Electrooptical Arrays

334 Pages·1989·12.09 MB·English

by  Dmitrii Ivanovich Voskresenskii

Electrooptical Arrays
D .1. Voskresenskii A. I. Grinev E.N. Voronin
Electrooptical Arrays
Translated by Peter F.H. Priest
With 123 Illustrations
Springer-Verlag New York Berlin Heidelberg
London Paris Tokyo
Dmitrii Ivanovich Voskresenskii
Aleksandr Iur'evich Grinev
Evgenii Nikolaevich Voronin
Moscow, USSR
Translator
Peter F.H. Priest
Rose-Hulman Institute of Technology
Terre Haute, IN 47803, USA
Original Russian edition Radioopticheskie antennye reshetiki published © 1986 by Radio i sviaz,
Moscow.
Library of Congress Cataloging-in-Publication Data
Voskresenskii, D.I. (Dmitrii I vanovich)
[Radioopticheskie antennye reshetki. English]
Electrooptical arrays / Dmitrii I. Voskresenskii, Alexander Y.
Grinev, Eugene N. Voronin ; translated by Peter F.H. Priest.
p. cm.
Translation of: Radioopticheskie antennye reshetki.
Bibliography: p.
Includes index.
ISBN-13: 978-1-4612-8120-7
1. Optical data processing. 2. Antenna arrays. I. Grinev, A.
IV. (Aleksandr IVr'evich) II. Voronin, E.N. (EvgeniI Nikolaevich)
III. Title.
TA1632.V6713 1989
621.38/0414 - dc19 88-39760
Printed on acid-free paper
© 1989 by Springer-Verlag New York Inc.
Softcover reprint of the hardcover I st edition 1989
All rights reserved. This work may not be translated or copied in whole or in part without the written
permission of the publisher (Springer-Verlag, 175 Fifth Avenue, New York, NY 10010, USA),
except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with
any form of information storage and retrieval, electronic adaptation, computer software, or by similar
or dissimilar methodology now known or hereafter developed is forbidden.
The use of general descriptive names, trade names, trademarks, etc. in this publication, even if the
former are not especially identified, is not to be taken as a sign that such names, as understood by
the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone.
Camera-ready copy provided in TEX by the translator.
987 6 5 4 3 2 I
ISBN-13: 978-1-4612-8120-7 e-ISBN-I3: 978-1-4612-3484-5
DOl: 10.1007/978-1-4612-3484-5
Preface
Modern radar, telecommunication, sonar, and radio-astronomy systems use
integrated systems, complex signals, and signal processing methods exten
sively. These systems require the development of new, more efficient systems.
One of the major ways to improve radar and sonar systems is to use
multichannel systems, the most promising of which employ space-time signal
processing.
In the last few years the intensive growth in electronics, informa
tion processing techniques, microwave and laser technology, electrooptics and
holography, acoustics, and optoelectronics have resulted in new scientific and
technological research fronts. One of these is the theory and technology of
electrooptical array antennas-a new class of receiving antennas whose pat
tern is controlled by means of coherent optics and holography. Electrooptical
array theory and technology have been involved in the study of the power,
resolution, and range characteristics of arrays with various coherent opti
cal processors. The practical applications of these systems and methods for
building them using contemporary optoelectronics have also been studied.
Optical information processing allows parallel processing in large two
dimensional data bases in real time. Therein lies their main advantage over
digital information processing. However, in terms of mathematical opera
tions, algorithms, and in the accuracy of their computations, optical infor
mation processing is inferior not only to digital computers but also to analog
computing techniques. This lack of versatility of optical processors can be
overcome in two ways. One is by developing a hybrid optoelectronic com
puting system that uses a general purpose computer and a special optical
computer that combines the rapid response time and the productivity of op
tical information processing methods with the flexibility and the precision
of computers. The second method is to use problem-oriented analog optical
processors for solving highly specialized tasks. Let us note that currently
there is much promise in a third method, using an optical computer that
processes digital information using an optoelectronic device.
When considering the suitability of using optical devices for processing
radar and sonar signals, it is useful to distinguish two groups of tasks:
1. Those problems that are difficult to solve using traditional electronic
methods (the clearest example is panoramic scanning over a broad
range of frequencies and look-angles);
2. Those problems that can be solved by traditional electronic means as
well as by optical ones. In this case, the major considerations are
simplicity, compactness, cost, and so forth.
The general issues in optical information processing and holography are
treated in monographs by Born and Wolf [1], Papoulis [2], Goodman [3],
Kondratenkov [4], Soroko [5], Collier, Burckhardt, Lin [6], and also in ar
ticles in various references [7-38]. Articles by Russian and foreign authors
devoted to optical signal processing techniques, for example in [39-46], treat
only certain problems in processing space-time signals received by array an
tennas (the shaping of the array pattern in real time). The exception is
synthetic aperture antennas that are examined in detail in, for example,
works by Reutov, Kondratenkov and their colleagues [47,48].
