Comparison of selected ultrasound performance tests with varying overall receiver gain and dynamic range, using conventional and magnified field of view

1998 ◽  
Vol 25 (5) ◽  
pp. 642-647 ◽  
Author(s):  
Kalpana M. Kanal ◽  
James M. Kofler ◽  
Debra S. Groth
Keyword(s):  
Dynamic Range ◽  
Field Of View ◽  
Performance Tests

scholarly journals Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

2011 ◽  
Vol 28 (1) ◽  
pp. 46-57 ◽  
Author(s):  
B. Pindor ◽  
J. S. B. Wyithe ◽  
D. A. Mitchell ◽  
S. M. Ord ◽  
R. B. Wayth ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Dynamic Range ◽  
Low Frequency ◽  
Neutral Hydrogen ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Field Of View ◽  
Bright Point ◽  
Line Of Sight ◽  
Diffuse Background

AbstractBright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2—3 orders of magnitude.

scholarly journals Non-Intrusive Luminance Mapping via High Dynamic Range Imaging and 3-D Reconstruction

2021 ◽  
Vol 2042 (1) ◽  
pp. 012113
Author(s):  
Michael Kim ◽  
Athanasios Tzempelikos
Keyword(s):  
Dynamic Range ◽  
Low Cost ◽  
High Dynamic Range ◽  
Field Of View ◽  
High Dynamic Range Imaging ◽  
3D Space ◽  
Short Video ◽  
High Dynamic ◽  
Daylighting Control ◽  
Good Agreement

Abstract Continuous luminance monitoring is challenging because high-dynamic-range cameras are expensive, they need programming, and are intrusive when placed near the occupants’ field-of-view. A new semi-automated and non-intrusive framework is presented for monitoring occupant-perceived luminance using a low-cost camera sensor and Structure-from- Motion (SfM)-Multiview Stereo (MVS) photogrammetry pipeline. Using a short video and a few photos from the occupant position, the 3D space geometry is automatically reconstructed. Retrieved 3D context enables the back-projection of the camera-captured luminance distribution into 3D spaces that are in turn re-projected to occupant-FOVs. The framework was tested and validated in a testbed office. The re-projected luminance field showed with good agreement with luminance measured at the occupant position. The new method can be used for non-intrusive luminance monitoring integrated with daylighting control applications.

scholarly journals A Multi-Frequency VLBI Polarization Study of the CSS Quasar 3C 309.1

1998 ◽  
Vol 164 ◽  
pp. 105-106
Author(s):  
Scott E. Aaron ◽  
John F.C. Wardle ◽  
David H. Roberts
Keyword(s):  
Radio Source ◽  
Dynamic Range ◽  
Ambient Medium ◽  
High Dynamic Range ◽  
Field Of View ◽  
Large Field ◽  
General Properties ◽  
Polarization Study ◽  
Rotation Measure ◽  
High Dynamic

AbstractWe discuss the rotation measure properties of the CSS quasar 3C 309.1, determined from high dynamic range, large field of view VLBA images at several frequencies between 1.4 and 15 GHz. We consider the general properties of the ambient medium by considering the structure of the Faraday screen across various parts of the radio source.

The Australia Telescope — Current Status

1985 ◽  
Vol 6 (1) ◽  
pp. 101-104 ◽  
Author(s):  
J . R. Forster
Keyword(s):  
Time Resolution ◽  
Dynamic Range ◽  
Site Preparation ◽  
Field Of View ◽  
Antenna Design ◽  
Current Status ◽  
Full Attention ◽  
Feed Horns ◽  
Compact Array

AbstractThe design of the Australia Telescope is discussed, particularly in reference to the compact array, the frequency ranges of operation, the field of view, dynamic range, polarization, bandwidth, correlators, time resolution and flexibility. Site preparation at Culgoora, antenna design, reflector panel construction, feed horns, receivers an cryogenics, and computing are receiving full attention.

scholarly journals Photometry of Galaxies on Kiso Schmidt Plates

1995 ◽  
Vol 148 ◽  
pp. 419-427
Author(s):  
Takashi Ichikawa
Keyword(s):  
Dynamic Range ◽  
Careful Analysis ◽  
Field Of View ◽  
Large Field ◽  
Clusters Of Galaxies ◽  
Surface Photometry ◽  
Local Universe

AbstractIn spite of the lower S/N and smaller dynamic range of photographic plates compared to those of CCD data, Schmidt plates still have the advantage of a large field of view, which allows us to study the structure of nearby large galaxies and clusters of galaxies. Investigating the internal and external errors of our surface photometry, we show that a careful analysis of photographic plates results in reliable surface photometry data comparable to CCD data for galaxies brighter than ∼ 17 mag. Recent studies based on photographic surface photometry catalogues obtained from Kiso Schmidt plates are reviewed and it can be shown that surface photometry of galaxies on Schmidt plates is still useful for understanding the local universe.

