Beam shaping for CARS measurements in turbulent environments.

ABSTRACT

This paper describes a new technique to mitigate the effect of beam steering on CARS measurements in turbulent, variable density environments. The new approach combines planar BOXCARS phase-matching with elliptical shaping of one of the beams to generate a signal robust to beam steering, while keeping the same spatial resolution. Numerical and experimental results are provided to demonstrate the effectiveness of this approach. One experiment investigates the effect of beam shaping in the presence of a controlled and well quantified displacement of the beams at the focal plane. Another experiment, more qualitative, proves the effectiveness of the technique in the presence of severe beam steering due to turbulence.