Coherence transfer function of the optical coherence tomography system

Optical coherence tomography system (OCT) had been analyzed theoretically as an imaging system upon the weak object approximation. The OCT system has been proved to behave as a linear shift invariance system and can be described precisely by a coherent transfer function (CTF). The derived longitudinal CTF shows that the system performs like a lowpass filter. High spatial frequency structure was detected because the spectrum of the object shifted a distance of 1/λ. The research will provide a theoretical basis for quantitatively analyzing the measured results of unknown structure and for increasing further the spatial resolution.