Theory and Technology of Laser Imaging Based Target Detection (eBook)

Preface 5
Contents 8
1 Introduction 13
1.1 Concept of Laser Imaging 13
1.1.1 Origin of Laser Imaging 13
1.1.2 Characteristics of Laser Imaging 15
1.1.3 Types of Laser Imaging 17
1.2 Concept of Target Detection Based on a Laser Imaging System 19
1.2.1 Laser Detection and Laser Imaging 19
1.2.2 Definition of the Target Detection Technology Based on Laser Imaging 20
1.2.3 Characteristics of Target Detection Based on a Laser Imaging System 21
1.3 Principle of the Target Detection Based on a Laser Imaging System 23
1.3.1 Range Equation of Laser Detection 24
1.3.2 Target Sampling of Laser Imaging 27
1.3.3 Information Acquisition and Processing of Target Detection Based on a Laser Imaging System 31
References 34
2 The Atmospheric and Target Modulations of the Lasers 36
2.1 The Concepts of the Atmospheric and Target Modulations of Lasers 36
2.2 The Atmospheric Modulation of the Lasers 39
2.2.1 The Absorption Characteristics of the Atmosphere for the Lasers 39
2.2.2 The Characteristics of Atmospheric Scattering for the Lasers 42
2.2.3 The Atmospheric Turbulence of Lasers 47
2.3 Target Modulation of Lasers 53
2.3.1 The Characteristics and Analytical Method of the Target Modulation of Lasers 53
2.3.2 The Modulation Characteristics of the Laser Echoes Energy 55
2.3.3 The Modulation Characteristics of the Waveform of the Laser Echoes 64
2.4 Typical Target and Atmospheric Modulations 67
2.4.1 Typical Target Modulation 67
2.4.2 Typical Atmospheric Modulation 72
References 74
3 The Target Detection System Based on Laser Imaging 75
3.1 Components of the System 75
3.1.1 Laser Transmitting System 76
3.1.2 Optical Receiving and Detection System 77
3.1.3 System for Delay Measurement and Echo Acquisition 77
3.1.4 Positioning and Orientation System 78
3.1.5 Data Processing and Image Generation System 79
3.1.6 Target Detection and Location System 79
3.1.7 Target Classification and Identification System 79
3.1.8 Units for Controlling, Monitoring and Recording 80
3.1.9 Photoelectric Transceiving and Calibration System 80
3.2 Laser Transmitting System 80
3.2.1 Lasers and Laser Trigger Circuits 81
3.2.2 Laser Collimators and Optical Transmitting Systems 83
3.3 Optical Receiving and Detection System 85
3.3.1 Optical Receiving Systems 86
3.3.2 Main Technical Parameters 89
3.3.2.1 Receiving View Angle 90
3.3.2.2 Types of Detectors 91
3.3.2.3 SNR 91
3.3.3 Background Light Suppression 93
3.4 Photoelectric Transceiving and Calibration System 97
3.4.1 Calibration for Array Transmitting and Receiving Light Path 97
3.4.1.1 Optical Path Calibration 98
3.4.1.2 Registration Test of the Transmitting and Receiving Axes 99
3.4.2 Calibration for Ranging Precision 99
3.4.2.1 Echo Intensity Detection for Laser Echo Pulses 100
3.4.2.2 Ranging Error Correction Method Based on Echo Intensity 101
3.4.3 Calibration of Channel Consistency 104
3.5 POS System 108
3.5.1 Dynamic Differential GPS Positioning System 108
3.5.2 INS-Based Orientation Determination System 110
3.6 Typical Target Detection Systems Based on Laser Imaging 111
3.6.1 Compositions and Functions of the System 111
3.6.2 Main Performance Parameters 113
References 113
4 Acquisition of Detection Information 115
4.1 The Target Sampling and Beam Scanning 115
4.1.1 Characteristics of Laser Spot in Emission Sampling 116
4.1.2 The Detection Results Based on Dynamic Beam Scanning 117
4.1.3 Adaptively Variable-Speed Scanning for Target Sampling with Variable Resolutions 121
4.2 The Information Acquisition for the Target Detection Based on a Laser Imaging System 127
4.2.1 The Formation of Transmitting Laser Beam in Array Detections 128
4.2.2 Array Reception and Detection of Laser Echo 135
4.2.3 Amplifying and Processing Laser Echo Signals 141
4.2.4 Waveform Digitization of Laser Echoes 147
4.3 Data Collection for the Detection Based on a Laser Imaging System 150
4.3.1 Discrimination of the Arrival Time of Echo Pulses 151
4.3.2 The High-Resolution Measurement of Time Delay of Multi-channel Echoes 156
4.3.3 The High-Resolution Measurement of the Gray of Multi-Channel Echoes 166
References 168
5 Detection Data Processing and Image Generation 170
5.1 Processing of Detection Data 170
