry, widely used to enhance image contrast in multiple applications. In the botanical applications framework, in spite of some works have already highlighted the depolarizing print that plant structures left on input polarized beams, the potential of polarimetric methods has not been properly exploited. In fact, among the few works dealing with polarization and plants, most of them study light scattered by plants using the Degree of Polarization (DoP) indicator. Other more powerful depolarization metrics are nowadays neglected. In this context, we highlight the potential of different depolarization metrics obtained using the Mueller matrix (MM) measurement: the Depolarization Index and the Indices of Polarimetric Purity. We perform a qualitative and quantitative comparison between DoP- and MM-based images by studying a particular plant, the Hedera maroccana. We show how Mueller-based metrics are generally more suitable in terms of contrast than DoP-based measurements. The potential of polarimetric measurements in the study of plants is highlighted in this work, suggesting they can be applied to the characterization of plants, plant taxonomy, water stress in plants, and other botanical studies.
光学方法，如荧光显微镜或高光谱成像，常用于植物可视化和特征描述。另一种强大的光学技术集合是所谓的偏振测量法，广泛用于在多种应用中增强图像对比度。在植物学应用框架中，尽管已经有一些工作强调了植物结构对输入偏振光束产生的去偏打印，但偏振测量法的潜力尚未得到充分利用。事实上，在少数涉及偏振和植物的工作中，大多数研究了使用偏振度（DoP）指标的植物散射光。其他更强大的去偏化指标如今被忽视了。在这种情况下，我们强调了使用 Mueller 矩阵（MM）测量获得的不同去偏化指标的潜力：去偏化指数和偏振纯度指数。我们通过研究一种特殊的植物——摩洛哥常春藤（Hedera maroccana），对 DoP 与 MM 图像进行了定性和定量比较。我们表明，在对比度方面，基于 Mueller 的指标通常比基于 DoP 的测量更适用。这项工作强调了偏振测量在植物研究中的潜力，表明它们可应用于植物特征描述、植物分类学、植物水分胁迫以及其他植物学研究。
