Coherence-gated 3D refractive index reconstruction using volumetric quantitative transmission optical coherence tomography

Abstract This paper presents volumetric quantitative transmission optical coherence tomography (vqtOCT), a hyperspectral coherence-gated holographic tomography technique for 3D refractive index (RI) reconstruction. The technique is straightforward to implement, requiring only the integration of a swept-source laser into a standard holographic tomography (HT) setup. A key feature of vqtOCT is temporal coherence gating, which enables the precise separation of photons reaching the detector at different times. Experimental validation demonstrated that by effectively isolating object photons and rejecting non-object photons, such as parasitic reflections, vqtOCT achieves the expected quantitative accuracy of the RI reconstructions, while yielding a significantly improved signal-to-noise ratio (SNR) compared to conventional HT. Furthermore, a dedicated quantitative analysis revealed that careful optimization of the temporal gate size is crucial for maximizing the overall 3D quantitative phase imaging quality.