Experimental investigation of transitional free shear layer optics
Measurements of Strehl ratio vs downstream distance, when a beam propagates through a shear layer (Reynolds number=810/length), reveal minimal phase distortion in the pretransition region and a sudden decrease in the Strehl ratio when transition occurs. The Strehl ratio levels off to a constant asymptotic value (which is a function of the velocity ratio) in the post-transtion region. The constant Strehl ratio (in the fully developed region) is attributed to fast mixing that occurs within the core of the vortices