Produits agricoles : projections pour 1970 : rapport de la FAO sur les produits, 1962 : Supplément spécial / FAO

• Record Nr.: UNINA990006937270403321
• Autore: FAO
• Pubbl/distr/stampa: Rome : FAO, 1962
• Descrizione fisica: paginazione varia ; 24 cm
• Disciplina: 341
• Locazione: FGBC
• Collocazione: XXII FAO 9
• Lingua di pubblicazione: Francese
• Formato: Materiale a stampa
• Livello bibliografico: Monografia

Adaptive optics theory and its application in optical wireless communication / / Xizheng Ke and Pengfei Wu

• Record Nr.: UNINA9910743341603321
• Autore: Ke Xizheng
• Pubbl/distr/stampa: Beijing ; ; Singapore : , : Science Press : , : Springer, , [2022]; ©2022
• ISBN: 981-16-7901-0; 981-16-7900-2
• Descrizione fisica: 1 online resource (387 pages)
• Collana: Optical wireless communication theory and technology
• Disciplina: 621.3827
• Soggetti: Optical communications; Optics, Adaptive; Wireless communication systems
• Lingua di pubblicazione: Inglese
• Formato: Materiale a stampa
• Livello bibliografico: Monografia
• Nota di contenuto: Intro -- Preface -- Introduction -- Contents -- 1 Introduction -- 1.1 Wireless Optical Coherent Communication Research Status -- 1.1.1 Research Status in the United States -- 1.1.2 Research Status in Europe -- 1.1.3 Research Status of Japan -- 1.1.4 Research Status of China -- 1.2 Adaptive Optics -- 1.2.1 International Research Progress in Adaptive Optics -- 1.2.2 Chinese Research Progress in Adaptive Optics -- 1.2.3 Adaptive Optics Development Trends -- References -- 2 Coherent Optical Communication -- 2.1 Basic Principles of Coherent Optical Communication -- 2.1.1 Fundamentals -- 2.1.2 Homodyne Detection -- 2.1.3 Heterodyne Detection -- 2.1.4 Detection of an Amplitude Modulated Signal -- 2.1.5 Dual-Channel Balanced Detection -- 2.2 Coherent Modulation and Demodulation -- 2.2.1 Optical Modulation -- 2.2.2 Coherent Demodulation -- 2.2.3 System Performance -- 2.3 Factors Affecting Detection Sensitivity -- 2.3.1 Phase Noise -- 2.3.2 Intensity Noise -- 2.3.3 Polarization Noise -- 2.3.4 Key Technologies of Coherent Optical Communication Systems -- 2.4 Spatial Phase Conditions for Optical Heterodyne Detection -- 2.4.1 Spatial Phase Difference Conditions -- 2.4.2 Frequency Conditions -- 2.4.3 Polarization Conditions -- 2.5 Summary and Outlook -- References -- 3 Adaptive Control of Wavefront Distortion -- 3.1 The Basic Principle of Coherent Optical Communication -- 3.2 Adaptive Optics Technology -- 3.2.1 Basic Principles -- 3.2.2 Wavefront Sensor -- 3.2.3 Wavefront Corrector -- 3.2.4 Wavefront Distortion Correction Principle -- 3.2.5 Beam Quality Evaluation Index -- 3.3 Wavefront Correction Algorithm of a Double Deformable Mirror -- 3.3.1 Wavefront Distortion Caused by Atmospheric Turbulence -- 3.3.2 Numerical Analysis of Wavefront Distortion -- 3.3.3 Experiment on Adaptive Control of Wavefront Distortion of Pendulum Mirror and Deformable Mirror.; 3.4 Wavefront Distortion Predictive Control -- 3.4.1 Adaptive Optics Model -- 3.4.2 Subspace System Identification -- 3.4.3 Predictive Control Experiment of Wavefront Distortion -- 3.5 System Error Analysis and Suppression -- 3.5.1 Error Analysis of Adaptive Optics System -- 3.5.2 Method of Restraining System Error -- 3.5.3 Comparison of Error Suppression Methods -- 3.6 Adaptive Control of Wavefront Distortion -- 3.6.1 PI Control Algorithm -- 3.6.2 Closed-Loop Control Parameter