Researchers at the University of Texas, Austin, have developed a method of optical coherence tomography (OCT) for two- and three-dimensional subsurface scanning that requires no moving parts. Prospective applications include medical imaging and semiconductor inspection.
The OCT technology—currently under development as an optical alternative for medical imaging and nondestructive-testing applications performed by CT, magnetic resonance (MR), and ultrasound imaging—also relies on a tomographic process. This effect is achieved in most OCT schemes by varying the optical path length of the reference arm in a Michelson interferometer structure and observing interference fringes when that path length falls within one coherence length of a reflective location within the material under study. The sample arm of the interferometer illuminates the material under study using a broadband light source. The detection mechanism is based on cross correlating the reference- and sample-arm signals.