Showing papers on "Zone plate published in 1975"
TL;DR: The annulus is intermediate between the pinhole and the Fresnel zone plate with regard to both collection efficiency and the number of counts required for a given signal-to-noise ratio (SNR) and offers an improvement over pinhole apertures without demanding the increased count rate and resolution required of detectors when Fresnel Zone plate coded aperture are used.
Abstract: In the past, annular coded aperture images have been recon-structed by correlating an appropriately scaled annulus with the coded image. The basic improvement suggested in this paper is the addition of a linear radial frequency weighting in the Fourier plane. Reconstructions of point and disk objects were simulated with a computer program. The results show the advantage of this modification in the processing scheme. When the assumption is made that the detector is an Anger camera, the resolution obtained with the improved processing of the coded image is equal to that obtained with conventional apertures. An actual object consisting of the letter E was imaged with an annular aperture and a scintillation camera. The reconstruction with and without the improved processing is presented. In addition, the annulus is intermediate between the pinhole and the Fresnel zone plate with regard to both collection efficiency and the number of counts required for a given signal-to-noise ratio (SNR). It therefore offers an improvement over pinhole apertures without demanding the increased count rate and resolution required of detectors when Fresnel zone plate coded apertures are used.
27 citations
Book•
01 Oct 1975
TL;DR: In this article, the authors present a detailed analysis of the fundamental wave properties of Holograms and their application in a variety of applications, including the following: 1) Wave Coherence, 2) Wave Interference, 3) Wave Visualization, 4) Spatial Coherence and 5) Coherent Waves from Small Sources.
Abstract: 1 Fundamental Wave Properties- 11 Wave Interference- 12 Phase- 13 Wave Visualization- 14 Diffraction- 15 Diffraction by a Slit- 16 The Near (Fresnel), Far (Fraunhofer), and Transition Fields- 17 Diffraction by Two Slits- 18 Dependence of Diffraction on Wavelength- 19 Wave Polarization- 110 Refraction- 111 Prisms- 112 References- 2 Wave Coherence- 21 Frequency Coherence- 22 Frequency Stability- 23 Spatial Coherence- 24 Coherent Waves from Small Sources- 25 The Extremely Short Wavelengths of Light- 3 Gratings and Zone Plates- 31 The Optical Grating- 32 Slit Gratings and Photographic Gratings- 33 A Prism Grating- 34 A Double-Prism Grating- 35 Volume Effects- 36 The Classical Zone Plate- 37 Zone Plates with Areas Interchanged- 38 A Photographic Zone Plate- 39 Offset Zone Plates- 310 Zone Plates as Lenses- 311 Volume Zone Plates- 312 Standing-Wave Patterns- 313 Lattice Reflectors- 314 Reflection Zone Plates- 315 References- 4 Hologram Fundamentals- 41 Two Simple Holograms- 42 The Complete Hologram Process- 43 The Hologram of a Scene- 44 Parallax in Holograms- 45 Single-Wavelength Nature of Holograms- 46 Nonoptical Holograms- 47 Microwave Holograms- 48 Acoustic Holograms- 49 Microwave Holograms and Liquid Crystals- 410 Liquid-Surface Acoustic Holograms- 411 Hologram Equations- 412 References- 5 Properties of Holograms- 51 Three-Dimensional Realism- 52 Holograms and Photographs- 53 Lens Action- 54 A Stereohologram- 55 Focused-Image Holography- 56 Reconstruction with a Small Portion of a Hologram- 57 Pseudoscopy in the Real Image of a Hologram- 58 Image Inversion- 59 Color Holograms- 510 Requirements on Film Properties- 511 Information Content- 512 Holograms and Coherent Radar- 513 References- 6 Laser Fundamentals- 61 The Metastable State- 62 The Two-Step Process- 63 Energy Conservation with Reflectors- 64 Reflectors and Spatial Coherence- 65 Energy Concentration- 66 Q-Spoiling- 67 Gas Lasers- 68 Reflectors and Resonators- 69 The Natural Line Width- 610 Coherence Length- 611 Semiconductor Lasers- 612 Other-Level Lasers- 613 References- 7 Recent Developments in Lasers- 71 Laser Units- 72 Solid Lasers- 73 Solid Laser Amplifiers- 74 Gas Lasers- 75 Semiconductor Lasers- 76 Liquid Lasers- 77 Mode Locking- 78 References- 8 Lasers in