Simultaneous measurement of group and phase refractive indices and physical thickness of transparent plates with low coherence Fabry–Perot interferometry

We introduce a new method for simultaneously measuring group and phase refractive indices, the dispersion profile, and the physical thickness of transparent plates by using low coherent Fabry-Perot (FP) interferometry without using any mechanical scanning and sample rotation. A broadband infrared light source was used for a fiber-type FP interferometer, and the Fourier transform analysis on the measured interference spectra was performed to determine the refractive indices and thickness of BK7, quartz, and fused silica samples over its wavelength range. The accuracy of the physical thickness of the samples was obtained within an order of 1 μm scale, while that of both the group and the phase refractive indices was within the third decimal point.