梯度折射率光纤探针的光学特征参数

解析梯度折射率(GRIN)光纤探针的光学特征参数,用于光学相干层析技术(OCT)探头超小型化的研究。在概述由单模光纤、无芯光纤和GRIN光纤镜头构成的GRIN光纤探针模型的基础上,定义GRIN光纤探针的工作距离和聚焦光斑尺寸等光学特征参数,并用高斯光束复参数矩阵变换的方法推导探针光学特征参数的数学表达式,提出了探针光学特征参数的验证方法。结果显示,当无芯光纤和GRIN光纤镜头长度分别为0.48mm和0.17mm时,理论计算的工作距离和聚焦光斑尺寸分别为1.05mm和28.2μm;实验测得的工作距离和聚焦光斑尺寸分别为1.0mm和28μm。理论计算与实测结果吻合,验证了GRIN光纤探针光学特征参数及其解析方法的有效性。

Optical Characteristic Parameters of Gradient-Index Fiber Probe

In order to investigate miniaturized probes for optical coherence tomography (OCT) imaging, the optical characteristic parameters of the gradient-index (GRIN) fiber probe are analyzed. The model of GRIN fiber probe is overviewed that consists of a single-mode fiber, a coreless fiber and a GRIN fiber len. The optical characteristic parameters (working distance, and focal spot size) of the probe are defined and solved by the complex beam parameter matrix transformation method. A method is proposed to validate the characteristic parameters experimentally. The results show that, setting the length of the coreless-fiber 0.48 mm and the length of the GRIN fiber len 0.17 mm respectively, the theoretical working distance and focal spot size are 1.05 mm and 28.2 μm accordingly. Given the same conditions, the experimental measured working distance and focal spot size are 1.0 mm and 28 μm respectively. Therefore, the theoretical values are in good agreement with the measured data, which validate the proposed optical characteristic parameters of GRIN fiber probe.