Presby H M, Marcuse D
Appl Opt. 1974 Dec 1;13(12):2882-5. doi: 10.1364/AO.13.002882.
A new method to determine the index of refraction in combination with the diameter of the cores of stepindex optical fibers and preforms is presented. The technique is based on an analysis of the backscattered light when a beam from a cw laser impinges transversely upon the fiber or preform. A geometrical-optics analysis shows that, under appropriate assumptions, a combination of the refractive indexes and the radii of the core and cladding can be determined from unique characteristics of the backscattered radiation pattern. The theory is compared to experimental observations with excellent agreement.
提出了一种结合阶跃折射率光纤及预制棒纤芯直径来确定折射率的新方法。该技术基于对连续波激光束横向照射光纤或预制棒时背向散射光的分析。几何光学分析表明，在适当假设下，可根据背向散射辐射图样的独特特性确定纤芯和包层的折射率与半径的组合。理论与实验观测结果进行了比较，二者吻合良好。
