We use stimulated Brillouin scattering to investigate phase conjugation of a laser beam aberrated by one or more phase screens when the aberrated beam is incompletely sampled by the phase-conjugate mirror. Good agreement is found between our experimental results and previous theoretical work. We find that the fraction of the reflected beam that is phase conjugate after the double pass is proportional to the fraction of the original beam sampled by the phase-conjugate mirror. We also show that it is possible to increase the resolution of a phase-conjugate mirror by inserting an aberrator.
D. C. Jones and K. D. Ridley, "Experimental investigation by stimulated Brillouin scattering of incomplete phase conjugation," J. Opt. Soc. Am. B 14, 2657-2663 (1997)