Characterizing the resolvability of real superluminescent diode sources for application to optical coherence tomography using a low coherence interferometry model

Abstract

The axial resolution is a critical parameter in determining whether optical coherent tomography (OCT) can be used to resolve specific features in a sample image. Typically, measures of resolution have been attributed to the light source characteristics only, including the coherence length and the point spread function (PSF) width of the OCT light sources. The need to cost effectively visualize the generated PSF and OCT cross-correlated interferogram (A-scan) using many OCT light sources have led to the extrinsic evolution of the OCT simulation model presented. This research indicated that empirical resolution in vivo, as well as depending on the light source's spectral characteristics, is also strongly dependent on the optical characteristics of the tissue, including surface reflection. This research showed that this reflection could be digitally removed from the A-scan of an epithelial model, enhancing the stratum depth resolution limit (SDRL) of the subsurface tissue. Specifically, the A-scan portion above the surface, the front surface interferogram, could be digitally subtracted, rather than deconvolved, from the subsurface part of each A-scan. This front surface interferogram subtraction resulted in considerably reduced empirical SDRLs being much closer to the superluminescent diodes' resolution limits, compared to the untreated A-scan results.

Visible-light optical coherence tomography: a review

“…Since SLDs resemble laser diodes except for lack of a cavity, they are relatively inexpensive compared with the other three types of light sources 20 . The typical bandwidth of a single SLD is less than 100 nm, though the bandwidth can be broadened by different layering designs or by multiplexing 58 . The center wavelengths of SLDs are determined by the semiconductor material and range from 670 to 1600 nm 2 .…”