An investigation was made of the causes of the low precision of phase
locking of two orthogonally polarised low-energy beams. Configurations
capable of at least 95% phase locking of collimated beams with an ove
rall stimulated Brillouin scattering increment of 2-3 and of focused b
eams with a total energy equal to 3-4 thresholds of stimulated Brillou
in scattering were proposed and implemented experimentally.