Four-dimensional image formation theory of optical coherence tomography

Abstract: We construct an accurate imaging theory for optical coherence tomography/microscopy (OCT/OCM) without approximations to calculate precise optical resolution and imaging characteristics. Our theory represents a broadband light source using a four-dimensional (4D) pupil function with a dimension for light frequency (reciprocal of wavelength) as the fourth axis in 4D frequency space. Consequently, 4D space-time representation is required in real space, connected to the 4D frequency space by a 4D Fourier transform. Our theory provides insight into a peculiar image formation in OCT/OCM, particularly when an apparatus has a high numerical aperture (NA) optical system to handle aberrations and dispersions simultaneously.