Dual-Probe Simultaneous Measurements Of Refractive Index And Thickness With Spectral-Domain Low Coherence Interferometry

An optical interferometric system for the simultaneous measurements of physical thickness and refractive group index is implemented. The proposed system is based on a spectral-domain optical low coherence interferometry with two sample probes facing to each other. The two-probe approach enables simultaneous measurements of thickness and group index of a transparent sample. The average measurement errors were similar to 0.112 % in the physical thickness and similar to 0.035 % in the group index, respectively.