The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Armando Viviano Razionale - One of the best experts on this subject based on the ideXlab platform.

  • structured light stereo catadioptric scanner based on a Spherical Mirror
    Optics and Lasers in Engineering, 2018
    Co-Authors: Sandro Barone, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    Abstract The present paper describes the development and characterization of a structured light stereo catadioptric scanner for the omnidirectional reconstruction of internal surfaces. The proposed approach integrates two digital cameras, a multimedia projector and a Spherical Mirror, which is used to project the structured light patterns generated by the light emitter and, at the same time, to reflect into the cameras the modulated fringe patterns diffused from the target surface. The adopted optical setup defines a non-central catadioptric system, thus relaxing any geometrical constraint in the relative placement between optical devices. An analytical solution for the reflection on a Spherical surface is proposed with the aim at modelling forward and backward projection tasks for a non-central catadioptric setup. The feasibility of the proposed active catadioptric scanner has been verified by reconstructing various target surfaces. Results demonstrated a great influence of the target surface distance from the Mirror's centre on the measurement accuracy. The adopted optical configuration allows the definition of a metrological 3D scanner for surfaces disposed within 120 mm from the Mirror centre.

  • An Omnidirectional Vision Sensor Based on a Spherical Mirror Catadioptric System
    MDPI AG, 2018
    Co-Authors: Sandro Barone, Marina Carulli, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    The combination of Mirrors and lenses, which defines a catadioptric sensor, is widely used in the computer vision field. The definition of a catadioptric sensors is based on three main features: hardware setup, projection modelling and calibration process. In this paper, a complete description of these aspects is given for an omnidirectional sensor based on a Spherical Mirror. The projection model of a catadioptric system can be described by the forward projection task (FP, from 3D scene point to 2D pixel coordinates) and backward projection task (BP, from 2D coordinates to 3D direction of the incident light). The forward projection of non-central catadioptric vision systems, typically obtained by using curved Mirrors, is usually modelled by using a central approximation and/or by adopting iterative approaches. In this paper, an analytical closed-form solution to compute both forward and backward projection for a non-central catadioptric system with a Spherical Mirror is presented. In particular, the forward projection is reduced to a 4th order polynomial by determining the reflection point on the Mirror surface through the intersection between a sphere and an ellipse. A matrix format of the implemented models, suitable for fast point clouds handling, is also described. A robust calibration procedure is also proposed and applied to calibrate a catadioptric sensor by determining the Mirror radius and center with respect to the camera

  • catadioptric stereo vision system using a Spherical Mirror
    Procedia structural integrity, 2018
    Co-Authors: Sandro Barone, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    Abstract In the computer vision field, the reconstruction of target surfaces is usually achieved by using 3D optical scanners assembled integrating digital cameras and light emitters. However, these solutions are limited by the low field of view, which requires multiple acquisition from different views to reconstruct complex free-form geometries. The combination of Mirrors and lenses (catadioptric systems) can be adopted to overcome this issue. In this work, a stereo catadioptric optical scanner has been developed by assembling two digital cameras, a Spherical Mirror and a multimedia white light projector. The adopted configuration defines a non-single viewpoint system, thus a non-central catadioptric camera model has been developed. An analytical solution to compute the projection of a scene point onto the image plane (forward projection) and vice-versa (backward projection) is presented. The proposed optical setup allows omnidirectional stereo vision thus allowing the reconstruction of target surfaces with a single acquisition. Preliminary results, obtained measuring a hollow specimen, demonstrated the effectiveness of the described approach.

Gang Shu - One of the best experts on this subject based on the ideXlab platform.

  • efficient fluorescence collection from trapped ions with an integrated Spherical Mirror
    Physical Review A, 2010
    Co-Authors: Gang Shu, Nathan Kurz, M R Dietrich, B B Blinov
    Abstract:

    Efficient collection of fluorescence from trapped ions is crucial for quantum optics and quantum computing applications, specifically for qubit state detection and in generating single photons for ion-photon and remote ion entanglement. In a typical setup, only a few percent of the ion fluorescence is intercepted by the aperture of the imaging optics. We employ a simple metallic Spherical Mirror integrated with a linear Paul ion trap to achieve a photon collection efficiency of at least $10%$ from a single Ba${}^{+}$ ion. An aspheric corrector is used to reduce the aberrations caused by the Mirror and achieve high image quality.