The potential advantages of an optical space-time signal processing
device in radar and sonar applications are now drawing increased atten
tion. However, a situation has developed where the existing proposals for
equipping arrays with coherent optical signal processors are ahead of the
current state of the art. At the same time we do not have any systematic
and complete exposition of the coherent optical methods for producing the
directional characteristics because these descriptions have been scattered in
separate monographs, articles, conference proceedings, and patents. A num
ber of important issues have reached the critical stage: in particular, how to
maximize the scanning sector, how to combat interfering spatial signals, how
to improve resolution, etc. These problems hamper the design of such sys
tems. Therefore, one inevitably either overestimates the potential of optical
methods in array signal processing or limits their use when the applications
of digital and nonoptical analog methods are being rapidly developed, a
situation which is not always justified by technological or economic consid
erations.
This book, based on the original work of the authors and on a review
of Soviet and foreign publications, treats three aspects of electrooptical array
antennas. First, it presents from a single point of view, a theory of electroop
tical array antennas as a system which performs coherent optical processing
of spatial signals and studies their properties and performance. Second, it
proposes and describes some new coherent optical methods which signifi
cantly expand the practical applications of electrooptical arrays. Third, it
treats various designs and discusses basic electrooptical array components
and presents experimental data which illustrate the applications of arrays
vi
which produce their patterns by means of coherent optic and holographic
techniques.
Finally, using a single electrooptical approach we will examine elec
trooptical arrays that produce either two-dimensional spatial directional
characteristics or panoramic scanning along angular coordinates parallel with
a spectral and correlation analysis. We will study nonplanar electrooptical
arrays which make it possible to perform two-dimensional broad-band scan
ning. We will examine interference-resistant electrooptical arrays that use
spectral techniques for rejecting interfering signals. In order to evaluate the
potential for electrooptical arrays, we must study the influence of optical
processor errors on the accuracy of the antenna pattern, on the dynamic
range, and on the maximum gain. We will determine the electrooptical ar
ray sensitivity to thermal and quantum noise. Inasmuch as at certain stages
"even a little knowledge is worth a great deal," we will, therefore, conclude
with a description of a number of different coherent optical processors for
electrooptical arrays that use existing and emerging technologies and which
have different practical applications. We will also describe the results of ex
perimental research and discuss some of the trends in electrooptical array
development.
The range of applications for the material in this book is broad enough
if we take into account the multiple applications of electrooptical arrays, for
instance, in sonar technology, though specific features of such systems are
beyond the scope of this work.
vii
Contents
Preface v
Basic Mathematical Terms and Abbreviations xv
1 Array Antennas with Coherent Optical Signal Processing 1
1.1 The Potential for Parallel Processing of Space-Time Signals
with Coherent
Optical Techniques . . . . . . . . . . . . . . . . . . . . . . .. 1
1.2 Electrooptical Array Antennas.
Background and State of the Art . . . . . . 5
1.2.1 Structure of the electrooptical array 5
1.2.2 Types of electrooptical arrays . 10
1.3 The Components of an Electrooptical
Array Antenna . . . . . . . . . . . . . . . . . . . . . . . . .. 18
1.3.1 General information . . . . . . . . . . . . . . . . . .. 18
1.3.2 Space-time light modulators in an electrooptical array 18
1.3.3 Output devices ..................... , 20
2 Formation of Planar Array Antenna Patterns 24
2.1 Pattern Control Characteristics of
Electrooptical Planar Arrays .................. 25
2.2 Accuracy, Power and Range Properties of Electrooptical Arrays 30
2.2.1 Accuracy .... 30
2.2.2 Power............. ..... . 33
2.2.3 Range properties . . . . . . . ..... . 35
2.2.4 Transformation of the information block 38
3 Array Antennas with Space-Time Signal Processing 41
3.1 Pattern and Spectrum Shaping
Characteristics of Linear Electrooptical Arrays Using Multi
channel
Acoustooptical Space-Time Light
Modulation . . . . . . . . . . ... 42
3.1.1 Coherent optical regeneration of the frequency angular
spectrum ................ . 42
3.1.2 Precision and power characteristics . . . . 45
3.1.3 Comparison of Raman-Nath and Bragg
diffraction in coherent optical processors . 48
3.1.4 Transformation of the information block 50
3.2 Linear Electrooptical Array with
Electron Beam and Optical Signal
Addressing Input Devices . . . . . . . . . . . . . . . . 51
3.2.1 Pattern- and spectrum-forming properties . . . 51
3.2.2 Requirements for space-time light modulators. 53
3.3 Coherent Optical Processors for Planar Array Antennas with
Space-Time Light Modulator with a Complex Law for
Addressing the Input Signal . . . . . . 57
