The main topic of this group is the Optical metrology of particles in flows. A special attention is devoted to simultaneous measurements of different parameters as velocity, dimension, form, concentration 3D location, temperature, chemical composition. Different models are developed to describe, predict and understand precisely the experimental results.
The development of new metrologies requires the control of the whole experimental set-up:
- The spatial and temporal optimization of the laser beam characteristics (in Continuous Wave or Pulsed regimes),
- The description of the linear and nonlinear interactions between any incident laser beam and scattering particle(s) (theoretical and numerical research activity),
- The data acquisition and analysis. An important topic concerns image processing.
This approach requires to establish regular links between different domains of investigation:
- The development of rigorous models (analytical resolution of Maxwell equations ( Generalized Lorenz-Mie theory, Quantum Mechanics…) or approached scalar models (diffraction, ABCD transfer matrix),
- The development of the corresponding numerical codes,
- The realization of experiences and the comparison with models.
The main techniques that are under development in the group are digital holography, Rainbow technique, LII, Interferometric Laser Imaging Droplet Sizing, phase contrast metrology.
Some examples of recent activities:
- Interaction between a laser beam and inhomogeneous particles, Optical chaos.
- Optical characterization of particles in flows (velocity, position, diameter, temperature,...)
- Développement of new techniques (Digital holography, Rainbow technique…).
- In situ flow measurements in pipes or micropipes. Microfluidics.
- Characterization of low density particle clouds using femtosecond techniques.