Diffuse-illumination holographic optical coherence tomography

TL;DR

This paper introduces a diffuse-illumination holographic OCT technique that significantly reduces multiply scattered light speckle, enhances image quality, and maintains holographic reconstruction over typical OCT axial ranges.

Contribution

The study demonstrates a novel diffuse illumination method in holographic OCT that reduces multiple scattering effects and preserves holographic capabilities with partially incoherent light sources.

Findings

Speckle from multiply scattered light can be arbitrarily reduced.

Image quality improvements are substantial due to speckle reduction.

Holographic reconstruction is maintained over typical OCT axial ranges.

Abstract

Holographic optical coherence tomography (OCT) is a powerful imaging technique, but its ability to reveal low-reflectivity features is limited. In this study, we performed holographic OCT by incoherently averaging volumes with changing diffuse illumination of numerical aperture (NA) equal to the detection NA. While the reduction of speckle from singly scattered light is only modest, we discovered that speckle from multiply scattered light can be arbitrarily reduced, resulting in substantial improvements in image quality. This technique also offers the advantage of suppressing noises arising from spatial coherence, and can be implemented with a partially spatially incoherent light source for further mitigation of multiple scattering. Finally, we show that although holographic reconstruction capabilities are increasingly lost with decreasing spatial coherence, they can be retained over an axial range sufficient to standard OCT applications.