5.1.1 File Processing 171
5.1.2 Data Processing 173
5.2 Generation of Range Images and Gray Images of Targets 179
5.2.1 Methods for Generating Images 179
5.2.2 Process of Image Generation 181
5.3 Generation of Waveform Images of Targets 185
5.3.1 Expression of the Waveform of Laser Echoes 185
5.3.2 The Data Extraction of Target Waveforms Based on LSM 187
5.3.3 Extraction of Waveform Data Based on EM Algorithm 190
5.4 Generation of Hierarchy Images of Targets 192
5.4.1 Principle of Level Imaging of Targets 193
5.4.2 Processing Multiple Echoes 194
5.4.3 Generation of Hierarchy Images of Targets 199
References 199
6 Feature Extraction and Processing of Detection Images 200
6.1 Feature Analysis of Laser Images 200
6.1.1 Width Features of Target Echoes 200
6.1.2 Energy Features of Echoes 201
6.1.3 Distribution Characteristics of Waveforms 202
6.1.4 Statistical Characteristics of Waveform Images 206
6.2 Feature Extraction of Laser Images 208
6.2.1 Extraction of Energy Characteristics Based on Multi-scale Wavelet Transform 209
6.2.2 The Extraction of Waveform Characteristics Through Wavelet Transform Based on WTMMs 219
6.3 Evaluating the Separability of Characteristics 225
6.3.1 The Measurement of Class Separability 225
6.3.2 Evaluation of Wavelet Characteristics 226
References 228
7 The Extraction of the Features of Targets Detected Using a Laser Imaging System 230
7.1 The Principle of the Extraction of Target Features 230
7.1.1 Extracting Structure Features of Targets Based on the Time Delay and Level of Echoes 231
7.1.2 Extracting Features of Physical Properties of Targets Based on the Echo Energy 233
7.1.3 The Extraction of Comprehensive Features of Targets Based on Echo Waveforms 235
7.2 The Feature Extraction of Ground Targets Based on Echo Waveforms 236
7.2.1 The Model of Laser Echoes Reflected from Ground Targets 238
7.2.2 Parameter Analysis of Ground Targets 240
7.3 Feature Extraction of Aerial Targets Based on Echo Waveforms 242
7.3.1 Expression of Laser Echoes of Aerial Targets 243
7.3.2 The Model of Extracting the Range Features of Aerial Targets 244
7.3.3 The Model of Extracting the Displacement Features of Aerial Targets 249
7.3.4 The Model of Extracting the Attitude Features of Aerial Targets 253
7.4 The Extraction of Target Features Based on the Reference Echo Pulses 260
7.4.1 Constructing Principle of the Reference Echo Pulse 261
7.4.2 Steps for Constructing the Reference Echo Pulses 262
7.4.3 Features of Reference Echo Pulses 263
References 265
8 Target Detection and Location Using a Laser Imaging System 266
8.1 Target Detection Based on Range Images 266
8.1.1 Analyzing Characteristics of Range Images 266
8.1.2 Range Separation and Layering of Images 268
8.1.3 Target Fitting and Detection 271
8.2 Covered Targets Detection Based on Waveform Images 273
8.2.1 Principles of Target Detection 274
8.2.2 Laser Echo Model for Hidden Targets 275
8.2.3 The Detecting Algorithm for Hidden Targets 277
8.2.4 Analyzing the Features of Hidden Targets 281
8.2.4.1 The Determination of Imaging Range of Hidden Targets 281
8.2.4.2 Evaluation of the Features of Hidden Targets 284
8.2.5 Experiments and Analysis 287
8.3 Target Location Based on a Laser Imaging System 298
8.3.1 The Principle of Target Location 298
8.3.2 The Positioning Error 300
8.3.2.1 Radial Error 300
8.3.2.2 Comprehensive Error 302
References 303
9 The Target Classification and Identification for the Target Detection Based on a Laser Imaging System 305
9.1 Feature Transformation of Detection Images 305
9.2 Target Classification and Identification Based on the Radial Basis Function Neural Network 308
9.2.1 The RBFNN-Based Sorting Algorithm 308
9.2.2 Classification and Identification Methods 309
9.2.3 Experiments and Analysis 311
9.3 Target Classification and Identification Based on the Support Vector Machine 316
9.3.1 The Principle of the Classification Based on the SVM 316
9.3.2 The Design of Classifiers 319
9.3.3 Experiments and Analysis 321
References 326
10 Analysis of the Errors of the Target Detection Based on a Laser Imaging System 327
10.1 Classification of Error Sources 327
10.2 Data Acquisition Errors 329
10.3 System Errors 336
10.4 System Integration Errors 339