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Angular Coverage

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Timothy D. Wilkinson – One of the best experts on this subject based on the ideXlab platform.

  • Holographic wavefront sensing and correction for free space optical communications
    Asia Communications and Photonics Conference 2013, 2013
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    Using holographic techniques and a tapered laser, an optical wireless communication system with 4.6 degree Angular Coverage, 1.25GHz modulation bandwidth and the capability of sensing and correcting aberrations within system and from atmosphere is reported.

  • Free Space Communications With Beam Steering a Two-Electrode Tapered Laser Diode Using Liquid-Crystal SLM
    Journal of Lightwave Technology, 2013
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    A free space optical wireless communication system with 3 degree Angular Coverage and 1.25 GHz modulation bandwidth is reported, in which relatively narrow laser beam of a simultaneous high power, high modulation speed and ultra high modulation efficiency directly modulated two-electrode tapered laser diode is steered using a nematic phase-only Liquid-Crystal On Silicon Spatial Light Modulator (LCOS SLM) by displaying reconfigurable 256 phase level gratings.

  • Holographic beam steering a directly modulated two-electrode high brightness tapered laser diode for optical wireless communications
    Asia Communications and Photonics Conference, 2012
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    An error-free free space communication link with 3° Angular Coverage and 1.25GHz modulation bandwidth is demonstrated by beam steering an ultra high modulation efficiency bright tapered laser diode using a Liquid Crystal Spatial Light Modulator.

Feng Feng – One of the best experts on this subject based on the ideXlab platform.

  • Holographic wavefront sensing and correction for free space optical communications
    Asia Communications and Photonics Conference 2013, 2013
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    Using holographic techniques and a tapered laser, an optical wireless communication system with 4.6 degree Angular Coverage, 1.25GHz modulation bandwidth and the capability of sensing and correcting aberrations within system and from atmosphere is reported.

  • Free Space Communications With Beam Steering a Two-Electrode Tapered Laser Diode Using Liquid-Crystal SLM
    Journal of Lightwave Technology, 2013
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    A free space optical wireless communication system with 3 degree Angular Coverage and 1.25 GHz modulation bandwidth is reported, in which relatively narrow laser beam of a simultaneous high power, high modulation speed and ultra high modulation efficiency directly modulated two-electrode tapered laser diode is steered using a nematic phase-only Liquid-Crystal On Silicon Spatial Light Modulator (LCOS SLM) by displaying reconfigurable 256 phase level gratings.

  • Holographic beam steering a directly modulated two-electrode high brightness tapered laser diode for optical wireless communications
    Asia Communications and Photonics Conference, 2012
    Co-Authors: Feng Feng, Ian H. White, Timothy D. Wilkinson
    Abstract:

    An error-free free space communication link with 3° Angular Coverage and 1.25GHz modulation bandwidth is demonstrated by beam steering an ultra high modulation efficiency bright tapered laser diode using a Liquid Crystal Spatial Light Modulator.

J S Karp – One of the best experts on this subject based on the ideXlab platform.

  • Design Optimization of a Time-Of-Flight, Breast PET Scanner
    IEEE transactions on nuclear science, 2013
    Co-Authors: E. Lee, J S Karp, Matthew E. Werner, Suleman Surti
    Abstract:

    A dedicated breast positron emission tomography (PET) scanner with limited angle geometry can provide flexibility in detector placement around the patient as well as the ability to combine it with other imaging modalities. A primary challenge of a stationary limited angle scanner is the reduced image quality due to artifacts present in the reconstructed image leading to a loss in quantitative information. Previously, it has been shown that using time-of-flight (TOF) information in image reconstruction can help reduce these image artifacts arising due to missing Angular projections. Our goal in this work is to optimize the TOF, breast scanner design by performing studies for estimating image uniformity and lesion activity uptake as a function of system timing resolution, scanner Angular Coverage and shape. Our results show that (i) 1.5 × 1.5 × 15 mm3 lutetium oxy-orthosilicate (LSO) crystals provide a high spatspatial resolution and system sensitivity relative to clinical scanners, (ii) 2/3 Angular Coverage scanner design with TOF timing resolution less than 600 ps is appropriate for providing a tomographic image with fewer artifacts and good lesion uptake estimation relative to other partial ring designs studied in this work, (iii) a flat scanner design with 2/3 Angular Coverage is affected more by larger parallax error than a curved scanner geometry with the same Angular Coverage, but provides more uniform lesion contrast estimate over the imaging field-of-view (FOV), (iv) 2/3 Angular Coverage, flat, 300 ps TOF scanner design (for short, practical scan times of ≤ 5 min per breast) provides similar precision of contrast recovery coefficient (CRC) values to a full curved, non-TOF scanner, and (v) employing depth-of-interaction (DOI) measuring detector and/or implementing resolution modeling (RM) in image reconstruction lead to improved and more uniform spatial resolution and lesion contrast over the whole FOV.

