Attenuation of mirror image and enhancement of the signal-to-noise ratio in a Talbot bands optical coherence tomography system

Abstract

A Fourier domain optical coherence tomography setup is presented built around an optical configuration that exhibits Talbot bands. A low astigmatism spectrometer is used, employing a spherical mirror and a cylindrical lens between a diffraction grating and a linear CCD camera. To produce Talbot bands, the two interferometer beams--object and reference--are laterally shifted in respect to each other in their way toward the diffraction grating. This allows attenuation of mirror terms and optimization of the sensitivity profile. We evaluate the optimization of the sensitivity profile with depth, in respect to its overall strength and its position peak, which can be shifted toward a larger optical path difference in the interferometer. We demonstrate the efficiency of such a configuration at large depths by imaging a thick phantom and human skin in vivo for different values of the lateral distance between the two beams.