scholarly journals A Simply Equipped Fourier Ptychography Platform Based on an Industrial Camera and Telecentric Objective

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4913
Author(s):  
Shaohui Zhang ◽  
Guocheng Zhou ◽  
Ying Wang ◽  
Yao Hu ◽  
Qun Hao
Keyword(s):  
Phase Retrieval ◽  
Dynamic Range ◽  
Numerical Aperture ◽  
Complementary Metal Oxide Semiconductor ◽  
Computational Imaging ◽  
Field Of View ◽  
Oxide Semiconductor ◽  
Imaging Method ◽  
Wide Field ◽  
Wide Field Of View

Fourier ptychography microscopy (FPM) is a recently emerged computational imaging method, which combines the advantages of synthetic aperture and phase retrieval to achieve super-resolution microscopic imaging. FPM can bypass the diffraction limit of the numerical aperture (NA) system and achieve complex images with wide field of view and high resolution (HR) on the basis of the existing microscopic platform, which has low resolution and wide field of view. Conventional FPM platforms are constructed based on basic microscopic platform and a scientific complementary metal–oxide–semiconductor (sCMOS) camera, which has ultrahigh dynamic range. However, sCMOS, or even the microscopic platform, is too expensive to afford for some researchers. Furthermore, the fixed microscopic platform limits the space for function expansion and system modification. In this work, we present a simply equipped FPM platform based on an industrial camera and telecentric objective, which is much cheaper than sCMOS camera and microscopic platform and has accurate optical calibration. A corresponding algorithm was embedded into a conventional FP framework to overcome the low dynamic range of industrial cameras. Simulation and experimental results showed the feasibility and good performance of the designed FPM platform and algorithms.

Mobile AR Performance Issues in a Cultural Heritage Environment

2018 ◽  
Vol 9 (1) ◽  
pp. 15-31
Author(s):  
Anabela Marto ◽  
A Augusto Sousa
Keyword(s):  
Augmented Reality ◽  
Cultural Heritage ◽  
Field Of View ◽  
Controlled Environment ◽  
Performance Tests ◽  
Augmented Reality System ◽  
Technological Advances ◽  
Mobile Ar ◽  
And Performance

Due to technological advances, augmented reality has seen fast growth in the last decades and numerous implementations of this technology have been in favour for a consequent growth of popularity. For this article, an augmented reality system is implemented for smartphone and tested in a cultural heritage environment to evaluate the system performance in the context. In the first stage, several prototypes were developed, and performance tests were executed in a controlled environment to select a solution to implement and evaluate in-situ. The solution found is a marker-based system, held with Vuforia SDK. When the marker is lost for being outside of the field of view, the system will be based on natural features to accomplish user tracking. Visitors from a cultural heritage space – the Roman Ruins of Conimbriga – tested the app and evaluated it. They considered that the presented system should be implemented in the referred cultural space, as well as in other archaeological spaces.

scholarly journals Freeform Mirror Design for Novel Laser Warning Receivers and Laser Angle of Incidence Sensors

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2569
Author(s):  
Jacek Wojtanowski ◽  
Marcin Jakubaszek ◽  
Marek Zygmunt
Keyword(s):  
Cross Section ◽  
Dynamic Range ◽  
Numerical Aperture ◽  
Merit Function ◽  
Point Of View ◽  
Field Of View ◽  
Stray Light ◽  
Angle Of Incidence ◽  
Detector Position ◽  
Main Challenge

In this paper, we present a novel configuration of an optical angle-of-incidence (AOI) sensor based on the application of a freeform mirror. The main challenge in designing this mirror was to provide a strictly linear transformation between AOI and the spatial position of the spot created on the linear detector array. Another two goals of this paper were to minimize stray light issues (improve the dynamic range) and create an intermediate focus and lateral shift in the detector position with respect to the plane of incidence. From an optical point of view, the designed mirror can thus be understood as the composition of three components: a high-numerical-aperture (NA) fully achromatic f-theta lens in one cross-section and a perfectly focusing lens, combined with a deviating prism in the second (orthogonal) cross-section. In comparison to the standard “shade” methods, the proposed approach allows a constant angular resolution to be maintained over the entire field of view. The mirror was designed on the basis of fundamental geometrical rules by numerically solving differential problems using an innovative scheme based on the minimization of the specific merit function. The proposed method was practically applied to design a freeform mirror for a 90°/120° field-of-view sensor, showing a satisfactory performance.

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