  We presented a new method for measuring the squares of the amplitudes and
phases of partial vortex-beams in a complex beam array in real time. The method
is based on measuring the high-order intensity moments and analyzing the
solutions of a system of linear equations. Calibration measurements have shown
that the measurement error at least for an array of 10-15 beams does not exceed
4%. It has theoretically and experimentally been shown that the orbital angular
momentum (OAM) of combined singular beams depends essentially on the fractional
topological charge p. For integer values of the topological charge, the OAM
obtains the maximum value numerically equal to the topological charge of the
singular beam. With weak deviations of the topological charge in the direction
of fractional values, dips in the orbital moment appear. . It was
experimentally shown that even a weak perturbation of the holographic grating
leads to a sharp increase in the contribution of partial beams with other
integer-order topological charges.
