1. Articles from Ratheesh K. Meleppat

    1-4 of 4
    1. Aperture phase modulation with adaptive optics

      Aperture phase modulation with adaptive optics

      Speckle is an inevitable consequence of the use of coherent light in imaging and acts as noise that corrupts image formation in most applications. Optical coherence tomographic imaging, as a technique employing coherence time gating, suffers from speckle. We present here a novel method of suppressing speckle noise intrinsically compatible with adaptive optics (AO) for confocal coherent imaging: modulation of the phase in the system pupil aperture with a segmented deformable mirror (DM) to introduce minor perturbations in the point spread function. This approach creates uncorrelated speckle patterns in a series of images, enabling averaging to suppress speckle noise while ...

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    2. Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

      Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

      Speckle is an inevitable consequence of the use of coherent light in optical coherence tomography (OCT), and often acts as noise that obscures micro-structures of biological tissue. We here present a novel method of suppressing speckle noise intrinsically compatible with adaptive optics (AO) in OCT system: by modulating the phase inside the imaging system pupil aperture with a segmented deformable mirror, thus producing minor perturbations in the point spread function (PSF) to create un-correlated speckle pattern between B-scans, and further averaging to wash out the speckle but maintain the structures. It is a well-controlled and universal method which can efficiently ...

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    3. Investigation of the effect of directional (off-axis) illumination on the reflectivity of retina layers in mice using swept-source optical coherence tomography

      Investigation of the effect of directional (off-axis) illumination on the reflectivity of retina layers in mice using swept-source optical coherence tomography

      Changes in visibility of the Henle fiber layer and photoreceptor bands of the human retina with illumination directionality have been reported in OCT clinical imaging. These are a direct consequence of the changes in back scattering due to fibrous tissue orientation and to waveguiding properties of the photoreceptors respectively. Here we report the preliminary results of a study on the effects of retinal images acquired with OCT of illumination directionality in the mouse retina. The quantitative assessment of the reflectivity of retinal layers of a BALB/c and WT pigmented mice was performed in-vivo using a swept-source optical coherence tomography ...

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    4. Adaptive optics with combined optical coherence tomography and scanning laser ophthalmoscopy for in vivo mouse retina imaging

      Adaptive optics with combined optical coherence tomography and scanning laser ophthalmoscopy for in vivo mouse retina imaging

      Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are two state-of-the-art imaging technologies commonly used to study retina. Adaptive Optics (AO) methodologies enable high-fidelity correction of ocular aberrations, resulting in improved resolution and sensitivity for both SLO and OCT systems. Here we present work integrating OCT into a previously described mouse retinal AO-SLO system, allowing simultaneous reflectance and fluorescence imaging. The new system allows simultaneous data acquisition of AO-SLO and AO-OCT, facilitating registration and comparison of data from both modalities. The system has data acquisition speed of 200 kHz A-scans/pixel, and high volumetric resolution.

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    1-4 of 4
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  2. Topics in the News

    1. (4 articles) Simon Fraser University
    2. (4 articles) UC Davis
    3. (4 articles) Marinko V. Sarunic
    4. (4 articles) Robert J. Zawadzki
    5. (3 articles) Pengfei Zhang
    6. (2 articles) Oregon Health & Science University
    7. (2 articles) Yifan Jian
    8. (1 articles) Myeong Jin Ju
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    Adaptive optics with combined optical coherence tomography and scanning laser ophthalmoscopy for in vivo mouse retina imaging Investigation of the effect of directional (off-axis) illumination on the reflectivity of retina layers in mice using swept-source optical coherence tomography Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography Aperture phase modulation with adaptive optics Image contrast correction method in full-field optical coherence tomography Evaluation of posterior vitreous detachment using ultrasonography and optical coherence tomography Optical coherence tomography angiography characteristics of acute retinal arterial occlusion Computed Tomography–Mediated Registration of Trapeziometacarpal Articular Cartilage Using Intraarticular Optical Coherence Tomography and Cryomicrotome Imaging: A Cadaver Study Successful Treatment of Genital Warts with Ingenol Mebutate Monitored with Optical Coherence Tomography and Reflectance Confocal Microscopy Comparison of peripapillary and subfoveal choroidal thickness in normal versus primary open-angle glaucoma (POAG) subjects using spectral domain optical coherence tomography (SD-OCT) and swept source optical coherence tomography (SS-OCT) Methods for Quantifying Optic Disc Volume and Peripapillary Deflection Volume Using Radial Optical Coherence Tomography Scans and Association with Intracranial Pressure Disease classification of macular Optical Coherence Tomography scans using deep learning software: validation on independent, multi-centre data