Spatial resolution-preserving retroreflection for gas-phase laser scattering measurements in turbulent flames using a phase-conjugate mirror.

This Letter reports on the demonstration of a stimulated Brillouin-scattering phase conjugate mirror (SBS-PCM) for multipass laser-based scattering measurements in turbulent flames. Retroreflective measurements using the SBS-PCM show substantial improvements in spatial-resolution preservation as compared to measurements using a conventional mirror as a multipass reflector. The results using the SBS-PCM indicate an insensitivity to large index-of-refraction gradients and preservation of the original spatial resolution as defined by the laser beam under reacting flow conditions. This approach offers the possibility of increasing signal-to-noise ratios within low-signal gas-phase measurements such as Rayleigh and Raman scattering.