This paper reviews the state of the art of optical coherence tomography (OC
T), an interferometric imaging technique that provides cross-sectional view
s of the subsurface microstructure of biological tissue. Following a discus
sion of the basic theory of OCT, an overview of the issues involved in the
design of the main components of OCT systems is presented. The review concl
udes by introducing new imaging modes being developed to extract additional
diagnostic information.