  • Trapped ion imaging with a high numerical aperture Spherical Mirror
    Journal of Physics B: Atomic Molecular and Optical Physics, 2009
    Co-Authors: Gang Shu, Matthew Dietrich, Nathan Kurz, Boris Blinov
    Abstract:

    Efficient collection and analysis of trapped ion qubit fluorescence is essential for robust qubit state detection in trapped ion quantum computing schemes. We discuss simple techniques of improving photon collection efficiency using high numerical aperture (N.A.) reflective optics. To test these techniques we placed a Spherical Mirror with an effective N.A. of about 0.9 inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate stable and reliable trapping of single barium ions, in excellent agreement with our simulations of the electric field in this setup. While a large N.A. Spherical Mirror introduces significant Spherical aberration, the ion image quality can be greatly improved by a specially designed aspheric corrector lens located outside the vacuum system. Our simulations show that the Spherical Mirror/corrector design is an easy and cost-effective way to achieve high photon collection rates when compared to a more sophisticated parabolic Mirror setup.

  • Improving Ion Fluorescence Collection by Integrating High Numerical Aperture Spherical Mirror into Ion Trap
    Frontiers in Optics 2009 Laser Science XXV Fall 2009 OSA Optics & Photonics Technical Digest, 2009
    Co-Authors: Gang Shu, Matthew Dietrich, Nathan Kurz, Boris Blinov
    Abstract:

    We integrated a high N.A. Spherical Mirror into a Paul trap and improved its image by special aspheric correctors. We designed a trap based on metallic Spherical Mirror which greatly increases the ion-photon/ion-ion entanglement efficiency.

Souichi Telada - One of the best experts on this subject based on the ideXlab platform.

  • three Spherical Mirror test for radius of curvature measurement using a fabry perot cavity
    Optics Express, 2019
    Co-Authors: Youichi Bitou, Osamu Sato, Souichi Telada
    Abstract:

    A three-Spherical-Mirror test method that uses a Fabry-Perot (FP) cavity is proposed for a radius of curvature measurement system, especially for radii larger than 10 m. By using the three-Spherical-Mirror test with mode spacing measurement in an FP cavity, the local value of the radius of curvature of a Mirror can be determined in situ and this Mirror can then be used as the reference Spherical Mirror in a radius of curvature measurement system. We demonstrated determinations of radii of curvature of around 10 m using the three-Spherical-Mirror test with uncertainties of around 1.5 × 10−4 and then measured the radius of curvature of around 20 m with uncertainties of around 3.1 × 10−4 by using the Spherical Mirror, of which the radius of curvature was determined by the three-Spherical-Mirror test, as the reference sphere. The proposed system has high practical applicability because measurements can be conducted under usual air conditions and the measurement results are directly traceable to the time standard because beat frequency measurement is used.

Sandro Barone - One of the best experts on this subject based on the ideXlab platform.

  • structured light stereo catadioptric scanner based on a Spherical Mirror
    Optics and Lasers in Engineering, 2018
    Co-Authors: Sandro Barone, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    Abstract The present paper describes the development and characterization of a structured light stereo catadioptric scanner for the omnidirectional reconstruction of internal surfaces. The proposed approach integrates two digital cameras, a multimedia projector and a Spherical Mirror, which is used to project the structured light patterns generated by the light emitter and, at the same time, to reflect into the cameras the modulated fringe patterns diffused from the target surface. The adopted optical setup defines a non-central catadioptric system, thus relaxing any geometrical constraint in the relative placement between optical devices. An analytical solution for the reflection on a Spherical surface is proposed with the aim at modelling forward and backward projection tasks for a non-central catadioptric setup. The feasibility of the proposed active catadioptric scanner has been verified by reconstructing various target surfaces. Results demonstrated a great influence of the target surface distance from the Mirror's centre on the measurement accuracy. The adopted optical configuration allows the definition of a metrological 3D scanner for surfaces disposed within 120 mm from the Mirror centre.

