Phase-contrast adaptive optics scanning light ophthalmoscopy (AOSLO) has provided a new way to image transparent retinal cells without exogenous contrast. Building on this approach, we propose a novel strategy to achieve 3D quantitative phase imaging (QPI) which has potential to reveal the cellular geometry, sub-cellular contents and refractive index of translucent cells in the living retina. The approach is based on a working model that harnesses the forward propagation of an illumination beam as it passes through translucent retinal cells and is backscattered by a deeper reflective layer (DRL) such as the photoreceptor-RPE complex. The distance between the illumination focal plane and DRL provides the opportunity to measure the angular scatter/refraction of light as it passes through the cells that reside near the focal plane. Our approach positions an array detector (a digital micromiror device, DMD coupled with a photomultiplier tube) at a plane conjugate with the DRL to capture the angle-resolved, 4D information of the illuminated cells. By measuring the deviation of angular light distribution, phase of the retinal cells can be reconstructed quantitatively. The geometry of this light distribution also encodes depth information of the cells in a way similar to rendering 4D light field imaging. Here, we demonstrate the ability to perform depth ranging, perspective imaging and digital refocusing of various retinal cells and structures in the living retina including immune cells, ganglion cell somata, photoreceptor somata, and microglia using a single 4D data set that captures the angle-resolved steering of light in an AOSLO. Keywords: Adaptive optics, scanning light ophthalmoscopy, retinal imaging, quantitative phase imaging, 3D imaging
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