In fluid mechanics, non-intrusive measurements are fundamental in order to improve knowledge of the behavior and main physical phenomena of flows in order to further validate codes.The principles and characteristics of the different techniques available in laser metrology are described in detail in this book.Velocity, temperature and concentration measurements by spectroscopic techniques based on light scattered by molecules are achieved by different techniques: laser-induced fluorescence, coherent anti-Stokes Raman scattering using lasers and parametric sources, and absorption spectroscopy by tunable laser diodes, which are generally better suited for high velocity flows. The size determination of particles by optical means, a technique mainly applied in two-phase flows, is the subject of another chapter, along with a description of the principles of light scattering.For each technique the basic principles are given, as well as optical devices and data processing. A final chapter reminds the reader of the main safety precautions to be taken when using powerful lasers.

Preface xiIntroduction xiiiAlain BOUTIERChapter 1. Basics on Light Scattering by Particles 1Fabrice ONOFRI and Séverine BARBOSA1.1. Introduction 11.2. A brief synopsis of electromagnetic theory 21.2.1. Maxwell's equations 21.2.2. Harmonic electromagnetic plane waves 41.2.3. Optical constants 91.2.4. Light scattering by a single particle 111.3. Methods using separation of variables 161.3.1. Lorenz-Mie (or Mie) theory 161.3.2. Debye and complex angular momentum theories 261.4. Rayleigh theory and the discrete dipole approximation 291.4.1. Rayleigh theory 291.4.2. Discrete dipole approximation 311.5. The T-matrix method 321.6. Physical (or wave) optics models 341.6.1. Huygens-Fresnel integral 351.6.2. Fraunhofer diffraction theory for a particle with a circular cross section 371.6.3. Airy theory of the rainbow 401.6.4. Marston's physical-optics approximation 441.7. Geometrical optics 471.7.1. Calculation of the scattering angle 481.7.2. Calculation of the intensity of rays 481.7.3. Calculation of the phase and amplitude of rays 491.8. Multiple scattering and Monte Carlo models 501.8.1. Scattering by an optically diluted particle system 501.8.2. Multiple scattering 511.8.3. Monte Carlo method 521.9. Conclusion 571.10. Bibliography 57Chapter 2. Optical Particle Characterization 67Fabrice ONOFRI and Séverine BARBOSA2.1. Introduction 672.2. Particles in flows 692.2.1. Diameter, shape and concentration 692.2.2. Statistical representation of particle size data 702.2.3. Concentrations and fluxes 742.3. An attempt to classify OPC techniques 752.3.1. Physical principles and measured quantities 752.3.2. Nature and procedure to achieve statistics 762.4. Phase Doppler interferometry (or anemometry) 772.4.1. Principle 772.4.2. Modeling the phase-diameter relationship 812.4.3. Experimental setup and typical results 872.4.4. Conclusion 902.5. Ellipsometry 912.6. Forward (or "laser") diffraction 932.6.1. Principle 932.6.2. Modeling and inversion of diffraction patterns 952.6.3. Typical experimental setup and results 982.6.4. Conclusion 1002.7. Rainbow and near-critical-angle diffractometry techniques 1012.7.1. Similarities to forward diffraction 1012.7.2. Rainbow diffractometry 1022.7.3. Near-critical-angle diffractometry 1072.8. Classical shadowgraph imaging 1122.8.1. Principle and classical setup 1122.8.2. One-dimensional shadow Doppler technique 1142.8.3. Calculation of particle images using the point spread function 1152.8.4. Conclusion 1182.9. Out-of-focus interferometric imaging 1192.9.1. Principle 1192.9.2. Modeling the diameter-angular frequency relationship 1202.9.3. Conclusion 1262.10. Holography