The Experts below are selected from a list of 6624 Experts worldwide ranked by ideXlab platform
John S Werner - One of the best experts on this subject based on the ideXlab platform.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5×3.5×3.5 µm3. Critical to the instrument’s resolution is a customized achromatizing lens that corrects for the eye’s longitudinal chromatic aberration and an ultra Broadband Light Source (Δλ=112nm λ0=~836 nm). The eye’s transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 x 3.5 x 3.5 microm(3). Critical to the instrument's resolution is a customized achromatizing lens that corrects for the eye's longitudinal chromatic aberration and an ultra Broadband Light Source (Delta lambda=112 nm lambda(0)= approximately 836 nm). The eye's transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
Zhongping Chen - One of the best experts on this subject based on the ideXlab platform.
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digital holographic tomography based on spectral interferometry
Optics Letters, 2007Co-Authors: Zhongping ChenAbstract:A digital holographic tomography system has been developed with the use of an inexpensive Broadband Light Source and a fiber-based spectral interferometer. Multiple synthesized holograms (or object wave fields) of different wavelengths are obtained by transversely scanning a probe beam. The acquisition speed is improved compared with conventional wavelength-scanning digital holographic systems. The optical field of a volume around the object location is calculated by numerical diffraction from each synthesized hologram, and all such field volumes are numerically superposed to create the three-dimensional tomographic image. Experiments were performed to demonstrate the idea.
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in vivo optical coherence tomography of the human oral cavity and oropharynx
Archives of Otolaryngology-head & Neck Surgery, 2006Co-Authors: James M Ridgway, William B Armstrong, Shuguang Guo, Usama Mahmood, Ryan P Jackson, Terry Y Shibuya, Roger L Crumley, Zhongping Chen, Brian J F WongAbstract:Optical coherence tomography (OCT) is an evolving imaging modality that combines interferometry with low-coherence Light to produce high-resolution tissue imaging. Cross-sectional in vivo images were obtained using an OCT device consisting of a Michelson interferometer, 1.3-µm Broadband Light Source, and a handheld fiberoptic imaging probe. Image pixel resolution approached 10 µm. The mucosa of the oral cavity and oropharynx were examined in 41 patients during operative endoscopy. Optical coherence tomographic imaging was combined with endoscopic photography for gross and histologic image correlation. Optical coherence tomographic images of the oral cavity and oropharynx provided microanatomical information on the epithelium, basement membrane (BM), and supporting lamina propria (LP) of the mucosa. Normal microstructures identified in these tissues included an overlying keratin layer, papillae, ducts, glands, and blood vessels. Regions of pathologic features studied included mature scar, granulation tissue, mucous cysts, leukoplakia, and invasive cancer. Optical coherence tomographic imaging showed distinct zones of normal, altered, and ablated tissue microstructures for each pathologic process studied. Abnormal findings were directly compared with regions of normal tissue or conventional histopathologic features when tissue for analysis was available. This study provides a composite series of in vivo OCT images of the oral cavity and oropharynx in a variety of normal regions and pathologic states as well as outline future applicationsofOCTtechnology. ArchOtolaryngolHeadNeckSurg.2006;132:1074-1081
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high resolution optical coherence tomography over a large depth range with an axicon lens
Optics Letters, 2002Co-Authors: Zhihua Ding, Hongwu Ren, Yonghua Zhao, Stuart J Nelson, Zhongping ChenAbstract:In optical coherence tomography, axial and lateral resolutions are determined by the Source coherence length and the numerical aperture of the sampling lens, respectively. Whereas axial resolution can be improved by use of a Broadband Light Source, there is a trade-off between lateral resolution and focusing depth when conventional optical elements are used. We report on the incorporation of an axicon lens into the sample arm of an interferometer to overcome this limitation. Using an axicon lens with a top angle of 160 degrees , we maintained 10-microm or better lateral resolution over a focusing depth of at least 6 mm. In addition to having high lateral resolution, the focusing spot has an intensity that is approximately constant over a greater depth range than when a conventional lens is used.
