Dispersion, spot size and speckle noise effects in fourier-domain optical coherence tomography

In this work we present a rigorous analysis of the propagation of light wave through the sample in Fourier-domain optical coherence tomography (FD - OCT). We considered a sample with four layers having refractive index dispersion. We assumed that light wave is a Gaussian beam propagating through the sample. We consider the radius of the beam under different circumstances. Beam radius accounts for diffraction and lateral resolution. We varied different parameters like focal length, depth of focus, tilt of the sample and center wavelength and calculated beam radius under variation of these parameters. Then we considered the interferogram under dispersion, dispersion free and dispersion with speckle Rayleigh noise. We calculated resolution and shift of position of the main lobe with regard to the position in the case of dispersion free and noise free condition. We plotted family of curves for different layer interfaces.