The Experts below are selected from a list of 40791 Experts worldwide ranked by ideXlab platform
Daniel X Hammer - One of the best experts on this subject based on the ideXlab platform.
-
multimodal Adaptive Optics retinal imager design and performance
Journal of The Optical Society of America A-optics Image Science and Vision, 2012Co-Authors: Daniel X Hammer, Daniel R Ferguson, Nicusor Iftimia, Mircea Mujat, Ankit H Patel, Emily Plumb, Toco Yuen Ping Chui, James D Akula, Anne B FultonAbstract:Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are complementary imaging modalities, the combination of which can provide clinicians with a wealth of information to detect retinal diseases, monitor disease progression, or assess new therapies. Adaptive Optics (AO) is a tool that enables correction of wavefront distortions from ocular aberrations. We have developed a multimodal Adaptive Optics system (MAOS) for high-resolution multifunctional use in a variety of research and clinical applications. The system integrates both OCT and SLO imaging channels into an AO beam path. The Optics and hardware were designed with specific features for simultaneous SLO/OCT output, for high-fidelity AO correction, for use in humans, primates, and small animals, and for efficient location and orientation of retinal regions of interest. The MAOS system was tested on human subjects and rodents. The design, performance characterization, and initial representative results from the human and animal studies are presented and discussed.
-
compact Adaptive Optics line scanning ophthalmoscope
Optics Express, 2009Co-Authors: Mircea Mujat, Nicusor Iftimia, Daniel R Ferguson, Daniel X HammerAbstract:We have developed a compact retinal imager that integrates Adaptive Optics (AO) into a line scanning ophthalmoscope (LSO). The bench-top AO-LSO instrument significantly reduces the size, complexity, and cost of research AO scanning laser ophthalmoscopes (AOSLOs), for the purpose of moving Adaptive Optics imaging more rapidly into routine clinical use. The AO-LSO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration and cone counting.
-
compact Adaptive Optics line scanning laser ophthalmoscope
Progress in biomedical optics and imaging, 2009Co-Authors: Daniel X Hammer, Nicusor Iftimia, Mircea Mujat, Daniel R FergusonAbstract:We have developed a compact retinal imager that integrates Adaptive Optics (AO) into a line scanning laser ophthalmoscope (LSLO). The bench-top AO-LSLO instrument significantly reduces the size, complexity, and cost of research AOSLOs, for the purpose of moving Adaptive Optics imaging more rapidly into routine clinical use. The AO-LSLO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSLO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration, cone counting, and montage stitching.
-
large field of view modular stabilized Adaptive Optics based scanning laser ophthalmoscope
Journal of The Optical Society of America A-optics Image Science and Vision, 2007Co-Authors: Stephen A Burns, Remy Tumbar, Ann E Elsner, Daniel Ferguson, Daniel X HammerAbstract:We describe the design and performance of an Adaptive Optics retinal imager that is optimized for use during dynamic correction for eye movements. The system incorporates a retinal tracker and stabilizer, a wide field line scan Scanning Laser Ophthalmocsope (SLO), and a high resolution MEMS based Adaptive Optics SLO. The detection system incorporates selection and positioning of confocal apertures, allowing measurement of images arising from different portions of the double pass retinal point spread function (psf). System performance was excellent. The Adaptive Optics increased the brightness and contrast for small confocal apertures by more than 2x, and decreased the brightness of images obtained with displaced apertures, confirming the ability of the Adaptive Optics system to improve the pointspread function. The retinal image was stabilized to within 18 microns 90% of the time. Stabilization was sufficient for cross-correlation techniques to automatically align the images.
-
precision targeting with a tracking Adaptive Optics scanning laser ophthalmoscope
Biomedical optics, 2006Co-Authors: Daniel X Hammer, Daniel R Ferguson, Nicusor Iftimia, Chad E Bigelow, Teoman E Ustun, Gary D Noojin, David J Stolarski, Harvey M Hodnett, Michelle L Imholte, Semih S KumruAbstract:We have designed and built a novel imaging system combining scanning laser ophthalmoscopy, active image stabilization, and Adaptive Optics for precise imaging and targeting of retinal structures. System capabilities are demonstrated in humans and animals.
Li Xuan - One of the best experts on this subject based on the ideXlab platform.
