Spectral calibration for spectral domain optical coherence tomography based on B-scan Doppler shift with tissue images

Abstract

We propose a simple method of linearizing spectral interference fringes of spectral domain optical coherence tomography based on B-scan Doppler frequency shift (DFS), which can be obtained by offsetting the laser beam from the pivot of a scanning mirror. We show that DFS is proportional to wavenumber. A DFS based calibration curve can be then extracted from either a single mirror image or multiple tissue images. By examining the convergence of the nonlinear coefficients of the DFS curve fitted with a polynomial equation, tissue images themselves can be used to linearize the wavenumber without requiring mirror images or additional hardware. The method is verified with both ex vivo and in vivo tissue images. Using B-scan Doppler shift, we also demonstrate significantly improved imaging quality by combining complex conjugate ambiguity removal, speckle reduction, and spectral calibration with tissue images.

In Vivo Imaging of Newt Lens Regeneration: Novel Insights Into the Regeneration Process

“…To resolve the complex conjugate ambiguity associated with spectral-domain OCT, an ∼2-mm offset was introduced relative to the pivot point of the scanner to generate Doppler frequency shifts. 30 A five-dimensional translational stage with an adapter was used to stably hold the newts during imaging, as shown in Figure 1 .…”

“…We chose 12 different time points to compare OCT images with histological images. The time points included intact eyes and eyes collected at 4,8,12,16,22,30,34,40,45,52, and 80 days postlentectomy (dpl). As indicated from previous studies, these time points represent important stages during newt lens regeneration.…”