Measurement of group refractive index wavelength dependence using a low-coherence tandem interferometer

Abstract

A technique for the measurement of the group refractive index wavelength dependence of optical materials using a low-coherence tandem interferometer and a spectrometer is proposed. Four channeled spectra resulting from interferences of light beams from different pairs of optical paths are used for the calculation of optical path differences. The group refractive index wavelength dependence is calculated from these optical path differences generated from the sample under measurement. No a priori information of the geometric thickness of a sample is required. The wavelength dependence of the group refractive index of the samples BK7 parallel plate of 5.200 and $10.025\text{\hspace{0.17em} mm}$ from 675 to $850\text{\hspace{0.17em} nm}$ is experimentally measured with an accuracy of the order of ${10}^{-5}$ and a repeatability of the order of ${10}^{-9}$.

© 2006 Optical Society of America