Speckle reduction in optical coherence tomography images of human skin by a spatial diversity method

摘要

A range of compounding techniques have been suggested for dealing with the signal degrading speckle noise in optical coherence tomography (OCT). Recent implementations of angular compounding have shown great promise, but some of the implementations require substantial modifications of the OCT system. Here, we consider a method that in principle can be fitted to most OCT systems without major modifications. Specifically, we address a spatial diversity technique for suppressing speckle noise in OCT images of human skin. The method is a variant of changing the position of the sample relative to the measuring probe. Instead of physically moving the sample, which is often not feasible for in vivo imaging, the position of the focal plane of the probe beam is shifted. If the numerical aperture is sufficiently high this spatial diversity scheme incorporates a variant of angular compounding. We have tested the scheme with a mobile fiber-based time-domain real-time OCT system. Essential enhancement was obtained in image contrast when performing in vivo imaging of normal skin and lesions. Resulting images show improved delineation of structure in correspondence with the observed improvements in contrast-to-noise ratios.