Digital aberration correction enhances field of view in visible-light optical coherence microscopy

Abstract

In optical coherence microscopy, optical aberrations commonly result in astigmatism-dominated wavefront errors in the peripheral regions of the optical objective, primarily elongating the microscope’s point-spread function along the radial direction in the vicinity of the focal plane. We report on enhanced-field-of-view optical coherence microscopy through computational aberration correction in the visible-light range. An isotropic spatial resolution of 2.5 µm was achieved over an enhanced lateral field of view spanning 1.3 mm × 1.6 mm, as experimentally verified in a micro-bead phantom and further demonstrated in ex vivo tissue samples. The extended field of view achieved by the digital aberration correction facilitates the use of low-cost systems by averting the need for high-quality objectives.

Computational 3D resolution enhancement for optical coherence tomography with a narrowband visible light source

“…The complex-valued OCT en face images were Fourier transformed in the lateral direction to obtain the field in the pupil plane. The field in the pupil plane was shifted such that the lateral center of mass was in the center [34], after which it was transformed back to the spatial domain. These en face images were divided into four square areas, each of which was independently corrected to also address shift-variant aberrations.…”

“…The obtained slope differences were fitted with the 𝑥 and 𝑦 gradient of 12 Zernike polynomials (from second to fourth order) [33]. By using two randomly chosen sub-apertures instead of the center aperture as reference, the sensitivity to speckle was reduced [34,35]. Magnitude OCT images were used rather than intensity OCT images to increase the sensitivity to the entire object structure rather than a few high-intensity peaks.…”