of particles 1282.10.1. Gabor holography for holographic films 1282.10.2. Inline digital holography 1292.10.3. Conclusion 1312.11. Light extinction spectrometry 1322.11.1. Principle 1322.11.2. Algebraic inverse method 1342.11.3. Experimental setup and conclusion 1362.12. Photon correlation spectroscopy 1392.13. Laser-induced fluorescence and elastic-scattering imaging ratio 1412.13.1. Principle 1422.13.2. Experimental setup and results 1432.13.3. Conclusion 1442.14. Laser-induced incandescence 1442.15. General conclusions 1452.16. Bibliography 146Chapter 3. Laser-Induced Fluorescence 159Fabrice LEMOINE and Frédéric GRISCH3.1. Recall on energy quantification of molecules 1593.1.1. Radiative transitions 1623.1.2. Energy level thermo-statistics 1643.1.3. Franck-Condon principle 1643.1.4. Non-radiative transitions 1643.1.5. Line width 1653.2. Laser-induced fluorescence principles 1683.2.1. Absorption kinetics 1693.2.2. Fluorescence signal 1703.2.3. Fluorescence detection 1733.2.4. Absorption along optical path 1743.2.5. Fluorescence measurement device 1753.3. Applications of laser-induced fluorescence in gases 1773.3.1. Generalities 1773.3.2. Diatomic molecules 1783.3.3. Poly-Atomic molecular tracers 1863.4. Laser-induced fluorescence in liquids 2023.4.1. Principles and modeling 2023.4.2. Fluorescence reabsorption 2053.4.3. Applications to concentration measurement 2053.4.4. Application to temperature measurement 2103.5. Bibliography 218Chapter 4. Diode Laser Absorption Spectroscopy Techniques 223Ajmal MOHAMED4.1. High spectral resolution absorption spectroscopy in fluid mechanics 2234.2. Recap on molecular absorption 2264.2.1. Line profile 2264.2.2. Line strength 2284.3. Absorption spectroscopy bench 2294.3.1. Emitting optics 2304.3.2. Optical detection 2344.3.3. Spectra processing 2374.4. Applications in hypersonic 2454.4.1. F4 characteristics 2464.4.2. Setup installed at F4 2484.4.3. Results obtained at F4 and HEG 2494.5. Other applications of diode laser absorption spectroscopy 2504.5.1. Combustion applications 2504.5.2. Applications to atmospheric probing 2534.6. Other devices for diode laser absorption spectroscopy 2544.6.1. Multipass spectrometry 2544.6.2. Spectrometry in a resonant cavity 2574.7. Perspectives and conclusion on diode laser absorption spectroscopy 2614.7.1. Laser source: use of non-cryogenic diodes 2624.7.2. Spatial resolution: use of probe in flow 2624.7.3. Use of frequency combs 2644.8. Bibliography 264Chapter 5. Nonlinear Optical Sources and Techniques for Optical Diagnostic 271Michel LEFEBVRE5.1. Introduction to nonlinear optics 2715.2. Main processes in nonlinear optics 2725.2.1. Propagation effects 2735.2.2. Second- and third-order nonlinearities 2765.2.3. Phase matching notion 2805.3. Nonlinear sources for optical metrology 2825.3.1. Sum frequency generation and frequency doubling 2835.3.2. Raman converters 2855.3.3. Optical parametric generators and oscillators 2895.4. Nonlinear techniques for optical diagnostic 2965.4.1. Introduction to four-wave mixing techniques 2965.4.2. Temperature and concentration measurements in four-wave mixing 2995.4.3. Velocity measurements in four-wave mixing 3015.5. Bibliography 305Chapter 6. Laser Safety 307Jean-Michel MOST6.1. Generalities on laser safety 3076.2. Laser type and classification 3086.3. Laser risks: nature and effects 3106.3.1. Biological risks 3106.3.2. Risks to the eye 3126.3.3. Risks to the skin 3146.3.4. Risk to hearing 3156.3.5. Other biological risks 3156.4. Protections 3166.4.1. Accident prevention 3166.4.2. Collective protection 3166.4.3. Individual protection 3186.5. Safety advice 3196.6. Human behavior 320Conclusion 321Alain BOUTIERNomenclature 323List of Authors 329Index 331