The use of circularly polarized light for biometry, identification and estimation of mass of coccoliths
The use of circularly polarized light for biometry, identification and estimation of mass of coccoliths
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DOI：
10.1016/j.marmicro.2014.08.007
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发表时间：
2014-12-01
影响因子：
1.9
通讯作者：
Sierro, Francisco J.
中科院分区：
文献类型：
--
作者：
Fuertes, Miguel-Angel;Flores, Jose-Abel;Sierro, Francisco J.
最常用的工具，观察和识别球石和其他钙质超微化石是一个透射光显微镜配备了交叉偏光镜。这种显微镜可以很容易地修改，以产生圆偏振光（CPL），而不是线偏振光，这可以克服线偏振光的一些缺点。在圆偏振光下，任何方向上的小球状体都不会消光，因此可以立即看到整个标本，径向球状体不再显示交叉偏振光典型的伪消光十字，因此它们的外观不会随方向而变化，并且它们的形态的某些方面更容易观察。最后，结合圆偏振光和倾斜照明获得的显微镜聚光灯意味着颗石亮度是较少依赖于倾斜的晶体c轴比一般假设，使质量估计的基础上集成的亮度比可能更可靠的预期。因此，这种照明方法在钙质超微化石的研究中具有广泛的应用，包括生物统计学，分类鉴定，以及计算各种分类群的颗石大小和质量。在这里，我们描述这种方法结合一个新的计算机程序的开发，用于分析在圆偏振光下捕获的图像。然后，我们重点将这种技术应用于计算各种分类群的颗石大小和质量，并将结果与之前的研究进行比较。(C)2014爱思唯尔有限公司版权所有。
The most commonly used tool for observing and identifying coccoliths and other calcareous nannofossils is a transmitted light microscope equipped with crossed polarizers. Such microscopes can readily be modified to produce circularly polarized light (CPL) instead of linearly polarized light, and this can overcome some disadvantages of linearly polarized light. With circularly polarized light there is no extinction of small coccoliths at any orientation, so the whole specimen can be seen at once and radial coccoliths no longer show the pseudo-extinction crosses typical of crossed polarized light, so their appearance does not vary with orientation and some aspects of their morphology are much easier to observe. Finally the combination of circularly polarized light and the oblique illumination obtained with the microscope condenser means that coccolith brightness is less dependent on inclination of the crystal c-axis than is generally assumed and so that mass estimates based on integrated brightness are more reliable than might be expected. This illumination method thus has a wide range of applications in the study of calcareous nannofossils, including biometry, taxonomic identification, and calculations of coccolith size and mass for a wide range of taxa. Here we describe this method combined with the development of a new computer program for analysis of images captured under circularly polarized light. We then focus on applying this technique to calculations of coccolith size and mass of various taxa, comparing results with previous studies. (C) 2014 Elsevier B.V. All rights reserved.