Barry Cense - One of the best experts on this subject based on the ideXlab platform.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5×3.5×3.5 µm3. Critical to the instrument’s resolution is a customized achromatizing lens that corrects for the eye’s longitudinal chromatic aberration and an ultra Broadband Light Source (Δλ=112nm λ0=~836 nm). The eye’s transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 x 3.5 x 3.5 microm(3). Critical to the instrument's resolution is a customized achromatizing lens that corrects for the eye's longitudinal chromatic aberration and an ultra Broadband Light Source (Delta lambda=112 nm lambda(0)= approximately 836 nm). The eye's transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
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real time fiber based multi functional spectral domain optical coherence tomography at 1 3 mu m
Optics Express, 2005Co-Authors: Hyle B Park, Barry Cense, Seok Hyun Yun, Guillermo J Tearney, Brett E Bouma, Mark C Pierce, Mircea Mujat, Johannes F De BoerAbstract:We demonstrate a high-speed multi-functional spectral-domain optical coherence tomography system, using a Broadband Light Source centered at 1.3 µm and two InGaAs line scan cameras capable of acquiring individual axial scans in 24.4 µs, at a rate of 18,500 axial scans per second. Fundamental limitations on the accuracy of phase determination as functions of signal-to-noise ratio and lateral scan speed are presented and their relative contributions are compared. The consequences of phase accuracy are discussed for both Doppler and polarization-sensitive OCT measurements. A birefringence artifact and a calibration procedure to remove this artifact are explained. Images of a chicken breast tissue sample acquired with the system were compared to those taken with a time-domain OCT system for birefringence measurement verification. The ability of the system to image pulsatile flow in the dermis and to perform functional imaging of large volumes demonstrates the clinical potential of multi-functional spectral-domain OCT.
Michel J F Digonnet - One of the best experts on this subject based on the ideXlab platform.
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low noise and low drift in a laser driven fiber optic gyroscope with a 1 km coil
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2014Co-Authors: Jacob N Chamoun, A Evans, F A Mosca, Michel J F DigonnetAbstract:ABSTRACT We report an experimental fiber optic gyroscope (FOG) utilizing a 1085-m coil of 8-cm diameter driven with a laser of 10-MHz linewidth, with a record rotation-rate noise as low as 0.2 deg/h/ Hz and a drift below 0.038 deg/h. Simulations and comparison to the measured performance of a similar 150-m FOG show that the dominant phase-bias errors have complicated length dependencies and consist of a combination of coherent backscattering and polarization coupling errors. Keywords: Fiber optic gyroscope, inertial navigation, rotation sensing, Sagnac interferometer 1. INTRODUCTION Fiber optic gyroscopes (FOGs) based on the Sagnac effect exhibit remarkable performance characteristics, thanks in part to their inherent reciprocity, which provides superior thermal stability and immunity to several Sources of noise, and to the Broadband Light Source used to interrogate them, which pract ically eliminates other Sources of noise and drift in the fiber interferometer 1 . Commercial FOGs have very low noise and drift, for example 0.1 deg/ h and 1 deg/h, respectively, in the LN-200 unit from Northrop-Grumman
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experimental observation of low noise and low drift in a laser driven fiber optic gyroscope
Journal of Lightwave Technology, 2013Co-Authors: Seth Lloyd, Shanhui Fan, Michel J F DigonnetAbstract:We demonstrate that by driving a fiber optic gyroscope (FOG) with a laser of relatively broad linewidth ( ~ 10 MHz), both the noise and the bias drift are reduced to very low levels (0.058°/√h and 1.1°/h, respectively), comparable to the performance of the same gyroscope conventionally driven with a Broadband Light Source. When the laser linewidth is reduced to a low enough value ( ~ 2.2 kHz), the FOG exhibits a higher drift but an even lower noise, about 4 dB lower than with a Broadband Source, and only 3.5 dB above shot noise. The measured dependencies of the noise and drift on laser linewidth are in good quantitative agreement with the predictions of an advanced model of backscattering errors in a FOG interrogated with coherent Light, which confirms that the noise and drift are predominantly limited by backscattering. The use of a laser comes with the additional benefit of a much greater wavelength stability compared to a Broadband Source, which is expected to translate directly into a much more stable scale factor than possible in conventional FOGs. Residual Sources of drift and the prospects for reducing them in order to achieve inertial navigation performance are discussed.
Robert J Zawadzki - One of the best experts on this subject based on the ideXlab platform.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5×3.5×3.5 µm3. Critical to the instrument’s resolution is a customized achromatizing lens that corrects for the eye’s longitudinal chromatic aberration and an ultra Broadband Light Source (Δλ=112nm λ0=~836 nm). The eye’s transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
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ultrahigh resolution optical coherence tomography with monochromatic and chromatic aberration correction
Optics Express, 2008Co-Authors: Robert J Zawadzki, Donald T Miller, Barry Cense, Yan Zhang, Stacey S Choi, John S WernerAbstract:We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 x 3.5 x 3.5 microm(3). Critical to the instrument's resolution is a customized achromatizing lens that corrects for the eye's longitudinal chromatic aberration and an ultra Broadband Light Source (Delta lambda=112 nm lambda(0)= approximately 836 nm). The eye's transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the Light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the Broadband Light Source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.
