Showing papers on "Zone plate published in 1976"

Zone plate alignment marks

Abstract: Certain classes of patterns, for example so-called zone plates, are utilized as alignment marks in the fabrication of integrated circuits. Such a plate, which functions as a lens, provides a high-brightness image that is relatively insensitive to any degradation of the pattern.

Formation of hologram

Abstract: PURPOSE: To eliminate astigmatism and image distorsion, even if the wave fronts are made different upon formation and reproduction of FZP (Fresnel Zone Plate), by making plane waves incident at an angle upon the surface of a photosensitive material while fixing the angle between the plane waves and spherical waves COPYRIGHT: (C)1978,JPO&Japio

Phase compensated zone plate photodetector

Abstract: A radiation transparent base having a number of coincentric Fresnel rings mounted on one face, and one-quarter wavelength in thickness and a reflective coating covering the face and rings and a detector mounted on the opposite face to collect reflected in phase radiation

X-ray focal spot test system

Abstract: An X-ray system comprising an X-ray tube provided with a target focal spot area from which an X-ray beam emanates from the tube, an X-ray Fresnel zone plate disposed interceptingly in the path of the X-ray beam, and an image receptor disposed to receive the resulting image of the zone plate conveyed by the X-ray beam.

Fresnel zone plate: Anomalous foci

Abstract: It is found that, when a zone plate is examined in practice, foci exist where there should be none. An approach is developed which reveals that the zone plate is a circular diffraction grating, which in turn explains how a hologram works in a very direct manner.

Comparisons of coded aperture imaging using various apertures and decoding methods

Abstract: The utility of coded aperture imaging of radioisotope distributions in Nuclear Medicine is in its ability to give depth information about a three dimensional source. We have calculated imaging with Fresnel zone plate and multiple pinhole apertures to produce coded shadows and reconstruction of these shadows using correlation, Fresnel diffraction, and Fourier transform deconvolution. Comparisons of the coded apertures and decoding methods are made by evaluating their point response functions both for in-focus and out-of-focus image planes. Background averages and standard deviations were calculated. In some cases, background subtraction was made using combinations of two complementary apertures. Results using deconvolution reconstruction for finite numbers of events are also given.

Digital Imaging of Gamma-Ray Sources with Depth Information

Abstract: A digital method for imaging gamma-ray emitting organs recorded through a Fresnel zone plate (FZP) aperture is described. This technique can be used in an almost real-time recording and imaging system to yield quantitative and qualitative cross-section and depth information of the source. Furthermore, this method avoids some of the problems introduced by the usual method of optical reconstruction. Experimental results of the recording of a multiplane gamma-ray source and the reconstruction of digitally and optically formed images are also presented.

An on-axis Fresnel zone plate imaging system with a germanium gamma ray camera and computer reconstruction /

Abstract: 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete.

Image Reconstruction Of Multiplane Gamma-Ray Sources With A Fresnel Zone Plate Aperture

Abstract: A process is described for digitally reconstructing images of gamma-ray emitting organs recorded through an off-axis Fresnel zone plate aperture. This technique produces image cross sections for given depths which contain both quantitative and qualitative information about the source. The practicality of digital decoding is demonstrated experimentally by comparing the digital and optical reconstructions of images of a multi-plane gamma-ray source. Specifically, the multiplane source consists of numerals one, two and three located in three distinct planes at successive depths from the detector. The digital method of reconstruction has the following advantages over a method employing optical reconstruction. A quasi-real time system capable of recording and producing images can be assembled using components currently available. Quantitative data such as the source size and depth are readily determined. Digital image processing can be easily implemented to reduce the effect of artifacts and noise. Unlike the case using optical re-construction, the image depth dimension is not distorted in comparison with the source depth. Nonlinearity and film noise associated with the photographic process of obtaining a reduced transparency are avoided.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Digital Imaging ofGamma-RaySources withDepthInformation

Abstract: A digital methodforimaging gamma-ray emitting organs recorded through a Fresnel zone plate(FZP)aperture isdescribed. Thistechnique canbeusedinanalmost real-time recording andimaging system toyield quantitative andqualitative cross-section anddepthin- formation ofthesource.Furthermore, this methodavoids some ofthe problems introduced bytheusual methodofoptical reconstruction. Experimental results oftherecording ofamultiplane gamma-ray source andthereconstruction ofdigitally andoptically formed images arealso presented.