-
astronomical observation by 2 meter telescope based on liquid crystal Adaptive Optics with phase diversity
Optics Communications, 2019Co-Authors: Chengliang Yang, Zhaoliang Cao, Xingyun Zhang, Peiguang Zhang, Li XuanAbstract:Abstract A set of liquid crystal Adaptive Optics system for visible light is installed for 2-meter telescope in Changchun, China. To get higher resolution images after Adaptive Optics, phase diversity (PD) is applied. Two liquid crystal spatial light modulators were used for two polarized states of light, and they were also used for two channel correction of focused image and diversity image. Observations about star HD 29139 were performed on March 23, 2018. The results of the star with the PD show that the full width half maximum was decreased from about 10 pixels to 4 pixels, corresponding to angular resolution improved from 0.5” to 0.2”. The peak intensity was improved by 66.7% after the PD. The root mean square of the wavefront estimated using the PD agrees with the Strehl ratio of observed image after Adaptive Optics. The observed results indicate that the PD technique can significantly improve the image resolution after liquid crystal Adaptive Optics.
-
high precision system modeling of liquid crystal Adaptive Optics systems
Optics Express, 2017Co-Authors: Xingyun Zhang, Zhaoliang Cao, Yukun Wang, Shaoxin Wang, Chengliang Yang, Li XuanAbstract:In this paper, we present a heuristic method to simplify the liquid crystal Adaptive Optics system (LCAOS) into a single-input-single-output (SISO) system, then build the dynamic model of LCAOS based on subspace identification. Results show that the identified model could accurately describe the dynamical behavior of LCAOS (97% match), with extremely low complexity. The wonderful features of low complexity and high precision, make the identified model highly beneficial for model based controller design, system analysis and dynamical behavior simulation of liquid crystal Adaptive Optics systems.
-
improve the accuracy of interaction matrix measurement for liquid crystal Adaptive Optics systems
Optics Express, 2014Co-Authors: Xingyun Zhang, Zhaoliang Cao, Li XuanAbstract:We present a novel method to measure the interaction matrix of liquid-crystal Adaptive Optics systems, by applying least squares method to mitigate the impact of measurement noise. Experimental results showed a dramatic gain in the accuracy of interaction matrix, and a considerable improvement in image resolution with open loop Adaptive Optics correction.
-
image restoration of the open loop Adaptive Optics retinal imaging system based on optical transfer function analysis
Optics Communications, 2013Co-Authors: Mingliang Xia, Li XuanAbstract:Abstract The residual aberrations of the Adaptive Optics retinal imaging system will decrease the quality of the retinal images. To overcome this obstacle, we found that the optical transfer function (OTF) of the Adaptive Optics retinal imaging system can be described as the Levy stable distribution. Then a new method is introduced to estimate the OTF of the open-loop Adaptive Optics system, based on analyzing the residual aberrations of the open-loop Adaptive Optics system in the residual aberrations measuring mode. At last, the estimated OTF is applied to restore the retinal images of the open-loop Adaptive Optics retinal imaging system. The contrast and resolution of the restored image is significantly improved with the Laplacian sum (LS) from 0.0785 to 0.1480 and gray mean grads (GMG) from 0.0165 to 0.0306.
William S Tuten - One of the best experts on this subject based on the ideXlab platform.
-
Adaptive Optics scanning laser ophthalmoscope based microperimetry
Investigative Ophthalmology & Visual Science, 2011Co-Authors: William S Tuten, Pavan TiruveedhulaAbstract:ABSTRACTPurpose.To develop and test the application of an Adaptive Optics scanning laser ophthalmoscope (AOSLO) with eye tracking for high-resolution microperimetric testing.Methods.An AOSLO was used to conduct simultaneous high-resolution retinal imaging and visual function testing in six normal su
Daniel R Ferguson - One of the best experts on this subject based on the ideXlab platform.
-
multimodal Adaptive Optics retinal imager design and performance
Journal of The Optical Society of America A-optics Image Science and Vision, 2012Co-Authors: Daniel X Hammer, Daniel R Ferguson, Nicusor Iftimia, Mircea Mujat, Ankit H Patel, Emily Plumb, Toco Yuen Ping Chui, James D Akula, Anne B FultonAbstract:Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are complementary imaging modalities, the combination of which can provide clinicians with a wealth of information to detect retinal diseases, monitor disease progression, or assess new therapies. Adaptive Optics (AO) is a tool that enables correction of wavefront distortions from ocular aberrations. We have developed a multimodal Adaptive Optics system (MAOS) for high-resolution multifunctional use in a variety of research and clinical applications. The system integrates both OCT and SLO imaging channels into an AO beam path. The Optics and hardware were designed with specific features for simultaneous SLO/OCT output, for high-fidelity AO correction, for use in humans, primates, and small animals, and for efficient location and orientation of retinal regions of interest. The MAOS system was tested on human subjects and rodents. The design, performance characterization, and initial representative results from the human and animal studies are presented and discussed.
