J E Murray · University of North Texas Digital Library (University of North Texas) · 1996
Experiments and calculations indicate that the threshold pressure in spatial filters for distortion of a transmitted pulse scales approximately as I{sup O.2} and (F{number_sign}){sup 2} over the intensity range from 10{sup 14} to 2xlO{sup 15} W/CM{sup 2} . We also demonstrated an interferometric diagnostic that will be used to measure the scaling relationships governing pinhole closure in spatial filters.
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N. K. Moncur · Applied Optics · 1977
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text N. Kent Moncur, "Plasma spatial filter," Appl. Opt. 16, 1449-1451 (1977) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article
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HIZNY, JOHN J. · Institutional Repository of Xi'an Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (Xian Institute of Optics and Precision Mechanics) · 1991
A monolithic optical device formed from a GRIN rod having a centered aperture at an exit end thereof is bonded to a laser exit face to couple laser radiation through a spatial aperture without the alignment sensitivity characteristic of the prior art by the sequence of fabrication and alignment steps, whereby the output beam from the spatial filter is essentially subject only to vignetting as a result of misalignment of the optic with respect to the laser beam, rather than to the distorted wavefront characteristic of such misalignment in the prior art.
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Silvério P. Almeida, J.K.T. Eu · Applied Optics · 1978
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. P. Almeida and J. K. Tzong Eu, "Rotating wedge spatial filter," Appl. Opt. 17, 163-163 (1978) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article
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Robert R. Kallman · 1995
Abstract : The objective of this program was the design of optical spatial filters. Among the topics discussed in this report are: the proper role of correlation in target recognition and discrimination; noise considerations for the objective function used in designing spatial filters; correct computer modeling of the correlation process; a completely new approach to the design of general spatial filters as a constrained optimization question in all free parameters (all amplitudes and phases); the design of spatial filters whose entries are either zero or a continuous phase as an optimization question; the optimal discretization of spatial filters whose entries are either zero or a continuous phase; the need and sufficiency for spatial filters whose entries are either zero or an nth root of unity; the problems of target(background contrast and target translation invariance with respect to background; intensity phase- encoding of imagery and its advantages; zero-mean intensity phase-encoding of imagery and its advantages in solving the background problems; and a new edge enhancement (binarization procedure based on phase-encoding and local Wigner transforms. A secondary purpose of this document is to be a user guide to the software created during this effort for the design of spatial filters. A goal of this effort nas been a drastic refinement, extension, and extrapolation of spatial filter design codes in the parallel programming language occam 2 for use in inexpensive transputer based parallel processing systems. Spatial filter design on an occam 2/transputer based system is now approximately 250 times faster than on a FORTRAN/Vax system.
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PRICE, R. KIRK, KARLSEN, SCOTT, MARTINSEN, ROB et al. · Institutional Repository of Xi'an Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (Xian Institute of Optics and Precision Mechanics) · 2016
A laser system can include an optical fiber having a spatial filter defined as a core extension coupled to or integrally formed in an optical fiber so as to reduce the coupling of optical radiation into a fiber cladding. Such a core extension can be formed by removing a length of the cladding from the optical fiber, leaving a portion of the core exposed at the end of the fiber. Alternatively, a core extension can be formed by coupling an end cap to the core of the optical fiber at a fiber end surface. By selecting a length of the core extension based on a beam divergence and beam diameter, radiation coupling into the fiber core can be reduced.
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Khalil Seyrafi, G. A. Davison, J. L. Gaston · 1965
Abstract : The report discusses the design and synthesis of lowpass and band-pass one-dimensional and two-dimensional spatial filters using arrays or matrices of detectors. The synthesis was performed for alternate assumptions of negligible and significant detector gaps. The detector width and the detector weighting functions are the two optimized parameters. A frequency analyzer, using a narrow-band one-dimensional filter, was designed and simulated. Tests indicated performance as expected.
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Torsten Möller, Raghu Machiraju, Yair Kurzion et al. · OhioLink ETD Center (Ohio Library and Information Network) · 1999
In this paper, we present both a methodology and a rationale for designing filters based on spatial smoothness and accuracy criteria. Frequency based methods have been used to design function and derivative reconstruction filters especially in image and signal processing. Desired filter characteristics are specified in terms of spectral properties. However, for visualization and image synthesis algorithms it is more natural to specify a filter in terms of the smoothness of the resulting reconstructed function and the spatial reconstruction error. Most currently known filter choices are limited to specific set of functions, and the visualization practitioner has so far no way to state his preferences in a convenient fashion. We first state our design criteria. The filter performance in our framework is specified by listing the accuracy and smoothness (of reconstructed function) through the use of three criteria. We provide rigorous proof for the existence of a filter using results from ...
