中文摘要：

经典的Stokes理论认为非偏振光叠加仍为非偏振光。以高斯一谢尔模光束为示例，表明光场在自由传播的过程中情况并非总是如此。并以此为例，展示Stokes理论的可叠加性原理在描述光场传播过程中的本地行为和全局行为上是有区别的。作为应用示例，讨论了一个与大气和生物组织相关的散射势获取的问题。

英文摘要：

Two independent unpolarized light beams can sum up to be one unpolarized light beam based on the classical Stokes theory. However, it＇s demonstrated that its global validation needs a preliminary requirement. The work was carried out with an example of a Gaussian-Shell beam. An applicable hint was given with the determination of scattering potentials in atmospheric and biological experiments.