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Significant progress has been made in the study of optical coherence tomography (OCT) -a non-invasive, high resolution, and in vivo diagnostic method for medical imaging applications. In this paper, the principles of noise analyses for OCT systems have been described.Comparisons are made of signal-to-noise ratios for both balanced and unbalanced detection schemes under the ideal no-stray light situation as well as the non-ideal situation where residual reflections and scatterings are presented. Numerical examples of noise calculation accompanied by detailed comparison of the main characteristics of both time-domain and frequency-domain OCT systems are also presented. It is shown that a larger dynamic range can be achieved for a Fourier-domain OCT system even under the circumstances of high-speed image acquisition. The main results presented in this paper should be useful for the development of high performance OCT systems.

We analyze theoretically the dispersion of linearly polarized light propagating in a uniaxial anisotropic medium where multibeam interference is present. Explicit expressions of the group-delay dispersion for transmitting waves are derived for the simplest situation, and the effect of dispersion on pulse broadening is analyzed for a few selected cases. Our results reveal that at normal incidence and in the situation where the optic axis is parallel to the surface of birefringent plate (in the x-y plane), the dispersion of the refracted wave decreases with the extent of birefringence. In particular, the dispersion for the electric field parallel to the polarization direction of the incident light changes with the rotation angle between the optic axis and the polarization direction of the incident field, whereas the dispersion for the refracted field whose direction is vertical to the polarization of incident light is independent of this angle. For oblique incidence, dispersion varies substantially for different incident angles. In the situation where the optic axis is in the x-z plane at either normal or oblique incidence, the dispersion increases in a periodically oscillating manner as a function of the relative thickness of the birefringent plate.

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