Crosstalk-free volumetric in vivo imaging of a human retina with Fourier-domain full-field optical coherence tomography

Abstract

Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is currently the fastest volumetric imaging technique that is able to generate a single 3-D volume of retina in less than 9 ms, corresponding to a voxel rate of 7.8 GHz. FD-FF-OCT is based on a fast camera, a rapidly tunable laser source, and Fourier-domain signal detection. However, crosstalk appearing due to multiply scattered light corrupts images with the speckle pattern, and therefore, lowers image quality. Here, for the first time, we report on a system that can acquire essentially crosstalk-free volumes of the retina by using a fast deformable membrane. It enables the visualization of choroids and a clear delineation of the retinal layers that is not possible with conventional FD-FF-OCT.

Kilohertz retinal FF-SS-OCT and flood imaging with hardware-based adaptive optics

“…DAC has also been employed in line-scanning TD-OCT, which mitigates the contributions of axial motion to the phase of the interference fringe [13]. In FF-SS-OCT, spatial coherence manifests as cross-talk, and approaches have been demonstrated to mitigate this source of noise [4,7].…”

In vivo imaging of the human cornea with high-speed and high-resolution Fourier-domain full-field optical coherence tomography

“…The processing pipeline proceeds similarly to the one used for retinal imaging [41]. However, we are now using generalized spatial filtering, automatic dispersion compensation, digital aberration correction, and automatic corneal curvature correction.…”

“…To this end, we divided input images by a low-pass background, which was obtained by applying a Gaussian blur on input images. Next, we normalized images using a method developed for endothelial images [41]. Finally, we smoothed images using a Gaussian blur.…”

“…7(e) by the red curve. The intensity envelope shows how quickly light that is backscattered from a sample decorrelates axially with the defocus, which we call SCG function [41,45]. The FWHM of the curve was estimated to be 400 µm from Fig.…”

“…Such incoherent illumination effectively broadens the laser spot on the retina to the acceptable MPE intensity levels. We have previously used DM to remove crosstalk in FD-FF-OCT images of skin [39] and retina [41]. In corneal imaging, however, crosstalk is less of an issue due to the low corneal scattering, and therefore, the DM is primarily used to circumvent the laser safety problem.…”