ABSTRACT
It is undeniable that one of the scientic disciplines undergoing an unprecedented level of development is laser spectroscopy, which could be dened as the countless collection of techniques aiming at the extraction of
physical and chemical information from the interaction between the matter in any phase (solid, liquid, or gas) and the electromagnetic elds created by one or more laser beams [1-5]. Certainly, the advent of efcient, powerful, reliable, and commercially available laser systems has boosted many scientic and technological achievements encompassing basic and industrial applications
Michele Marrocco and Guido Troiani
CONTENTS
12.1 Purpose of Laser Measurements .............................................................................................................................. 269 12.2 Materials for Laser Measurements ........................................................................................................................... 270
12.2.1 Lasers ............................................................................................................................................................. 270 12.2.2 Optical Elements ........................................................................................................................................... 271 12.2.3 Spectral Dispersion and Detection ............................................................................................................ 272
12.3 Laser Measurements for Chemical Species............................................................................................................. 272 12.3.1 Incoherent Techniques ................................................................................................................................. 273
12.3.1.1 Laser Induced Fluorescence (LIF) ..............................................................................................274 12.3.1.2 Spontaneous Raman Scattering (SpRS) .....................................................................................274 12.3.1.3 Other Incoherent Techniques for Detection of Chemical Species ........................................ 275
12.3.2 Coherent Techniques.................................................................................................................................... 276 12.3.2.1 Coherent Anti-Stokes Raman Scattering (CARS) ................................................................... 276 12.3.2.2 Degenerate Four Wave Mixing (DFWM) ................................................................................. 277 12.3.2.3 Other Coherent Techniques for the Detection of Chemical Species .................................... 278
12.4 Laser Measurements for Velocimetry ...................................................................................................................... 278 12.4.1 Laser Doppler Velocimetry (LDV) ............................................................................................................. 279 12.4.2 Particle Image Velocimetry (PIV) ............................................................................................................... 279
12.5 Laser Measurements for Particle Sizing .................................................................................................................. 280 12.5.1 Laser Doppler Velocimetry (LDV) ............................................................................................................. 280 12.5.2 Phase Doppler Anemometry (PDA) or Velocimetry (PDV) ................................................................... 281 12.5.3 Other Laser Techniques for Particle Sizing .............................................................................................. 281
12.6 Laser Measurements for Thermometry ................................................................................................................... 281 12.6.1 Rayleigh Thermometry ................................................................................................................................ 282 12.6.2 LIF Thermometry ......................................................................................................................................... 283
12.6.2.1 LIF Thermometry with Excitation Scans ................................................................................. 283 12.6.2.2 LIF Thermometry with Two-Color Approach ......................................................................... 283 12.6.2.3 LIF Thermometry with Thermal Assistance ........................................................................... 283
12.6.3 Raman-Based Techniques for Thermometry ........................................................................................... 284 12.6.3.1 Thermometry with SpRS ............................................................................................................ 284 12.6.3.2 Thermometry with CARS .......................................................................................................... 284
12.6.4 Other Thermometric Laser Techniques .................................................................................................... 285 12.7 Combined Laser Measurements ............................................................................................................................... 285
12.7.1 Examples of Combined Measurements ..................................................................................................... 286 References ................................................................................................................................................................................ 286
as well as research at the cutting edge of science. It is then not surprising that the understanding of atomic and molecular physics is going through a ourishing time thanks to the vital role of laser measurements [1-5]. Needless to say, the same applies to combustion science [6-9]. In this context, the introduction of lasers has powered the understanding of the multifaceted processes happening in various combustion environments and often involving the ability to deal with the interdisciplinary subtleties of chemistry, molecular physics, and uid-dynamics that challenge the scientist as well as the practitioner. Not only are such accomplishments distinctive of fundamental combustion research, but also industrial combustion benets from them [10-22]. In retrospect, we can say that combustion science would have failed many advances without the assistance of laser spectroscopy necessary to remotely generate and interpret data about chemical compositions, temperatures, velocities, and so on. It is then obvious to reach the conclusion that laser measurements in combustion science are planned according to important diagnostic criteria that will be reviewed here.
