Simultaneous analysis of refractive index and physical thickness by Fourier domain optical coherence tomography

Fourier domain optical coherence tomography is explored as a tool for simultaneous refractive index and physical thickness measurement of layered samples. These parameters are obtained for a single layer from the component amplitudes and periods of sinusoidal functions fitted to the spectral interference, corresponding to the front and the back interfaces. A previously described phase-shifting technique is used to normalise the spectrogram, so that fitting is achieved without knowledge of the absolute source power. The effect of optical dispersion on the refractive index estimation is also investigated, confirming that this can significantly distort the measurement