  • design considerations for a limited angle dedicated breast tof pet scanner
    Physics in Medicine and Biology, 2008
    Co-Authors: Suleman Surti, J S Karp
    Abstract:

    Development of partial ring, dedicated breast positron emission tomography (PET) scanners is an active area of research. Due to the limited Angular Coverage, generation of distortion and artifact-free, fully 3D tomographic images is not possible without rotation of the detectors. With time-of-flight (TOF) information, it is possible to achieve the 3D tomographic images with limited Angular Coverage and without detector rotation. We performed simulations for a breast scanner design with a ring diameter and an axial length of 15 cm and comprising a full (180° in-plane Angular Coverage), 2/3 (120° in-plane Angular Coverage) or 1/2 (90° in-plane Angular Coverage) ring detector. Our results show that as the Angular Coverage decreases, improved timing resolution is needed to achieve distortion-free and artifact-free images with TOF. The contrast recovery coefficient (CRC) value for small hot lesions in a partial ring scanner is similar to a full ring non-TOF scanner. Our results indicate that a timing resolution of 600 ps is needed for a 2/3 ring scanner, while a timing resolution of 300 ps is needed for a 1/2 ring scanner. We also analyzed the ratio of lesion CRC to the background pixel noise (SNR) and concluded that TOF improves the SNR values of the partial ring scanner, and helps to compensate for the loss in sensitivity due to reduced geometric sensitivity in a limited angle Coverage PET scanner. In particular, it is possible to maintain similar SNR characteristic in a 2/3 ring scanner with a timing resolution of 300 ps as in a full ring non-TOF scanner.

  • design considerations for a limited angle dedicated breast tof pet scanner
    IEEE Nuclear Science Symposium, 2007
    Co-Authors: Suleman Surti, J S Karp
    Abstract:

    Development of partial ring, dedicated breast PET scanners is an active area of research. Due to the limited Angular Coverage, generation of distortion and artifact free, fully 3D tomographic images is not possible without rotation of the detectors. With TOF information it is possible to achieve the 3D tomographic images with limited Angular Coverage and without detector rotation. We performed simulations for a breast scanner design with a ring diameter and axial length of 15-cm and comprising of a Full (180 degree in-plane Angular Coverage), 2/3 (120 degree in-plane Angular Coverage), or 1/2 (90 degree in-plane Angular Coverage) ring detector. Our results show that as the Angular Coverage decreases, improved timing resolution is needed to achieve distortion and artifact-free images. The CRC value for small hot lesions is similar in these situations to a Full ring Non-TOF scanner. Our results indicate that for this geometry a timing resolution of 600 ps or better is needed for a 2/3 ring scanner, while a timing resolution of 300 ps or better is needed for a 1/2 ring scanner. The hot lesion SNR values are similar to the expected sensitivity improvement arising from TOF reconstruction and the loss in sensitivity due to reduced geometric sensitivity in a limited angle Coverage PET scanner. In particular, it is possible to maintain similar SNR characteristic in a 2/3 ring scanner with a timing resolution of 300 ps as in a full ring Non-TOF scanner.

Suleman Surti – One of the best experts on this subject based on the ideXlab platform.