Adjustment -- 3.7 System Calibration -- 3.7.1 System Composition -- 3.7.2 Push-Pull Calibration -- 3.7.3 Hadamard Matrix Calibration -- 3.8 Closed-Loop -- 3.8.1 Closed-Loop Algorithm -- 3.8.2 Closed-Loop Bandwidth -- References -- 4 Adaptive Optics Calibration Methods -- 4.1 Proportional Integral Algorithm -- 4.1.1 System Response Matrix Calibration -- 4.1.2 Control Principles of PI Algorithm based on Direct Slope Method -- 4.1.3 Control Principles of Iterative Algorithm -- 4.2 Influence of Parameters on PI and Iterative Algorithms -- 4.2.1 PI Control Algorithm Parameters -- 4.2.2 G-S Algorithm Parameters -- 4.2.3 ILC Algorithm Parameters -- 4.2.4 Comparing the PI and Iterative Algorithms -- 4.2.5 Algorithm Operation Volume Analysis -- 4.3 Coherent Optical Communication Wave Front Correction Experiment -- 4.3.1 Analysis of the Closed-Loop Control Effect of the Wave Front Controller -- 4.3.2 Influence of AO Closed Loop Correction on Wave Front PV and Wave Front Root Mean Square -- 4.3.3 Influence of AO Closed-Loop Correction on Coupling Effect and Intermediate Frequency Signal -- References -- 5 Dual Fuzzy Adaptive Proportional Integral Derivative (PID) Control -- 5.1 Dual Fuzzy Adaptive PID Control Principle Based on the Direct Slope Method -- 5.2 Influence of the Input and Output Domains on the Fuzzy Adaptive PID Algorithm -- 5.2.1 Control Voltage.; 5.2.2 First Derivative of the Control Voltage -- 5.2.3 Output Domain -- ; 5.3 Fuzzy Control Experiment -- 5.3.1 Experimental Setup of the AO System -- 5.3.2 Iterative Control Algorithm Calibration Experiment -- 5.3.3 PID Control Algorithm Calibration Experiment -- References -- 6 Wave Front Correction Using the Stochastic Parallel Gradient Descent (SPGD) Algorithm -- 6.1 Wave Front Correction of Distorted Gaussian Beams Using the SPGD Algorithm -- 6.1.1 SPGD Algorithm -- 6.1.2 Optical Transmission Equation and Multiphase Screen Method -- 6.1.3 Simulation of Gaussian Beam Propagation in Atmospheric Turbulence -- 6.1.4 Wave Front Correction under Different Turbulence Intensities -- 6.1.5 Performance Improvement of Coherent Optical Communication System Using AO -- 6.2 Wave Front Distortion Correction Experiment Using the SPGD Algorithm -- 6.2.1 Correction of Static Wave Front Distortion -- 6.2.2 Wave Front Correction of a Heterodyne Detection Coherent Optical Communication System Using the SPGD Algorithm -- References -- 7 Wave Front Distortion Correction Using Deformable Mirror Eigenmode Method -- 7.1 Deformable Mirror Method -- 7.1.1 System Functions -- 7.1.2 Correction Factor -- 7.1.3 Deformable Mirror Intrinsic Mode -- 7.2 Simulating Wave Front Correction Using the Eigenmode Method -- 7.2.1 Calibration Process and Method -- 7.2.2 Deformable Mirror Modeling and Its Eigenmode -- 7.3 Wave Front Correction Simulation Using the Deformable Mirror Eigenmode Method -- 7.3.1 Influence of Turbulence Intensity -- 7.3.2 Fast Stable Convergence -- 7.3.3 Comparison of Different Correction Algorithms -- 7.4 Deformable Mirror Eigenmode Method -- 7.4.1 The Deformable Mirror Influence Function and Its Eigenmode -- 7.4.2 Static Aberration Correction Experiment -- 7.4.3 Field Experiment -- References.; 8 Vortex Beam Wave Front Correction Without Using a Wave Front Detector -- 8.1 Vortex Beam Propagation Characteristics Through Atmospheric Turbulence -- 8.1.1 Laguerre-Gaussian (LG) Beam -- 8.1.2 Vortex Beam Transmission Through