Contents
Preface Foreword
CHAPTER 1
Theoretical Basis of Laser Coherent Detection 1
1.1 Overview of Laser Detection 1
1.2 Principles of Laser Coherent Detection 2
1.2.1 Square-Law Characteristic of Photoelectric Detectors 3
1.2.2 Characterization of Laser Coherent Detection Signals 3
1.3 Signal-to-Noise Ratio of Laser Coherent Detection 5
1.3.1 Noise of Photoelectric Detectors 5
1.3.2 Signal-to-Noise Ratio of Coherent Detection 7
1.4 Coherence Efficiency of Laser Coherent Detection 9
1.4.1 Signal and LO Optical Fields 9
1.4.2 Coherence Efficiency Analysis 11
1.5 Basic Characteristics of Laser Coherent Detection 11
1.6 Overview of Typical Applications of Laser Coherent Detection 13
1.6.1 Laser Detection of Atmospheric Disturbances 13
1.6.2 Laser Ranging and Velocity Measurement 17
1.6.3 Laser Detection Based on the Micro-Doppler Effect 20
1.6.4 High-Resolution Synthetic Aperture Laser Imaging 23
References 27
CHAPTER 2
Laser Coherent Detection of Atmospheric Disturbances 29
2.1 Fundamental Principles 29
2.1.1 Radar Equation for Laser Detection of Atmosphere 29
2.1.2 Fundamental Principles of Laser Coherent Atmospheric BCO2 Detection 32
2.1.3 Fundamental Principles of Laser Coherent Detection of Wind-Field Disturbances 39
2.2 Experimental System for Laser Coherent Detection of Atmospheric Disturbances 42
2.2.1 Overall Structure of the Detection System 42
2.2.2 Parameter Design of the Detection System 46
2.2.3 Pulse Data Processing of Detection Echoes 57
2.3 Laser Coherent Detection Experiments of Atmospheric Disturbances 62
2.3.1 Atmospheric CO2 Detection Experiments 62
2.3.2 Atmospheric Wind-Field Detection Experiments 68
References 74
CHAPTER 3
Chirped AM Laser Coherent Detection of Range and Velocity 77
3.1 Fundamental Principles 77
3.1.1 Principle of Chirped AM Ranging 79
3.1.2 Principle of Chirped AM Velocity Measurement 79
3.2 Characteristics of Chirp Signals and De-Chirping 80
3.2.1 Chirp Signals and Their Ambiguity Function 80
3.2.2 Pulse Compression by a Matched Filter 83
3.2.3 Frequency-Domain Pulse Compression of Chirp Signals 84
3.2.4 Range-Velocity Coupling 86
3.3 Balanced Coherent Detection 87
3.4 Chirped AM Laser Coherent Detection Experiment of Range and Velocity 88
3.4.1 Chirped AM Laser Heterodyne Coherent Detection Experiments of Range 89
3.4.2 Chirped AM Laser Homodyne Coherent Detection Experiments of Range and Velocity 95
References 102
CHAPTER 4
Laser Coherent Detection Based on the Micro-Doppler Effect 103
4.1 Fundamental Principles of the Micro-Doppler Effect for Laser Detection 103
4.1.1 Doppler and Micro-Doppler Effects 103
4.1.2 Modeling of Echoed Photocurrent Signals in Target Vibration Detection 105
4.1.3 Modeling of Echoed Photocurrent Signals of Targets with Multiple Scattering Points 108
4.1.4 Influencing Factors of Characteristics of Laser Micro-Doppler Signals 112
4.2 Target Micro-Doppler Signal Acquisition and Experimental System for Laser Coherent Detection 119
4.3 Target Micro-Motion Feature Extraction Based on TFA 121
4.3.1 TFA of Micro-Doppler Signals of Targets 121
4.3.2 Decomposition of Time-Frequency Features
of Multi-Component Signals Based on Curve Tracking 125
4.3.3 Separation and Extraction of Time-Frequency Features
of Micro-Motions Based on Empirical Mode Decomposition 128
4.4 Micro-Motion Parameter Estimation Based on Signal Models 132
4.4.1 Micro-Motion Parameter Estimation Using PF Based on SPM 132
4.4.2 Micro-Motion Parameter Estimation Based on ML 136
References 152
CHAPTER 5
Laser Coherent Detection Using Synthetic Aperture Technology 155
5.1 Fundamental Principles of SALs 155
5.1.1 Intuitive Concept of Synthetic Aperture in Lidars 155
5.1.2 Echo Signal Model of SALs 157
5.1.3 Fundamental Principles of Coherent Mixing of Chirp Signals 160
5.2 SAL Imaging Algorithms 162
5.2.1 R-D Imaging Algorithm 162
5.2.2 Phase Gradient Autofocus Algorithm 170
5.3 Laser Coherent Detection Experiments Using Synthetic Aperture Technology 173
5.3.1 Structure of the Experimental System 173
5.3.2 Data Processing Flow 177
5.3.3 Analysis of Experimental Results 178
References 194