Measurement- 81 Alignment- 82 Distance and Length Measurements- 83 Velocity Measurements- 84 Measurement of Acceleration- 85 Atmospheric Effects- 86 Sonic Boom- 87 Measurement of Pollutants- 88 Lasers in Machine-Tool Measurements- 89 Holographic Microscopy- 810 Saturation Spectroscopy- 811 Raman and Brillouin Spectroscopy- 812 Mass Spectroscopy- 813 Holographic Interferometry- 814 Interferometric Structure Analysis- 815 Interferometric Detection of Footprints- 816 Interferometric Testing of Rocket Components- 817 Nonoptical Holographic Interferometry- 818 Laser Speckle- 819 Measurement Techniques Employing Speckle- 820 References- 9 Microwave Holography- 91 Early Developments- 92 Detection Devices- 93 Microwave-Hologram Antennas- 94 Liquid Crystal Holograms- 95 Holographic Signal Processing- 96 The Synthetic-Aperture Concept- 97 Stationary Synthetic-Aperture Systems- 98 Forward-Scatter Hologram Radars- 99 Bistatic Hologram Radars- 910 Passive and End-Fire Radars- 911 Synthetic-Interferometer Radars- 912 Radar Range Acquisition by Holography- 913 References- 10 Acoustic Holography Applications- 101 Early Developments- 102 Acoustic Synthetic-Aperture Systems- 103 Underwater Applications- 104 Acoustic Kinoforms- 105 Holographic Pulse Compression- 106 Hologram Sonar Using Incoherent Illumination- 107 Seismic Holography- 108 References- 11 Lasers in Industry- 111 Welding and Metalworking- 112 Micromachining- 113 Solid-State Trimming- 114 Laser Scribers for Substrates- 115 Microdrilling- 116 Fabric Cutting- 117 Checkout Systems for Supermarkets- 118 Display Applications- 119 Cable Insulation Stripping- 1110 Control of Crystal Growth- 1111 Chromatograph-Analysis Use- 1112 Weather Analysis- 1113 References- 12 Communications- 121 The Constant Demand for Bandwidth- 122 Coaxial Cable- 123 Microwave Systems- 124 Radio Relay Circuits- 125 Satellite Communications- 126 Orbiting Satellites- 127 Synchronous Satellites- 128 Domestic Systems- 129 Early Laser Research- 1210 Basic Laser Communication Considerations- 1211 Line-of-Sight Laser Communications- 1212 Satellite Laser Communications- 1213 Wires of Glass- 1214 A Long-Distance Fiber Circuit- 1215 Short-Length Fiber Circuits- 1216 Optical Film Devices- 1217 Lasers in Microfilm Transmission- 1218 Television Recording- 1219 References- 13 Medical Applications- 131 The Development of Ultrasonics in Medical Imaging- 132 Recent Developments- 133 Details of Recent Ultrasonic Techniques- 134 Synthetic-Aperture Techniques in Medicine- 135 Real-Time Synthetic Aperture- 136 Liquid-Surface Holography for Medical Diagnostics- 137 Concern About Acoustic Intensity in Holography- 138 Holography and Three-Dimensional X-Ray Pictures- 139 Holography and Three-Dimensional Gamma-Ray Images- 1310 Applications in Ophthalmic Fields- 1311 Dental Applications- 1312 References- 14 Computing Applications- 141 Fourier Series- 142 Discrete Fourier Analysis- 143 Discrete Analysis Tables- 144 Fourier Integrals- 145 Fourier Transforms- 146 Fast Fourier Transforms (FFT)- 147 Distant-Field Patterns- 148 Near-Field Patterns- 149 Space-Frequency Equivalence- 1410 Two-Dimensional Fourier Transforms- 1411 The History of Optical Processing- 1412 Optical Filtering- 1413 Seismic Applications- 1414 Complex Optical Filters- 1415 Complex-Filter Applications- 1416 Optical Processing in Radar- 1417 Parallel Optical Processing: The Accepting Function- 1418 Parallel Optical Processing: The Processing and Display Function- 1419 Real-Time Optical Computing- 1420 Computer-Generated Holograms- 1421 Holographic Computer Memories- 1422 Flying-Spot Scanning- 1423 Read-Only Memories- 1424 Volume Hologram Memories- 1425 Erasable Memories- 1426 One-Dimensional Hologram Memories- 1427 References- 15 Nuclear Fusion- 151 Power Needs- 152 Atomic Energy Development- 153 Nuclear Weapons- 154 Fission Reactors- 155 The Breeder Reactor- 156 Controlled Fusion- 157 Amplifying the Laser Pulses- 158 Laser-Fusion Experiments- 159 Pulse Tailoring- 1510 Uranium Enrichment by Lasers- 1511 References- Further Reading Suggestions- Author Index
22 citations
TL;DR: The autocorrelation method can give a gain of 50% in signal-to-noise for a single point source over the maximum obtainable with optical decoding.
