宝石晕彩效应的成因机理综述

综合分析不同宝石晕彩成因机理的最新研究成果,结果表明:所有具有晕彩效应的宝石,其晕彩成因大多与其内部存在的周期性层状结构有关,且层状结构厚度也限定在一定的变化范围内,同时层状结构的形成途径及其厚度变化范围因宝石种属的不同而异。从光学原理上详细探讨了光的干涉和衍射的形成条件,对比了光在不同晕彩宝石内产生干涉或衍射的理论条件与其实际情况,分析了宝石晕彩效应产生的两种光学模型:薄膜干涉式晕彩不仅要求宝石内部结构层的厚度必须在一定的纳米范围内,而且要求结构层由两相组分出溶而成,即其化学成分、折射率和结构层厚度形成三位一体;而光栅式衍射晕彩则仅要求结构层排列规则、边缘狭窄,能使入射光的振幅或位相或两者同时产生周期性空间调制即可。

Review on Origin of Iridescence in Gems

The latest researches on the origin of iridescence in the gems are synthetically reviewed.The results indicate that the iridescence is mostly related to the inner periodic lamellar structures in the gems and the thickness of the lamellar structures restricted within a certain scope,which are different from the variety of the gems.The optical principles of thin-film interference and diffraction are discussed in detail for analysing two optical models including thin-film interference and grating diffraction.The iridescence produced by the thin-film interference needs the thickness of lamellar structure within the certain nanometer range and the lamellar structure formed by exsolution of two phases,which the chemical compositions,refractive index and thickness of the lamellar structure are trinity.The iridescence produced by the grating diffraction just needs the lamellar structure arrayed regularly and the narrow edges which either amplitude or phase or both of incident light could produce periodic spatial modulation.