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
Eye movements present during acquisition of a retinal image with optical coherence tomography (OCT) introduce
motion artifacts into the image, complicating analysis and registration. This effect is especially pronounced in highresolution
data sets acquired with adaptive optics (AO)-OCT instruments. Several retinal tracking systems have been
introduced to correct retinal motion during data acquisition. We present a method for correcting motion artifacts in AOOCT
volume data after acquisition using simultaneously captured adaptive optics-scanning laser ophthalmoscope (AOSLO)
images. We extract transverse eye motion data from the AO-SLO images, assign a motion adjustment vector to
each AO-OCT A-scan, and re-sample from the scattered data back onto a regular grid. The corrected volume data
improve the accuracy of quantitative analyses of microscopic structures.
In this paper we present a Fourier-domain preconditioned conjugate gradient algorithm for the fitting step in Multi-Conjugate Adaptive Optics (MCAO) for extremely large telescopes. This algorithm is fast and robust, and it is convenient to implement with parallel processing in a real-time system. Simulation results are presented for an MCAO system for a 30-meter telescope with 2 deformable mirrors.
In this paper we present a mathematical model for a point-actuated, continuous facesheet deformable mirror. The model consists of a single partial differential equation for the facesheet coupled with a number of nonlinear algebraic constraints (one constraint per actuator). We also present a nonlinearly constrained quadratic minimization problem whose solution gives the quasi-steady state control for the mirror, given a target wavefront aberration.
In this paper, we provide an overview of the adaptive optics (AO) program for the Thirty Meter Telescope (TMT) project, including an update on requirements; the philosophical approach to developing an overall AO system architecture; the recently completed conceptual designs for facility and instrument AO systems; anticipated first light capabilities and upgrade options; and the hardware, software, and controls interfaces with the remainder of the observatory. Supporting work in AO component development, lab and field tests, and simulation and analysis is also discussed. Further detail on all of these subjects may be found in additional papers in this conference.
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