Optical coherence tomography (OCT) is an emerging optical imaging modality for biomedical research and clinical medicine.
OCT can perform high resolution, cross-sectional tomographic imaging in materials and biological systems by measuring the
echo time delay and magnitude of backreflected or backscattered light [1]. In medical applications, OCT has the advantage
that imaging can be performed
in situ and in real time, without the need to remove and process specimens as in conventional excisional biopsy and histopathology.
OCT can achieve axial image resolutions of 1 to 15 μm; one to two orders of magnitude higher than standard ultrasound imaging.
The image resolution in OCT is determined by the coherence length of the light source and is inversely proportional to its
bandwidth. Femtosecond lasers can generate extremely broad bandwidths and have enabled major advances in ultrahigh-resolution
OCT imaging. This chapter provides an overview of OCT technology and ultrahigh-resolution OCT imaging using femtosecond lasers.
OCT was first demonstrated in 1991 [1]. Imaging was performed in vitro in the human retina and in atherosclerotic plaque as examples of imaging in transparent, weakly scattering media and in highly
scattering media. In vivo OCT imaging of the human retina was demonstrated in 1993 [2, 3] and clinical studies in ophthalmology began in 1995 [4–6].
Since that time, OCT has emerged as an active area of research.