Optical coherence tomography (OCT) is an interferometric technique based on optical coherent gating. In OCT, imaging contrast originates from the sample inhomogeneous scattering properties that are linearly dependent on the sample’s refractive indices. OCT offers axial resolution of 2‐15 μm and penetration depth around 2 mm. Since its invention in the late 1980s and early 1990s, OCT has experienced explosive growth in both technology and application.