模斑尺寸 w_0是表征单模光纤的一个重要参量。远场变换孔径法的优点在于,它测定的是二维远场功率,因而对光源和检测器的要求较低,从 w_0与波长λ的关系可求出等效阶跃(ESI)光纤参数如芯半径α,相对折射半差△和截止波长λ_c。测量过程和数据处理全部由程控单色仪,步进马达驱动孔径转盘和计算机自动完成。 The speckle size w_0 is an important parameter for characterizing single mode fiber. The advantage of Far Field Transform Aperture method is that it measures the two-dimensional far-field power, so the requirements on the light source and the detector are low. The equivalent step (ESI) fiber parameters can be obtained from the relationship of w_0 and wavelength λ Core radius α, relative refractive half-difference △ and cutoff wavelength λ_c. Measurement process and data processing all by program-controlled monochromator, stepper motor driven aperture dial and computer automatically.