-
compact Adaptive Optics line scanning ophthalmoscope
Optics Express, 2009Co-Authors: Mircea Mujat, Nicusor Iftimia, Daniel R Ferguson, Daniel X HammerAbstract:We have developed a compact retinal imager that integrates Adaptive Optics (AO) into a line scanning ophthalmoscope (LSO). The bench-top AO-LSO instrument significantly reduces the size, complexity, and cost of research AO scanning laser ophthalmoscopes (AOSLOs), for the purpose of moving Adaptive Optics imaging more rapidly into routine clinical use. The AO-LSO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration and cone counting.
-
compact Adaptive Optics line scanning laser ophthalmoscope
Progress in biomedical optics and imaging, 2009Co-Authors: Daniel X Hammer, Nicusor Iftimia, Mircea Mujat, Daniel R FergusonAbstract:We have developed a compact retinal imager that integrates Adaptive Optics (AO) into a line scanning laser ophthalmoscope (LSLO). The bench-top AO-LSLO instrument significantly reduces the size, complexity, and cost of research AOSLOs, for the purpose of moving Adaptive Optics imaging more rapidly into routine clinical use. The AO-LSLO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSLO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration, cone counting, and montage stitching.
-
precision targeting with a tracking Adaptive Optics scanning laser ophthalmoscope
Biomedical optics, 2006Co-Authors: Daniel X Hammer, Daniel R Ferguson, Nicusor Iftimia, Chad E Bigelow, Teoman E Ustun, Gary D Noojin, David J Stolarski, Harvey M Hodnett, Michelle L Imholte, Semih S KumruAbstract:We have designed and built a novel imaging system combining scanning laser ophthalmoscopy, active image stabilization, and Adaptive Optics for precise imaging and targeting of retinal structures. System capabilities are demonstrated in humans and animals.
Xingyun Zhang - One of the best experts on this subject based on the ideXlab platform.
-
astronomical observation by 2 meter telescope based on liquid crystal Adaptive Optics with phase diversity
Optics Communications, 2019Co-Authors: Chengliang Yang, Zhaoliang Cao, Xingyun Zhang, Peiguang Zhang, Li XuanAbstract:Abstract A set of liquid crystal Adaptive Optics system for visible light is installed for 2-meter telescope in Changchun, China. To get higher resolution images after Adaptive Optics, phase diversity (PD) is applied. Two liquid crystal spatial light modulators were used for two polarized states of light, and they were also used for two channel correction of focused image and diversity image. Observations about star HD 29139 were performed on March 23, 2018. The results of the star with the PD show that the full width half maximum was decreased from about 10 pixels to 4 pixels, corresponding to angular resolution improved from 0.5” to 0.2”. The peak intensity was improved by 66.7% after the PD. The root mean square of the wavefront estimated using the PD agrees with the Strehl ratio of observed image after Adaptive Optics. The observed results indicate that the PD technique can significantly improve the image resolution after liquid crystal Adaptive Optics.
-
high precision system modeling of liquid crystal Adaptive Optics systems
Optics Express, 2017Co-Authors: Xingyun Zhang, Zhaoliang Cao, Yukun Wang, Shaoxin Wang, Chengliang Yang, Li XuanAbstract:In this paper, we present a heuristic method to simplify the liquid crystal Adaptive Optics system (LCAOS) into a single-input-single-output (SISO) system, then build the dynamic model of LCAOS based on subspace identification. Results show that the identified model could accurately describe the dynamical behavior of LCAOS (97% match), with extremely low complexity. The wonderful features of low complexity and high precision, make the identified model highly beneficial for model based controller design, system analysis and dynamical behavior simulation of liquid crystal Adaptive Optics systems.
-
improve the accuracy of interaction matrix measurement for liquid crystal Adaptive Optics systems
Optics Express, 2014Co-Authors: Xingyun Zhang, Zhaoliang Cao, Li XuanAbstract:We present a novel method to measure the interaction matrix of liquid-crystal Adaptive Optics systems, by applying least squares method to mitigate the impact of measurement noise. Experimental results showed a dramatic gain in the accuracy of interaction matrix, and a considerable improvement in image resolution with open loop Adaptive Optics correction.