Optical coherence tomography using a tunable single-mode laser is investigated to clarify the effects of long coherence length and step-wise frequency changes.

A Fourier domain optical coherence tomography system for obtaining a two-dimensional image is constructed. Imaging characteristics of the OCT system in a transverse direction are experimentally investigated. Angle dependence of reflection intensity from a smooth surface is clearly observed and analyzed with consideration of spatial mode coupling to a fiber.