  • Design Optimization of a Time-Of-Flight, Breast PET Scanner
    IEEE transactions on nuclear science, 2013
    Co-Authors: E. Lee, J S Karp, Matthew E. Werner, Suleman Surti
    Abstract:

    A dedicated breast positron emission tomography (PET) scanner with limited angle geometry can provide flexibility in detector placement around the patient as well as the ability to combine it with other imaging modalities. A primary challenge of a stationary limited angle scanner is the reduced image quality due to artifacts present in the reconstructed image leading to a loss in quantitative information. Previously, it has been shown that using time-of-flight (TOF) information in image reconstruction can help reduce these image artifacts arising due to missing Angular projections. Our goal in this work is to optimize the TOF, breast scanner design by performing studies for estimating image uniformity and lesion activity uptake as a function of system timing resolution, scanner Angular Coverage and shape. Our results show that (i) 1.5 × 1.5 × 15 mm3 lutetium oxy-orthosilicate (LSO) crystals provide a high spatial resolution and system sensitivity relative to clinical scanners, (ii) 2/3 Angular Coverage scanner design with TOF timing resolution less than 600 ps is appropriate for providing a tomographic image with fewer artifacts and good lesion uptake estimation relative to other partial ring designs studied in this work, (iii) a flat scanner design with 2/3 Angular Coverage is affected more by larger parallax error than a curved scanner geometry with the same Angular Coverage, but provides more uniform lesion contrast estimate over the imaging field-of-view (FOV), (iv) 2/3 Angular Coverage, flat, 300 ps TOF scanner design (for short, practical scan times of ≤ 5 min per breast) provides similar precision of contrast recovery coefficient (CRC) values to a full curved, non-TOF scanner, and (v) employing depth-of-interaction (DOI) measuring detector and/or implementing resolution modeling (RM) in image reconstruction lead to improved and more uniform spatial resolution and lesion contrast over the whole FOV.

  • design considerations for a limited angle dedicated breast tof pet scanner
    Physics in Medicine and Biology, 2008
    Co-Authors: Suleman Surti, J S Karp
    Abstract:

    Development of partial ring, dedicated breast positron emission tomography (PET) scanners is an active area of research. Due to the limited Angular Coverage, generation of distortion and artifact-free, fully 3D tomographic images is not possible without rotation of the detectors. With time-of-flight (TOF) information, it is possible to achieve the 3D tomographic images with limited Angular Coverage and without detector rotation. We performed simulations for a breast scanner design with a ring diameter and an axial length of 15 cm and comprising a full (180° in-plane Angular Coverage), 2/3 (120° in-plane Angular Coverage) or 1/2 (90° in-plane Angular Coverage) ring detector. Our results show that as the Angular Coverage decreases, improved timing resolution is needed to achieve distortion-free and artifact-free images with TOF. The contrast recovery coefficient (CRC) value for small hot lesions in a partial ring scanner is similar to a full ring non-TOF scanner. Our results indicate that a timing resolution of 600 ps is needed for a 2/3 ring scanner, while a timing resolution of 300 ps is needed for a 1/2 ring scanner. We also analyzed the ratio of lesion CRC to the background pixel noise (SNR) and concluded that TOF improves the SNR values of the partial ring scanner, and helps to compensate for the loss in sensitivity due to reduced geometric sensitivity in a limited angle Coverage PET scanner. In particular, it is possible to maintain similar SNR characteristic in a 2/3 ring scanner with a timing resolution of 300 ps as in a full ring non-TOF scanner.

  • design considerations for a limited angle dedicated breast tof pet scanner
    IEEE Nuclear Science Symposium, 2007
    Co-Authors: Suleman Surti, J S Karp
    Abstract:

    Development of partial ring, dedicated breast PET scanners is an active area of research. Due to the limited Angular Coverage, generation of distortion and artifact free, fully 3D tomographic images is not possible without rotation of the detectors. With TOF information it is possible to achieve the 3D tomographic images with limited Angular Coverage and without detector rotation. We performed simulations for a breast scanner design with a ring diameter and axial length of 15-cm and comprising of a Full (180 degree in-plane Angular Coverage), 2/3 (120 degree in-plane Angular Coverage), or 1/2 (90 degree in-plane Angular Coverage) ring detector. Our results show that as the Angular Coverage decreases, improved timing resolution is needed to achieve distortion and artifact-free images. The CRC value for small hot lesions is similar in these situations to a Full ring Non-TOF scanner. Our results indicate that for this geometry a timing resolution of 600 ps or better is needed for a 2/3 ring scanner, while a timing resolution of 300 ps or better is needed for a 1/2 ring scanner. The hot lesion SNR values are similar to the expected sensitivity improvement arising from TOF reconstruction and the loss in sensitivity due to reduced geometric sensitivity in a limited angle Coverage PET scanner. In particular, it is possible to maintain similar SNR characteristic in a 2/3 ring scanner with a timing resolution of 300 ps as in a full ring Non-TOF scanner.

