一、引言截面折射率分布是优质光纤材料制备工艺中必须控制的一个最重要的参数,它对于所拉制成光纤的光传输性能有决定性的影响。因此,国内外的许多科技工作者在截面折射率测量方面做了大量的工作。根据所使用方法的原理,大体可分为:反射法、近场图象法、散射法和干涉法等四类。我们使用的方法属于显微干涉法的一种。干涉法无论在原理上或在方法上都比较成熟,所使用的设备较少,准确度和精确度也比较高。但是,它要求样品的两面具有高度 I. INTRODUCTION The cross-section refractive index distribution is one of the most important parameters that must be controlled in the preparation process of high-quality optical fiber materials. It has a decisive influence on the optical transmission properties of optical fibers drawn into optical fibers. Therefore, many scientists at home and abroad have done a great deal of work on the measurement of cross-section refractive index. According to the principle of the method used, can be roughly divided into four categories: reflection method, near field image method, scattering method and interference method. The method we use is one of the methods of microscopic interference. The interference method is mature in principle or method, uses less equipment, and has higher accuracy and precision. However, it requires that both sides of the sample have a height