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Xuan Li, Haixian Wang · Lecture notes in computer science · 2013
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J. Pozgay · 1978
Abstract : This report summarizes the experimental investigation of a dielectric spatial filter. The spatial filter was designed under a previous effort. Specifically, the objectives were: To fabricate the spatial filter design under Contract F19628-76-C-0189; to test the completed filter with a linear array of polarization diverse circular elements. With respect to the test program the goal was to provide experimental confirmation of the filter concept and to investigate the array/filter interaction. The results of this study establish the effectiveness of such filters for reduction of sidelobes beyond 10 deg from broadside. (Author)
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C. M. Verber, Richard P. Kenan, J. R. Busch · Optics Communications · 1980
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Xiao Zhang · 2007
The key techniques of spatial filter matrix used in large laser facility such as super-long-distance beam transmission,beam control,beam quality control,stability of supporting structure,adjustment accuracy of all coupling glasses,stability of glass mounts,off-axis adjustment are studied.This paper surveys current technology of spatial filters,determines the specifications of the system,and finally provides a comprehensive solution for the structure design of spatial filter by using Pro/E software program in the 3-D simulation model of spatial filter matrix.The key components and specifications are analyzed carefully,and new structure design and techniques are employed.The rigidity,strength,and vibration modes of the structure are analyzed using ANSYS software program.The structure has been optimized by bidirectional embedding of finite element method and CAD.To seek the proof for the equipment structural flexibility,it has been tested with a slight shock to check the components and units, which has significant influence on the structure stability.
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Sebastian Braun, Oliver Thiergart, Emanuël A. P. Habets · 2014
When capturing speech in a multi-talker telecommunication scenario, it is desirable to keep the enhanced signal at an equal loudness level for each speaker. Single-channel automatic gain control systems are not able to adjust the level of different talkers when they are simultaneously active. In this work, an automatic spatial gain control (ASGC) algorithm is proposed that adjusts the directional response of an existing informed spatial filter such that the direct sound of multiple sources can be kept at a constant desired loudness level at the output. The spatial filter additionally reduces diffuse sound and ambient noise. It is shown that the proposed AGSC works well within the tested scenario, and is able to adjust the levels of different speakers even during double talk scenarios.
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Christina A. Burbeck, Yen Lee Yap · Vision Research · 1990
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J. Zorskie · American Journal of Physics · 1973
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Bruce Eaton, Joseph Zorskie; An Inexpensive Spatial Filter for Holography. American Journal of Physics 1 July 1973; 41 (7): 932. https://doi.org/10.1119/1.1987427 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAmerican Association of Physics TeachersAmerican Journal of Physics Search Advanced Search |Citation Search
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Xiaofang Zhou, Xuemin Lin, Chengfei Liu et al. · International Journal of Cooperative Information Systems · 2000
Spatial data, ranging from various land information data to different types of environmental data, are typically collected and used by different custodians. The full benefits of using spatial data can be achieved by combining the data from different sources covering a common region. Due to organizational, political and technical reasons, it is unrealistic to physically integrate the vast amount of spatial data managed by different systems in different organizations. A practical approach is to provide interoperability to support multi-site data queries. In this paper, we study the performance aspect of complex spatial query processing. We propose a framework for processing queries with multiple spatial and aspatial predicates using data from multiple sites. Using a new concept called generalized filter, a query is processed in three steps. First, an aspatial filter that incorporates some conditions derived from spatial predicates is used to find a set of candidates, which is a superset of the final query results. Then, the candidates are manipulated and a refinement step is executed following an optimized candidate sequence. Finally, a post-processing step is used to handle spatial expressions in query results. The focus of this paper is to generate enhanced filters in order to minimize the need of transferring and processing complex spatial data.
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Zhou, Xiaofang, Lin, Xuemin, Liu, Chengfei et al. · Figshare · 2000
Spatial data, ranging from various land information data to different types of environmental data, are typically collected and used by different custodians. The full benefits of using spatial data can be achieved by combining the data from different sources covering a common region. Due to organizational, political and technical reasons, it is unrealistic to physically integrate the vast amount of spatial data managed by different systems in different organizations. A practical approach is to provide interoperability to support multi-site data queries. In this paper, we study the performance aspect of complex spatial query processing. We propose a framework for processing queries with multiple spatial and aspatial predicates using data from multiple sites. Using a new concept called generalized filter, a query is processed in three steps. First, an aspatial filter that incorporates some conditions derived from spatial predicates is used to find a set of candidates, which is a superset of the final query results. Then, the candidates are manipulated and a refinement step is executed following an optimized candidate sequence. Finally, a post-processing step is used to handle spatial expressions in query results. The focus of this paper is to generate enhanced filters in order to minimize the need of transferring and processing complex spatial data.
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Konstantin B. Yushkov, Alexander I. Chizhikov, Dmitry V. Obydennov et al. · Optics Letters · 2024
An acousto-optic (AO) tunable filter with a phase-controlled dual-section piezoelectric transducer is designed and created for laser beam shaping (LBS). Owing to the acoustic beam steering effect, we experimentally observe splitting of the two-dimensional transfer function. As a result, we demonstrate generation of tunable bottle laser beams and dual-ring intensity distributions for the diffracted beam.
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H.J. Weaver · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1973
remainder of the report addresses the problem of designing stable 2-D recursive digital filters. A very efficient design procedure for separable 2-D recursive filters is presented. This procedure is useful in designing quarter-plane recursive filters, and is applicable to a limited subset of design problems. Finally, two techniques are presented for designing stable recursive filters of the more general half-plane variety. These techniques incorporate a recently developed 2-D spectral factorization procedure and a nonlinear optimization to obtain filters to approximate an arbitrary magnitude response, with a zero phase response if desired. Example designs are provided for each technique discussed. 29 figures, 4 tables, 64 references.
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P. W. Hannan, P. L. Burgmyer · 1980
Abstract : This interim report presents the results of studies relevant to the design of spatial filters that have metal grids as their basic reflecting element. An analysis of metal-grid spatial filter designs shows the performance that is available. An experimental investigation of various types of metal grids confirms their suitability for spatial filters. (Author)
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