optical coherence tomography (oct) is a method of acquiring and processing optical signals. it assists to obtain 3d images with resolution of micron grade through galvo-scanning optical scattering medium like biological tissues. adopting the principle of optical spectral interference, oct technology provides micron grade resolution images of living tissues by photo taking with near-ir and selecting longer wavelength that travels to a certain depth of scanned medium. oct has a multiple commercial application including artwork conservation, diagnostic machinery, and achieving detailed images on retina in ophthalmology, etc.
by reflecting light on tissues and providing cross-section images, oct generates images upon surface and subsurface of a substance that is transparent or opaque. extremely high resolution can be achieved by the advantage of short wave light. the main advantages is that with its superior qualities, high-resolution of micron grade imaging can be made quickly and directly on living tissues, without ionizing radiation and the necessity of sample preparation.
ophthalmology application: as a new optical diagnostic technique, oct is used in noncontact and noninvasive tomography on microscope structure of living ocular tissues. with axial resolution up to 10um, it penetrates to a depth without limitation of ocular hyaline refractive medium. in this way, diagnosis of ocular diseases, especially retina diseases, is available by observing anterior and posterior segment of cornea.
pathology application: in high-density data storage, oct assists to realize multilayer optical storage and high detection sensitivity, among which, one of the most significant use is detecting early canceration in human soft tissue. oct brings back clear images according to the different spectrum features and structures between thecancer tissue and healthy tissues. thus, real time diagnosis can be made without mistake by computer signals.
non-medical application: oct has been broadening its range of application as it develops, such as measuring displacement sensor, thin photographic plate thickness and other detected object which can be transferred into displacement. besides, it is also used in measuring the residual porosity, fibrous structure and integrity of high scattering polymer molecules, coating of detected material as well as non damage detection of composite material and ceramic material.
the image above typically shows single point oct facility. non damage cross-section image of a sample can be reformed on micron grade resolution through laser beam reaching sample to as deep as 3mm.