نتایج جستجو برای: silver pinhole

تعداد نتایج: 47177  

Journal: :Optics letters 2003
Hugo F Schouten Greg Gbur Taco D Visser Emil Wolf

We analyze the coherence properties of a partially coherent field emerging from two pinholes in an opaque screen and show that the spectral degree of coherence possesses phase singularities on certain surfaces in the region of superposition. To our knowledge, this is the first illustration of the singular behavior of the spectral degree of coherence, and the results extend the field of singular...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 1980
D L Williams J L Ritchie G D Harp J H Caldwell G W Hamilton

Seven-pinhole emission tomography has been studied under conditions that simulate clinical myocardial imaging with thallium-201, and is compared with planar imaging with a heart phantom. The seven-pinhole technique produces reconstructed images that offer a tomographic presentation of the object but do not quantitatively represent true cross sections of the object's activity distribution. Tomog...

Journal: :Medical physics 2012
Da Zhang Xinhua Li Bob Liu

PURPOSE This paper presents new spectral measurements of a tungsten-target digital breast tomosynthesis (DBT) system, including spectra of 43-49 kVp. METHODS Raw x-ray spectra of 20-49 kVp were directly measured from the tube port of a Selenia Dimensions DBT system using a CdTe based spectrometer. Two configurations of collimation were employed: one with two tungsten pinholes of 25 μm and 200...

2001
S S Harilal

Soft x-ray emission from plasmas produced by ablation from a magnesium target employing a ruby laser is studied using a grazing incidence spectrograph in the spectral region 3–12 nm. Emission intensities are investigated for different ionic lines as a function of position, time after the maximum of the laser pulse and laser irradiance. A gated pinhole camera is employed for studying the evoluti...

2009
James Coughlan

where c is the column and r is the row. (This is a Point Grey convention, and it assumes the camera center is exactly in the center column and row of the image. In fact, proper camera calibration can be done to get a better estimate of the center.) The (X,Y,Z) coordinate system is shown in Fig. 1, and the (u, v) system in Fig. 2: Z points along line of sight, away from camera; X (and also u) po...

Journal: :IEEE transactions on nuclear science 2002
L J Meng W L Rogers N H Clinthorne

This paper presents a feasibility study of a Compton scattering enhanced (CSE) multiple pinhole imaging system for gamma rays with energy of 140keV or higher. This system consists of a multiple-pinhole collimator, a position sensitive scintillation detector as used in standard Gamma camera, and a Silicon pad detector array, inserted between the collimator and the scintillation detector. The pro...

Journal: :Optics express 1998
J Fessler

This paper analyzes the tradeo between spatial resolution and noise for simple pinhole imaging systems with photon-counting detectors. We consider image recovery algorithms based on density estimation methods using kernels that are based on apodized inverse filters. This approach allows a continuous-object, continuous-data treatment of the problem. The analysis shows that the pinhole size that ...

Journal: :Optics letters 2008
Daryl Lim Kengyeh K Chu Jerome Mertz

We introduce an application of thermionic emission in a PMT photocathode. Because of the nonlinear dependence of thermionic emission on absorbed laser power, a conventional PMT is found to produce a virtual pinhole effect that rejects unfocused light at least as strongly as a physical pinhole. This virtual pinhole effect is exploited in a scanning transmission confocal microscope equipped with ...

2018
Sachiko Udagawa Shinji Ohkubo Aiko Iwase Yuto Susuki Shiho Kunimatsu-Sanuki Takeo Fukuchi Chota Matsumoto Yuko Ohno Hiroshi Ono Kazuhisa Sugiyama Makoto Araie

PURPOSE Traffic accidents are associated with the visual function of drivers, as well as many other factors. Driving simulator systems have the advantage of controlling for traffic- and automobile-related conditions, and using pinhole glasses can control the degree of concentric concentration of the visual field. We evaluated the effect of concentric constriction of the visual field on automobi...

Journal: :The Review of scientific instruments 2016
A B Zylstra H-S Park J S Ross F Fiuza J A Frenje D P Higginson C Huntington C K Li R D Petrasso B Pollock B Remington H G Rinderknecht D Ryutov F H Séguin D Turnbull S C Wilks

Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 2...

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