Spatiotemporal optical coherence (STOC) manipulation suppresses coherent cross-talk in full-field swept-source optical coherence tomography (Conference Presentation)

Abstract

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.