Planar laser Rayleigh

Espey, C., Dec, J. E., Litzinger, T. A., and Santavicca, D. A., Planar Laser Rayleigh Scattering for Quantitative Vapor-Puel Imaging in a Diesel Jet, Combustion and Flame, 109 65-86, 1997. 

The laser-based techniques currently being used and developed include vibrational Raman scattering, coherent anti-Stokes Raman scattering (CARS), Rayleigh scattering, laser-induced fluorescence, and planar laser-induced fluorescence (PLIF). This is an active research field at various research establishments. Laser-induced fluorescence spectroscopy has been used to measure several combustion intermediates, for example, CH, C2, HCH, OH, NO, NO2, HNO, CO, halogenated hydrocarbons, and polycyclic aromatic hydrocarbons. 

Laser ultrasonic transducers are truly non-contact devices which effectively avoid acoustic coupling problems (e.g. damping in the transducer and couplant reflection and transmission losses at the interface). Most laser ultrasonic devices have been used for excitation and detection of bulk elastic waves in point source or planar geometry, but also surface acoustic (Rayleigh or Brillouin) waves. Unlike the bulk wave regime, only one sample side is needed for excitation and detection when surface waves are used. This not only renders the measurements easier, but also avoids the need for an accurate knowledge and uniformity of the sample thickness. In addition, the excitation laser can be focused using cylindrical lenses in order to obtain an excitation line. 

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