Dr. Yan Zhang Profile

Dr. Yan Zhang

at Indiana Univ

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Author

Publications (9)

Proceedings Article | 11 March 2008 Paper

Ultra-high resolution adaptive optics: optical coherence tomography for in vivo imaging of healthy and diseased retinal structures

Robert Zawadzki, Yan Zhang, Steven Jones, Stacey Choi, Barry Cense, Julia Evans, Donald Miller, Scot Olivier, John Werner

Proceedings Volume 6844, 684408 (2008) https://doi.org/10.1117/12.764115

KEYWORDS: Adaptive optics optical coherence tomography, Optical coherence tomography, Adaptive optics, Speckle, Image resolution, Visualization, Eye, Retina, Imaging systems, In vivo imaging

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Proceedings Article | 5 March 2007 Paper

Application of adaptive optics: optical coherence tomography for in vivo imaging of microscopic structures in the retina and optic nerve head

Robert Zawadzki, Yan Zhang, Steven Jones, Stacey Choi, Barry Cense, Diana Chen, Alfred Fuller, Donald Miller, Scot Olivier, John Werner

Proceedings Volume 6426, 64261O (2007) https://doi.org/10.1117/12.701512

KEYWORDS: Adaptive optics optical coherence tomography, Optical coherence tomography, Adaptive optics, Visualization, Retina, Eye, Deformable mirrors, In vivo imaging, Head, Wavefronts

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Proceedings Article | 5 March 2007 Paper

Volumetric imaging of inner retina with adaptive optics spectral-domain optical coherence tomography

Yan Zhang, Barry Cense, Ravi Jonnal, Weihua Gao, Steve Jones, Scot Olivier, Donald Miller

Proceedings Volume 6426, 64261P (2007) https://doi.org/10.1117/12.701960

KEYWORDS: Adaptive optics, Retina, Eye, Capillaries, Mirrors, Retinal scanning, Cameras, Cones, Nerve, Optical coherence tomography

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Adaptive optics (AO) coupled with ultra-fast spectral-domain optical coherence tomography (SD-OCT) has achieved the necessary 3D resolution, sensitivity, and speed for imaging the microscopic retina at the cellular level. While this technology has been rigorously applied to evaluating the 3D morphology of cone photoreceptors, similar detailed studies of cell-sized structures in the inner retina have yet to be undertaken. In this paper, we improve the technical performance of our AO ultrafast SD-OCT and investigate its use for imaging the microscopic inner retina, in particular the nerve fiber layer (NFL) and retinal capillary network. To maximize lateral resolution within the inner retina, focus was controlled with a high stroke, 37-actuator bimorph mirror (AOptix) that also served as the wavefront corrector of the AO. The AO system operated at a closed-loop rate of 25 Hz. The SD-OCT sub-system consisted of a superluminescent diode (&lgr;= 842 nm, &Dgr;&lgr;= 50 nm) and a 512 pixel line scan charge-coupled device (CCD) that acquired 72,000 A-scans/sec. Three different B-scan lengths (36, 60, and 120 A-scans/B-scan), which correspond to B-scan exposure durations of 0.5, 0.83, and 1.67 ms, were evaluated to determine the maximum B-scan length that could be tolerated without noticeable loss in image quality due to eye motion in the well fixated eye. Additional technical improvements included sub-pixel registration to remove instrument error and axial registration of the volume images. Small volume images were acquired at 2 and 7 degrees retinal eccentricity with focus systematically shifted through the retina. Small capillaries, some approaching the smallest in the human eye, were readily detected with AO SD-OCT. Appearance of the nerve fiber layer varied noticeably with depth. The most inner portion (presumably the inner limiting membrane) appeared as a thin irregular surface with little characteristic speckle noise. Within the NFL, complex striation patterns (presumably NFL bundles) were observed throughout the entire thickness with pattern density highest in the inner portion (~15 &mgr;m) and large corrugations (~35 &mgr;m) at the interface with the ganglion cell layer below. Speckle noise was significant throughout the NFL.

Proceedings Article | 5 March 2007 Paper

High-speed adaptive optics functional imaging of cone photoreceptors at a 100 MHz pixel rate

Ravi Jonnal, Jungtae Rha, Yan Zhang, Barry Cense, Donald Miller

Proceedings Volume 6426, 64261N (2007) https://doi.org/10.1117/12.702028

KEYWORDS: Cones, Scintillation, Adaptive optics, Retina, Cameras, Eye, Charge-coupled devices, Functional imaging, Adaptive optics retinal cameras, Signal to noise ratio

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Proceedings Article | 9 February 2007 Paper

Ultrahigh-resolution adaptive optics - optical coherence tomography: toward isotropic 3-um resolution for in vivo retinal imaging

Robert Zawadzki, Yan Zhang, Steven Jones, R. Daniel Ferguson, Stacey Choi, Barry Cense, Julia Evans, Diana Chen, Donald Miller, Scot Olivier, John Werner

Proceedings Volume 6429, 642909 (2007) https://doi.org/10.1117/12.704639

KEYWORDS: Adaptive optics, Adaptive optics optical coherence tomography, Optical coherence tomography, Eye, Light sources, Wavefronts, Image resolution, Chromatic aberrations, Retina, Imaging systems

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Proceedings Article | 22 June 2006 Paper

Prospects and limitations for large numbers of multi-layers in optical data storage

Sang-Ki Park, Tom Milster, Yan Zhang

Proceedings Volume 6282, 628210 (2006) https://doi.org/10.1117/12.685227

KEYWORDS: Dielectrics, Metals, Refractive index, Reflectivity, Silver, Coating, Gold, Transmittance, Thin films, Tolerancing

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Proceedings Article | 8 June 2006 Paper

Imaging the living retina at the cellular level with AO parallel spectral-domain optical coherence tomography

Donald Miller, Yan Zhang, Jungtae Rha, Ravi Jonnal, Weihua Gao

Proceedings Volume 6018, 601803 (2006) https://doi.org/10.1117/12.669239

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Proceedings Article | 7 March 2006 Paper

Motion-free volumetric retinal imaging with adaptive optics spectral-domain optical coherence tomography

Yan Zhang, Jungtae Rha, Abraham Cense, Ravi Jonnal, Weihua Gao, Robert Zawadzki, John Werner, Steve Jones, Scot Olivier, Donald Miller

Proceedings Volume 6138, 613802 (2006) https://doi.org/10.1117/12.649006

KEYWORDS: Adaptive optics, Eye, Retina, Mirrors, Cameras, Optical coherence tomography, Cones, Retinal scanning, Adaptive optics optical coherence tomography, Distortion

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Proceedings Article | 13 April 2005 Paper

Single-shot retinal imaging with AO spectral OCT

Yan Zhang, Jungtae Rha, Ravi Jonnal, Donald Miller

Proceedings Volume 5690, (2005) https://doi.org/10.1117/12.592831

KEYWORDS: Adaptive optics, Optical coherence tomography, Retina, Cameras, Cones, Eye, Retinal scanning, Image segmentation, Mirrors, Floods

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Showing 5 of 9 publications

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