Towards model-based adaptive optics optical coherence tomography.

Hans R G W Verstraete,Michel Verhaegen,Rolf Bilderbeek,Barry Cense,Jeroen Kalkman

doi:10.1364/oe.22.032406

Abstract

The transfer function for optical wavefront aberrations in single-mode fiber based optical coherence tomography is determined. The loss in measured OCT signal due to optical wavefront aberrations is quantified using Fresnel propagation and the calculation of overlap integrals. A distinction is made between a model for a mirror and a scattering medium model. The model predictions are validated with measurements on a mirror and a scattering medium obtained with an adaptive optics optical coherence tomography setup. Furthermore, a one-step defocus correction, based on a single A-scan measurement, is derived from the model and verified. Finally, the pseudo-convex structure of the optical coherence tomography transfer function is validated with the convergence of a hill climbing algorithm. The implications of this model for wavefront sensorless aberration correction are discussed.

Highlights

Optical coherence tomography (OCT) is a technique for non-invasive, in vivo imaging of tissue [1, 2]
The axial resolution of OCT is obtained through low coherence interferometry and is inversely proportional to the source bandwidth
It has been demonstrated that high lateral resolutions can be obtained by using adaptive optics (AO) to correct the optical wavefront aberrations on large pupils (>2 mm)

Summary

Introduction

Optical coherence tomography (OCT) is a technique for non-invasive, in vivo imaging of tissue [1, 2]. In OCT imaging of the retina the lateral resolution is hampered by the small pupil size (< 2 mm). When the pupil size is increased, large ocular aberrations are introduced. It has been demonstrated that high lateral resolutions can be obtained by using adaptive optics (AO) to correct the optical wavefront aberrations on large pupils (>2 mm). Combining the high axial resolution of OCT with the high lateral resolution of AO results in ultra-high resolution AO-OCT imaging in three dimensions. Such systems have been reported in [7,8,9,10] and demonstrated lateral and axial resolution up to 3 μm and 2- 3 μm, respectively. AO-OCT has made it possible to image the 3D architecture of individual rods and cones in vivo in the human eye [9, 11]

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