Abstract: Zone plate cameras are used for high sensitivity imaging of X- and gamma -ray sources. The image thus obtained requires decoding and numerical techniques are devised for this purpose. The response function and the signal-to-noise ratio for a single point source have been evaluated for zone plates with varying numbers of zones. Autocorrelation is the best of the methods examined, and the results are in good agreement with those obtained using Monte Carlo techniques. The autocorrelation method can give a gain of 50% in signal-to-noise for a single point source over the maximum obtainable with optical decoding. Criteria for the choice of number of zones are discussed.
18 citations
01 Jan 1975
TL;DR: In this article, a phase plate pattern of appropriate design was used as one electrode on a disk transducer to focus volume acoustic waves in sapphire rods at frequencies near 10 MHz.
Abstract: Fresnel zone plates have long been used in the field of classical optics and more recently have had applications in such varied fields as gamma ray imaging1 and laser micro machining.2 Acoustic applications have been investigated at frequencies of I.5 GHz, where zone plates were used to focus volume acoustic waves in sapphire rods3 We have recently begun exploring the use of zone plates to focus sound in water at frequencies near 10 MHz. Our original approach to this problem was to use a zone plate pattern of appropriate design as one electrode on a disk transducer.4 We have found however, that the performance of these devices may be greatly enhanced by converting them to acoustic Rayleigh-Wood phase-reversal zone plates,5 or acoustic phase plates. We shall describe how this conversion is easily effected through the use of a simple poling procedure. Our imaging system, the heart of which is this phase plate transducer, has resolution capabilities of 0.27 mm or approximately 1.8 wavelengths. Images have been obtained in both transmission and reflection modes.
18 citations
TL;DR: A theoretical model that explains both interferometers is developed and suggests the fruitful applications of holography to this branch of optics.
Abstract: A new interferometric method for testing optical surfaces is given. It is related to Murty's Fresnel zone plate interferometer and suggests the fruitful applications of holography to this branch of optics. In this paper a theoretical model that explains both interferometers is developed. Experimental results and pertinent comments are included.
17 citations
Patent•
30 May 1975TL;DR: In this paper, a nuclear imaging system in which a substantially on-axis Fresnel zone plate positioned between a source of nuclear radia-tion in living tissue and a spatial detector is moved in a pre-determined time sequence in synchronism with motion of a bar pattern formed at the spatial detector output to improve suppres-sion of unwanted spatial frequency components and to facilitate production of an image of the nuclear source is described.
Abstract: COED IMAGING SYSTEMS Abstract of the Disclosure A nuclear imaging system in which a substantially on-axis Fresnel zone plate positioned between a source of nuclear radia-tion in living tissue and a spatial detector is moved in a pre-determined time sequence in synchronism with motion of a bar pattern formed at the spatial detector output to improve suppres-sion of unwanted spatial frequency components and to facilitate production of an image of the nuclear source.
15 citations
Patent•
3M1
TL;DR: In this paper, a reflective material is made by recording an array of photoreduced images of an original geometric fresnel zone plate image in a photosensitive medium; using the developed photo-sensitive medium to make a stamper for embossing an array modulated phase modulated Fresnel zone plates corresponding to the photorescribed images; and coating a reflective materials on the opposite surface of the copy medium.
Abstract: Retroreflective material is made by recording an array of photoreduced images of an original geometric fresnel zone plate image in a photosensitive medium; using the developed photosensitive medium to make a stamper for embossing an array of phase modulated fresnel zone plates corresponding to the photoreduced images; using the stamper to emboss such fresnel zone plates in a transparent copy medium having a thickness equal to a given focal length associated with such fresnel zone plates to provide an array of such fresnel zone plates at one surface of the copy medium; and coating a reflective material on the opposite surface of the copy medium.
11 citations
TL;DR: Using an Anger gamma camera and a zone plate aperture both a line source and a thyroid phantom containing 99Tcm have been well reconstructed and the behaviour of the system with regard to resolution, signal-to-noise ratio and tomographic capability is discussed.