  • An Omnidirectional Vision Sensor Based on a Spherical Mirror Catadioptric System
    MDPI AG, 2018
    Co-Authors: Sandro Barone, Marina Carulli, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    The combination of Mirrors and lenses, which defines a catadioptric sensor, is widely used in the computer vision field. The definition of a catadioptric sensors is based on three main features: hardware setup, projection modelling and calibration process. In this paper, a complete description of these aspects is given for an omnidirectional sensor based on a Spherical Mirror. The projection model of a catadioptric system can be described by the forward projection task (FP, from 3D scene point to 2D pixel coordinates) and backward projection task (BP, from 2D coordinates to 3D direction of the incident light). The forward projection of non-central catadioptric vision systems, typically obtained by using curved Mirrors, is usually modelled by using a central approximation and/or by adopting iterative approaches. In this paper, an analytical closed-form solution to compute both forward and backward projection for a non-central catadioptric system with a Spherical Mirror is presented. In particular, the forward projection is reduced to a 4th order polynomial by determining the reflection point on the Mirror surface through the intersection between a sphere and an ellipse. A matrix format of the implemented models, suitable for fast point clouds handling, is also described. A robust calibration procedure is also proposed and applied to calibrate a catadioptric sensor by determining the Mirror radius and center with respect to the camera

  • catadioptric stereo vision system using a Spherical Mirror
    Procedia structural integrity, 2018
    Co-Authors: Sandro Barone, Paolo Neri, Alessandro Paoli, Armando Viviano Razionale
    Abstract:

    Abstract In the computer vision field, the reconstruction of target surfaces is usually achieved by using 3D optical scanners assembled integrating digital cameras and light emitters. However, these solutions are limited by the low field of view, which requires multiple acquisition from different views to reconstruct complex free-form geometries. The combination of Mirrors and lenses (catadioptric systems) can be adopted to overcome this issue. In this work, a stereo catadioptric optical scanner has been developed by assembling two digital cameras, a Spherical Mirror and a multimedia white light projector. The adopted configuration defines a non-single viewpoint system, thus a non-central catadioptric camera model has been developed. An analytical solution to compute the projection of a scene point onto the image plane (forward projection) and vice-versa (backward projection) is presented. The proposed optical setup allows omnidirectional stereo vision thus allowing the reconstruction of target surfaces with a single acquisition. Preliminary results, obtained measuring a hollow specimen, demonstrated the effectiveness of the described approach.

Boris Blinov - One of the best experts on this subject based on the ideXlab platform.

  • Trapped ion imaging with a high numerical aperture Spherical Mirror
    Journal of Physics B: Atomic Molecular and Optical Physics, 2009
    Co-Authors: Gang Shu, Matthew Dietrich, Nathan Kurz, Boris Blinov
    Abstract:

    Efficient collection and analysis of trapped ion qubit fluorescence is essential for robust qubit state detection in trapped ion quantum computing schemes. We discuss simple techniques of improving photon collection efficiency using high numerical aperture (N.A.) reflective optics. To test these techniques we placed a Spherical Mirror with an effective N.A. of about 0.9 inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate stable and reliable trapping of single barium ions, in excellent agreement with our simulations of the electric field in this setup. While a large N.A. Spherical Mirror introduces significant Spherical aberration, the ion image quality can be greatly improved by a specially designed aspheric corrector lens located outside the vacuum system. Our simulations show that the Spherical Mirror/corrector design is an easy and cost-effective way to achieve high photon collection rates when compared to a more sophisticated parabolic Mirror setup.

  • Improving Ion Fluorescence Collection by Integrating High Numerical Aperture Spherical Mirror into Ion Trap
    Frontiers in Optics 2009 Laser Science XXV Fall 2009 OSA Optics & Photonics Technical Digest, 2009
    Co-Authors: Gang Shu, Matthew Dietrich, Nathan Kurz, Boris Blinov
    Abstract:

    We integrated a high N.A. Spherical Mirror into a Paul trap and improved its image by special aspheric correctors. We designed a trap based on metallic Spherical Mirror which greatly increases the ion-photon/ion-ion entanglement efficiency.