Journal ArticleDOI
Fresnel zone plate imaging of gamma rays; theory
TLDR
The general theory of coded-aperture imaging is presented, first for an arbitrary code and then for an on-axis zone plate, an off-axis Zone Plate, and a one-dimensional zone plate (or linear chirp).Abstract:
The use of a Fresnel zone plate as a coded aperture for imaging incoherent radiation such as gamma rays has been previously reported. The coded image is in many respects similar to a hologram and can be decoded or reconstructed with a coherent optical system. In this paper, the general theory of coded-aperture imaging is presented, first for an arbitrary code and then for an on-axis zone plate, an off-axis zone plate, and a one-dimensional zone plate (or linear chirp). With the on-axis plate, a matched imaging condition is suggested as a guide to optimizing image contrast. With the off-axis zone plate and the linear chirp, it is necessary to use a half-tone screen to spatially heterodyne the object spectrum into the passband of the aperture. In all three cases, expressions for the resolution, depth of field, field of view, and relative efficiency are derived. A simplified noise analysis is presented, and some practical system constraints are discussed.read more
Citations
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PatentDOI
Coded aperture imaging with uniformly redundant arrays
E. E. Fenimore,Thomas M. Cannon +1 more
TL;DR: Computer simulations show that the URA with significant shot and background noise is vastly superior to random array techniques without noise, and permits a detector which is smaller than its random array counterpart.
Journal ArticleDOI
Coded aperture imaging in X- and gamma-ray astronomy
TL;DR: Coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range from X-to γ-rays and is playing a unique role in those spectral ranges where other techniques become ineffective or impracticable due to limitations connected to the physics of interactions of photons with matter.
Journal ArticleDOI
Uniformly redundant arrays: digital reconstruction methods
E. E. Fenimore,T. M. Cannon +1 more
TL;DR: Several new digital reconstruction techniques for coded aperture imaging are developed which are especially applicable to uniformly redundant arrays (URAs), and it is shown that another new digital technique, periodic decoding, is much faster.
Journal Article
Adaptive SPECT
Harrison H. Barrett,Lars R. Furenlid,M. Freed,Jacob Y. Hesterman,Matthew A. Kupinski,Eric Clarkson,Meredith Kathryn Whitaker +6 more
TL;DR: This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptiveSPECT systems in particular.
Journal ArticleDOI
Analog reconstruction methods for transaxial tomography
TL;DR: Transaxial tomography is a radiographic technique that provides an image of an isolated two-dimensional section of a three-dimensional object as mentioned in this paper, and the equivalence of various mathematical formulations is shown The properties of the resulting image for various filter functions are described and limitations imposed by the quantum statistics of the radiation source are briefly discussed.
References
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Journal ArticleDOI
Reconstructed Wavefronts and Communication Theory
Emmett N. Leith,Juris Upatnieks +1 more
TL;DR: In this paper, a two-step imaging process is described from a communication-theory viewpoint, which consists of three well-known operations: a modulation, a frequency dispersion, and a square-law detection.
Journal ArticleDOI
The theory and design of chirp radars
TL;DR: This paper contains many of the important analytical methods required for the design of a Chirp radar system, and a method to reduce the time side lobes by weighting the pulse energy spectrum is explained in terms of paired echoes.
Journal ArticleDOI
Multi-Slit Spectrometry*
TL;DR: The factors which limit the recording speed and the resolution of infra-red spectra are reviewed, and methods offering increased overall photometric efficiency are examined.
Journal ArticleDOI
Zone Plates and Their Aberrations
TL;DR: In this article, the authors derived the third-order and chromatic aberrations of the zone plate and showed that the image may be diffraction limited only if the illumination is relatively monochromatic.