Atmospheric Turbulence -- 8.1.3 Orbital Angular Momentum (OAM) of the Vortex Beam -- 8.2 Wave Front Correction Using the Phase Difference Method -- 8.2.1 Principles of Wave Front Correction Using the Phase Difference Method -- 8.2.2 Numerical Simulation of Vortex Beam Correction Using the Phase Difference Method -- 8.2.3 Convergence Analysis of the Phase Distribution Algorithm -- 8.3 Vortex Beam Correction Using the Gerchberg-Saxton (GS) Algorithm -- 8.3.1 Correction Principle -- 8.3.2 Simulation Results -- 8.4 Stochastic Parallel Gradient Descent (SPGD) Algorithm -- 8.5 Wave Front Distortion Correction Experiment Using the GS and SPGD Algorithms -- 8.5.1 GS Algorithm -- 8.5.2 SPGD Algorithm -- References -- 9 Liquid Crystal Adaptive Optics -- 9.1 Principles of Liquid Crystal Phase Modulation -- 9.1.1 Structure of a liquid crystal spatial light modulator (LC-SLM) -- 9.1.2 Principles of am LC-SLM -- 9.1.3 Wave Front Distortion Control Method -- 9.2 Phase Calibration Principles of LC-SLM -- 9.2.1 Interference Fringe Movement Method -- 9.2.2 Experimental Principle of the Interference Fringe Movement Method -- 9.3 Phase Calibration Experiment -- 9.3.1 Reflective LC-SLM Phase Calibration Experiment -- 9.3.2 Least Squares Fitting -- 9.4 Reflective LC-SLM Spatial Coherent Optical Communication Wave Front Correction System -- 9.4.1 Wave Front Correction Principle Using a Reflective LC-SLM -- 9.4.2 Basic Composition of the Wave Front Correction System -- 9.5 Principles of Wave Front Measurement -- 9.5.1 Static Wave Front Measurement Using the Transverse Shear Interferometer.; 9.5.2 Shack-Hartmann Real-Time Wave Front Measurement Principle -- 9.6 Wave Front Reconstruction -- 9.6.1 Zernike Polynomial -- 9.6.2 Wave Front Reconstruction Using the Zernike Polynomial -- 9.7 Reflective LC-SLM Wave Front Correction Experiment -- 9.7.1 Static ; Wave Front Correction -- 9.7.2 Field Experiment -- References -- 10 Wave Front Variations of Gaussian Beams with Different Wavelengths Propagating in Atmospheric Turbulence -- 10.1 Beam Propagation in Turbulence -- 10.1.1 Wave Front Fluctuation Variance Corresponding to Different Wavelengths -- 10.1.2 Wave Front Fluctuation of Different Wavelength Beams -- 10.2 Dual Wavelength Adaptive Optics -- 10.2.1 Adaptive Optics (AO) -- 10.2.2 Influence of the Wave Front Sensor on Detection Performance -- 10.3 Influence of the Wave Front Corrector -- 10.3.1 Impact of System Bandwidth -- 10.3.2 Wave Front Correction Coefficient Corresponding to Wavelength -- 10.4 Numerical Simulation and Analysis -- 10.4.1 Numerical Simulation of Global Wave Front Variance -- 10.4.2 Wave Front Correlation -- 10.4.3 Wave Front Spatial Differences on the Receiving Aperture -- 10.4.4 Correction Status with Correction Factor -- 10.4.5 Wave Front Distortion Experiment Corresponding to Different Wavelengths -- References -- 11 Adaptive Control of Large Amplitude Wave Front Distortion and Tilt -- 11.1 Residual Correction of Large Amplitude Wave Front Distortion -- 11.1.1 Theoretical Analysis of Large Amplitude Wave Front Distortion -- 11.1.2 Simulation analysis of large amplitude wave front distortion -- 11.1.3 Experimental Study -- 11.2 Adaptive Optical Wave Front Distortion Correction Using Wave Front Tilt Correction -- 11.2.1 Theoretical wave Front Distortion in Atmospheric Turbulence -- 11.2.2 Wave Front Distortion Experiment in Atmospheric Turbulence -- References.