Search results for "Computer Vision"
showing 10 items of 2353 documents
Axial resonance of periodic patterns by using a Fresnel biprism.
2013
This paper proposes a method for the generation of high-contrast localized sinusoidal fringes with spatially noncoherent illumination and relatively high light throughput. The method, somehow similar to the classical Lau effect, is based on the use of a Fresnel biprism. It has some advantages over previous methods for the noncoherent production of interference fringes. One is the flexibility of the method, which allows the control of the fringe period by means of a simple axial shift of the biprism. Second is the rapid axial fall-off in visibility around the high-contrast fringe planes. And third is the possibility of creating fringes with increasing or with constant period as the light bea…
Analytical description of lobster eye and similar multi-foil optics
2015
Analytical equations describing lobster eye optical parameters on dependence on its geometric parameters are presented. The paper partially gives review of main previously known results. At next, the paper gives new results discussing parameters, that were not included to previously published models but may be significant. The results are applicable for a Schmidt as well as for an Angel lobster eye and for some related multi-foil systems.
Realization of a robust single-parameter quantized charge pump
2008
This paper describes a novel scheme for quantized charge pumping based on single-parameter modulation. The device is realized in an AlGaAs-GaAs gated nanowire. A particular advantage of this realization is that operation in the quantized regime can be achieved in a potentially large range of amplitude and dc off-set of the driving signal. This feature together with the simple configuration might enable large scale parallel operation of many such devices.
The optical blocking filter for the ATHENA wide field imager: Ongoing activities towards the conceptual design
2015
ATHENA is the L2 mission selected by ESA to pursue the science theme "Hot and Energetic Universe" (launch scheduled in 2028). One of the key instruments of ATHENA is the Wide Field Imager (WFI) which will provide imaging in the 0.1-15 keV band over a 40'x40' large field of view, together with spectrally and time-resolved photon counting. The WFI camera, based on arrays of DEPFET active pixel sensors, is also sensitive to UV/Vis photons. Optically generated electron-hole pairs may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of an X-ray transparent optical blocking filter is needed to allow the observation of all …
Transversal superresolution with noncontact axial movement of periodic structures
2007
We present an innovative approach that allows superresolved images to be obtained by axial moving of two gratings and time integrating in the detector plane. The two gratings do not have to be in contact with either the object or the detector, and both are positioned between the object and the image planes. One of the main applications for the proposed approach in contrast to previously discussed time multiplexing superresolving methods is that it may fit well to superresolved imaging of remote objects, since both gratings are not in contact with either the object or the detector planes.
Based on Compton Camera
2016
Compton Cameras have been proposed as an alternative to SPECT imaging with Gamma Camera, mainly due to factors such as the electronic collimation, which allows a bigger field of view and provides further information from the acquired events if compared to devices with mechanical collimation. By contrast, this involves a higher amount of data to be processed. In medical devices this leads to waiting times that are generally higher than desirable by the health-care professionals. In this work we have assessed the reconstruction of Compton images by making use of iterative and non-iterative techniques, and also evaluated its performances as a SPECT imaging technique.
A mammographic phantom image reconstruction through Monte Carlo techniques
2005
Mammographic phantoms are employed during quality control test in breast screening locations and other health centres. These quality controls are performed to achieve the image quality required to detect breast abnormalities, ensuring the minimum risk to radiographied women. The aim of this study is the development of a methodology to reproduce the image of a mammogram during a routine exposure in a breast screening programme. In a first step, the CIRS 11A (MAMMO PHANTOM SP01) mammographic phantom has been simplified and modelled with the Monte Carlo transport code MCNP-4c2. Different tallies (F2 and F5) have been used to score the photon flux under the phantom, and a group of aluminium lay…
Compressive single-pixel multispectral Stokes polarimeter
2014
We present a single-pixel system that performs polarimetric multispectral imaging with the aid of compressive sensing techniques. We experimentally obtain the full Stokes spatial distribution of a scene for different spectral channels.
Shape from polarization: a method for solving zenithal angle ambiguity
2012
International audience; We report a multispectral based method that permits the evolution of shape from polarization setup applied to 3D shape estimation of transparent objects. The setup is based on a polarization imaging technique which is a recent imaging method based on the analysis of the polarization state of the light in the observed scene. The technique has rapidly evolved with the development of electro-optic components and some polarization cameras are now available on the market. Shape from polarization consists in measuring the azimuthal and zenithal angles characterizing the normal of each point of the observed surface. We focus on the ambiguity in the measurement of the zenith…
Variable-Radius Offset Surface Approximation on the GPU
2020
Variable-radius offset surfaces find applications in various fields, such as variable brush strokes in 2D and 3D sketching and geometric modeling tools. In forensic facial reconstruction the skin surface can be inferred from a given skull by computing a variable-radius offset surface of the skull surface. Thereby, the skull is represented as a two-manifold triangle mesh and the facial soft tissue thickness is specified for each vertex of the mesh. We present a method to interactively visualize the wanted skin surface by rendering the variable-radius offset surfaces of all triangles of the skull mesh. We have also developed a special shader program which is able to generate a discretized vol…