Abstract: A method for the digital decoding of data obtained with a gamma camera fitted with a zone plate aperture is described. Taking a line source as the object, computer simulations have been used to examine the effects of noise, solid angle variations, shape of detector and detector resolution and methods of dealing with these effects are considered. Using an Anger gamma camera and a zone plate aperture both a line source and a thyroid phantom containing 99Tcm have been well reconstructed. The behaviour of the system with regard to resolution, signal-to-noise ratio and tomographic capability is discussed.
10 citations
Journal Article•
TL;DR: First clinical studies with a Fresnel zone-plate radioisotope imager demonstrate high resolution, sharp tomography, and freedom from scatter, at least for small organs like the thyroid.
Abstract: First clinical studies with a Fresnel zone-plate radioisotope imager demonstrate high resolution, sharp tomography, and freedom from scatter. Improved radionuclide imaging is demonstrated, at least for small organs like the thyroid. Certain limitations are present that indicate a need for additional development before application to routine clinical practice.
10 citations
TL;DR: In this paper, a detailed analysis is made of the moire pattern formed on superposing a Fresnel zone plate with an equispaced grating or a rectangular grid, and information regarding the focal length, location and phase of the Moire zone plates so produced is extracted.
Abstract: A detailed analysis is made of the moire pattern formed on superposing a Fresnel zone plate with an equispaced grating or a rectangular grid. Information regarding the focal length, location and phase of the moire zone plates so produced is extracted. The relevance of this work to a number of physical situations is discussed.
TL;DR: In this article, a Fourier-series representation of a Fresnel zone plate is set up and used, with a paraxial approximation, to predict features of the image-forming and Fouriertransforming properties of the plate.
Abstract: A Fourier-series representation of a Fresnel zone plate is set up and used, with a paraxial approximation, to predict features of the image-forming and Fourier-transforming properties of the plate. These properties are compared and contrasted with those of a lens, and examples of a Fraunhofer diffraction pattern from a plate and a lens are illustrated.
TL;DR: In this article, the use of holograms as zone plates is explained and it is shown that under certain conditions such a zone plate can be made aplanalic, i.e. free from spherical aberration and coma, and the design procedure is indicated.
Abstract: The use of holograms as zone plates is explained. It is shown that under certain conditions such a zone plate can bc made aplanalic, i.e. free from spherical aberration and coma, and the design procedure is indicated.
TL;DR: In this article, the image contrast is experimentally demonstrated to be a particular function of various parameters including the area of the source divided by the central Fresnel zone, and the best fit parameters are reported.
TL;DR: In this article, an expression for the field of a light pulse of initially arbitrary shape with initially Gaussian intensity distribution in the cross section which traversed a lens and a zone plate was derived.
Abstract: An expression is derived for the field of a light pulse of initially arbitrary shape with initially Gaussian intensity distribution in the cross section which traversed a lens and a zone plate. Temporary variations of the pulse shape and duration in the area of an arbitrary-order focus are investigated. Variations in the shape of an electromagnetic package without high-frequency filling in the diffraction process are also studied. The relief of the two-photon luminescence track for focused and unfocusd counterflows is theoretically investigated and shown to qualitatively differ in cases of a single pulse and a train of incident pulses. Therefore, a lens and zone plate focusing can be applied for estimating sufficiently short light pulse durations and the time interval between them.
01 Jan 1975
TL;DR: In this article, the authors proposed a two-step imaging process called coded aperture imaging (Coded aperture imaging), where each point in the object encodes its 3D location by casting a shadow of a Fresnel zone plate onto a photographic plate.
Abstract: ”Coded aperture imaging” is a recently agreed-upon name (1) for a two-step imaging process conceived in the early 1960’s by Mertz and Young (2, 3, 4, 5) at Block Engineering. Their basic idea was to let each point in the object encode its three-dimensional location by casting a shadow of a Fresnel zone plate onto a photographic plate. Thus an object consisting of a collection of points would be encoded as a collection of zone plates. Lateral displacement of the object points leads to lateral displacement of the shadow-cast zone plates. Vertical displacement of the object points leads to scale changes in the shadow-cast zone plates. Given this encoded image, it is easy to arrive at an image. Illumination with coherent light converts each zone plate into a point. The lateral position of the decoded point is determined by the lateral position of the corresponding zone plate. The vertical position of each decoded point is determined by the scale of the corresponding zone plate. Thus the three - dimensional image encoded by shadow casting can be decoded by illumination with coherent light.