Quantitative OCT image correction using Fermat's principle and mapping arrays

Optical coherence tomography (OCT)is a relatively new developed technique to image tissue microstructure in vivo with a resolution of about 10 μn. So far, the research has focused on increasing the resolution, increasing the acquisition rate, developing new sample arm scanning techniques, or functional imaging like color Doppler OCT. But one of the main advantages of OCT compared to ultrasound, non-contact imaging, also results in a mayor image distortion: refraction at the air-tissue interface. Also, applied scanning configurations can lead to deformed images. Both errors prevent actuate distance and angle measurements on OCT images, necessary e.g. for Glaucoma diagnosis in the anterior segment of the eye. We describe a methodology for quantitative image correction in OCT which includes procedures for correction of arbitrary spatial warping caused by non-uniform axial reference and lateral sample scan patterns, as well as a novel approach for refraction correction in layered media based on Fermat's principle. The de-warping corrections are implemented in real-time by use of pointer (mapping) arrays, while the refraction correction algorithm is more computationally intensive and is performed off-line.