频域低相干光干涉的折射率三维重建系统

Three-dimensional Imaging of Optical Refractive Index by Low-coherence Interferometry in Fourier Frequency Domain

结合频域低相干光干涉及计算机断层重建技术,建立了光学折射率三维重建系统,系统主要包括宽带光源、光纤迈克尔逊干涉仪、光谱仪。由光谱仪采集探测光和参考光的干涉光谱,经傅里叶变换计算样品折射率的直线投影,利用滤波反投影算法进行折射率重建,得到样品的三维折射率分布。用塑料管对本方法进行了实验验证,该系统适合于对折射率均匀和非均匀的样品进行三维成像,该系统能检测到的折射率灵敏度约为0.01。本实验系统适合于作为本科生综合设计性物理实验项目。

Optical refractive index（ORI） is one of the most important physical parameters for the description of the characterization of optical material,and measurement of ORI is crucial for research and industrial applications. We demonstrate establish an experimental system for three-dimensional imaging of ORI by combining low-coherence interferometry in frequency domain and computed tomography. The experimental system mainly consists of a broadband light source,an optical fiber Michelson interferometer and a spectrometer. The interference spectra of the detection light and reference light are acquired with the spectrometer,and the parallel projection of optical refractive index is calculated from the acquired interference spectra by Fourier transformation. The three-dimensional distribution of refractive index is reconstructed by the filtered back-projection algorithm. We experimentally demonstrate this system by cross-sectional imaging of a plastic tube. The present system is suitable for three-dimensional imaging of samples with homogeneous and inhomogeneous ORI distributions,and the ORI sensitivity is 0. 01. The imaging system is suitable to be used as a synthetic and designing experiment in physical experiment teaching for undergraduates.