Full-field swept-source optical coherence tomography (FF-SS-OCT) provides high-resolution depth-resolved images by parallel Fourier-domain interferometric detection. Traditionally, FF-SS-OCT suffers from the cross-talk-generated noise from spatially coherent lasers. This noise reduces the image quality and limits wide adaptation of FF-SS-OCT for practical and clinical applications. To tackle this problem, we demonstrate and implement the spatiotemporal optical coherence (STOC) manipulation. In STOC, the phase of light in one of the interferometer arm is modulated in time with inhomogeneous phase masks displayed sequentially on the SLM. This modulation is synchronized with light acquisition to effectively control the spatial coherence of the detected light. A term "effectively" means that we do not generate the secondary source with imposed coherence properties (e.g. spatial incoherence). Instead the idea is to tailor the incident light to constrict the region of high fringe visibility to the spatial extents individual detection channels. Hence, SLM pixels are grouped into small blocks of uniform phase shifts. Then, phases are varied in time to modulate the light incident on the sample. By matching the dimensions of the SLM blocks to spatial extents of detection channels, we can de-correlate light from each channel. The unwanted interference between channels is washed-out and the cross-talk-generated noise is suppressed, helping to improve image quality. Here, the STOC approach is validated by imaging 1951 USAF resolution test chart covered by diffuser, scattering phantom and the rat skin ex vivo. Our results show a promising enhancement of the FF-SS-OCT capabilities that can be beneficial for imaging biological samples.
Imaging deep inside the tissue still remains a challenge for all microscopic techniques. Imaging using coherent illumination is even more challenging due to unwanted effects like speckle formation causing significant loss of imaging contrast. In our work we propose a solution to this problem by controlling the spatial distribution of phase of light illuminating the sample. In newly developed optical set-up the beam illuminating the sample first is passing through SLM that enables to fully control projected light patterns. The interferometric setup enables to perform 3D full field OCM imaging. We present the results from controlled wavefront illumination and its ability to image through scattering layers. The ultimate goal of our techniques is to create new imaging method applicable for biological 3D imaging in turbid medium.
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