3.3.1 Complex input format . . . . . 57
3.3.2 Two-dimensional input format 64
3.4 Linear Arrays with Correlation Signal
Processing . . . . . . . . . . . . . . . . 67
4 Formation of the Antenna Pattern of Nonplanar Array An-
tennas 71
4.1 The Restoration Algorithm . . . . . . . . . . . . 72
4.1.1 The coherent optical processing algorithm 72
4.1.2 Characteristics of the algorithm. . . . . . 74
4.2 Implementing the Processing Algorithm with Coherent Optics 78
4.2.1 Piecewise planar arrays ... . . . . . . . . . . . . .. 79
4.2.2 Array antennas on the surface of a circular
cylinder . . . . . . . . . . . 82
4.2.3 Circular arrays . . . . . . . 87
4.3 Random Axially-Symmetric Array
Antennas ............................ 93
4.3.1 Description of the algorithm. . . . . . . . . . . . .. 93
4.3.2 Coherent optical processor employing a volume filter 95
4.3.3 Implementing the processor . . . . . . . . . 98
4.3.4 The axially symmetric electrooptical array. 99
4.4 Phase Correction Method . . . . . . . . . . . . . . 101
5 Discreteness Effects in Planar and Nonplanar Electrooptical
Antenna Arrays 103
5.1 Arbitrary NonpJanar ElectroopticaJ
Antenna Array . . . . . . . . . . . . . . . . . . . . . . . 103
5.1.1 Redundancy of the starting processing algorithm 106
x
5.1.2 Effect of finite channel widths on the space-time light
modulator. . . . . . . . . . . . . . . . . . . . . 106
5.1.3 Interference between channels in the modulator 108
5.2 Effects of Discreteness of Planar
Electrooptical Antenna Arrays ....... . 109
5.2.1 Simplification of the Fourier processor 109
5.2.2 Pupil effect of modulator channels .. 114
5.2.3 Effect of interference between modulator
channels .................. . 118
5.2.4 Methods of eliminating ambiguity in the
determination of coordinates .............. 120
5.3 Effects of discreteness of cylindrical
electrooptical arrays . . . . . . . . . . . . . . . . . . . . . . . 123
5.3.1 Reduction of the coherent optical processor of cylin-
drical arrays ................ 123
5.3.2 Pupil effect of modulator channels . . . . 129
5.3.3 Effect of interference between modulator
channels .................. . 131
6 Rejection of Interference by Coherent Optical Methods 136
6.1 Statement of Problem. Choice of
Criterion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
6.2 Interference Suppression Processing
Algorithm and Options for Its
Implementation. . . . . . . . . . . . 141
6.2.1 Processing algorithm. . . . . 142
6.2.2 Options for realizing the processor 145
6.2.3 Structure of the mask . . . . 147
6.3 Processor with Ideal Suppression of
Spatial Noise Signals . . . . . . . . . . . . . . 149
6.3.1 Evaluation of the depth of suppression 150
6.3.2 Generation of ideal nulls . . . . . . . . 151
6.3.3 Comments................ 156
6.4 Examples of Electrooptical Arrays with Noise Rejection 157
6.4.1 Planar electrooptical antenna array with
arbitrary aperture shape. . . . . . . . . . . . . . 157
6.4.2 Linear and planar electrooptical antenna arrays with
rectangular apertures .................. 160
6.4.3 Planar electrooptical array with circular
aperture . . . . . . . . . . . . . . . . . . . . . . . . . . 166
6.5 Generalization of the Coherent Optical Method of Noise Re
jection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
xi
6.5.1 Suppression of sectorial noise . . . . . . . . . . . . . . 170
6.5.2 Linear electrooptical arrays with space-time light mod
ulators using spatial scanning of a time
signal . . . . . . . . . . . . . . . . . . . . 171
6.5.3 Cylindrical electrooptical array . . . . . . 174
6.5.4 Effect of discreteness of the array and the
space-time light modulator . . . . . . . . . . . . . . . 176
6.6 Effect of Errors in the Realization of the Spatial Filter on the
Depth of Null
Formation . . . . . . . . . . . . . . . . . . . . . . . . . . .. 177
7 The Influence of Uncertainties on Electrooptical Arrays 182
7.1 The Electrooptical Array Antenna Gain . . . . . . 183
7.2 Coherent Optical Processor Errors . . . . . . . . . 185
7.2.1 The effect of the pupil and space-time light
modulator channel interaction. . . . . . . . . . . . . . 186
7.2.2 Potential accuracy and the coherent optical
processor optical system aberrations . . . 187
7.2.3 Coherent processor element misalignment 189
7.2.4 Spatial incoherence of the reading light . 191
7.2.5 Time incoherence of the light source . . . 194
7.2.6 Fresnel light reflection from coherent optical
processor elements . . . . . . . . . . . . 198
7.2.7 Limiting the dynamic range. . . . . . . 200
7.3 Space-time Light Modulator Distortion Factors 201
7.3.1 Dual-band input . . . . . . . . . . . . . 201
7.3.2 Space-time light modulator modulation
characteristic nonlinearity . . . . . . . . . . . . . . . . 203
7.3.3 Zero order diffraction .................. 209
7.3.4 The presence of distortion in coherent optical proces-
sors with AOM-based input devices .......... 210
7.3.5 Non-linear distortions in coherent optical
processors with input devices based on
space-time light modulators with electronic and
optical addressing [107]. 213
7.3.6 Comments...................... 214
8 Electrooptical Array Sensitivity 217
8.1 Thermal Noise in Electrooptical Arrays 218
8.1.1 External thermal noise ..... . 218
8.1.2 Internal thermal noise in electrooptical arrays. 219
8.2 Quantum Noise in Electrooptical Array with Incoherent Pho-
todetection ............................ 221
xii