Low-coherence tomography technique in biological tissues

Low coherence optical tomography (OCT) is a novel technique with high resolution for rapid, noninvasive imaging in living biological tissues. With this technique, a thin 'optical section' within a thick biological specimen can be obtained. Using a combination of the principles of low-coherence interferometry and confocal microscopy, OCT can provide micron-scale tomographic imaging of internal tissue microstructures. In OCT, enhanced optical sectioning performance in biological tissues (highly scattering media) is achieved through high detection sensitivity and high contrast rejection of out-of-focus light. In this paper, basic principle and recent advances in optical coherence tomography are described. The emphasis is to analyze some key problems in OCT setup. Light attenuation and scanning system are studied in detail. A theoretical model for low-coherence optical tomography in highly scattering media (biological tissues) is given. The authors will show that OCT images may be significantly affected by multiple scattering associated with the refractive index inhomogeneities found in scattering media such as biological tissues. At last, a conclusion suggests that OCT is a very promising technique for clinical application because of its simple theory and low cost.