J Xue – One of the best experts on this subject based on the ideXlab platform.

  • on 2 Angular Coverage in wireless visual sensor network deployment for 3d indoor monitoring
    ACM Southeast Regional Conference, 2017
    Co-Authors: Z Wang, Tisha Brown, T Shan, F Wang, J Xue
    Abstract:

    Extensive efforts have been devoted to achieve k-Coverage for wireless sensor networks (WSNs) deployed in the sensing area by considering omni-directional sensing ranges as seen in scalar temperature sensors, where the larger k is, fault tolerance and monitoring quality is better. However, in wireless visual sensor networks (WVSNs), the sensing range of a visual sensor is often directional and modeled as a convex triAngular shape in 2D and a pyramid-shape in 3D, which renders the k-Coverage solutions proposed for WSNs incapable of solving the problem in WVSNs. Moreover, a number of WVSN applications consider 3D indoor space monitoring, which makes previous solutions proposed for 2D WVSN Coverage less effective. In this paper, we take an initial step to tackle this challenging problem by considering 2-Coverage for WVSNs in 3D indoor space monitoring. To maximize the information that can be captured by 2 visual sensors covering a 3D location, we propose to deploy the visual sensors from different directional angles and further extend 2-Coverage to “2-AngularCoverage” to denote such unique requirements in WVSNs. We demonstrate our simulated WVSN testing platform which emulates a 3D space and highlights our objective to provide efficient 2-AngularCoverage in the indoor environment by minimizing the number of visual sensors required to cover the full regions through precision angle view monitoring. We formulate the general problem in a continuous space and then discretize our model via a lattice based approach. In addition, we also create a strategy to determine the degree of Coverage for the WVSN, where a given location needs to be covered by at least 2 visual sensors that fulfill the AngularCoverage requirement. We design an efficient greedy heuristic and an enhanced-Depth First Search algorithm to solve the discrete version problem, where the latter, if given enough time can return an optimal solution. By extensive simulations, we demonstrate that both our solutions can achieve superior performance on minimizing the number of required visual sensors for 2-AngularCoverage in 3D indoor space monitoring.

  • ACM Southeast Regional Conference – On 2-AngularCoverage in Wireless Visual Sensor Network Deployment for 3D Indoor Monitoring
    Proceedings of the SouthEast Conference, 2017
    Co-Authors: Z Wang, Tisha Brown, T Shan, F Wang, J Xue
    Abstract:

    Extensive efforts have been devoted to achieve k-Coverage for wireless sensor networks (WSNs) deployed in the sensing area by considering omni-directional sensing ranges as seen in scalar temperature sensors, where the larger k is, fault tolerance and monitoring quality is better. However, in wireless visual sensor networks (WVSNs), the sensing range of a visual sensor is often directional and modeled as a convex triAngular shape in 2D and a pyramid-shape in 3D, which renders the k-Coverage solutions proposed for WSNs incapable of solving the problem in WVSNs. Moreover, a number of WVSN applications consider 3D indoor space monitoring, which makes previous solutions proposed for 2D WVSN Coverage less effective. In this paper, we take an initial step to tackle this challenging problem by considering 2-Coverage for WVSNs in 3D indoor space monitoring. To maximize the information that can be captured by 2 visual sensors covering a 3D location, we propose to deploy the visual sensors from different directional angles and further extend 2-Coverage to “2-AngularCoverage” to denote such unique requirements in WVSNs. We demonstrate our simulated WVSN testing platform which emulates a 3D space and highlights our objective to provide efficient 2-AngularCoverage in the indoor environment by minimizing the number of visual sensors required to cover the full regions through precision angle view monitoring. We formulate the general problem in a continuous space and then discretize our model via a lattice based approach. In addition, we also create a strategy to determine the degree of Coverage for the WVSN, where a given location needs to be covered by at least 2 visual sensors that fulfill the AngularCoverage requirement. We design an efficient greedy heuristic and an enhanced-Depth First Search algorithm to solve the discrete version problem, where the latter, if given enough time can return an optimal solution. By extensive simulations, we demonstrate that both our solutions can achieve superior performance on minimizing the number of required visual sensors for 2-AngularCoverage in 3D indoor space monitoring.