  We study the scintillation index of N partially overlapping collimated lowest
order Gaussian laser beams with different wavelengths in weak atmospheric
turbulence. Using the Rytov approximation we calculate the initial beam
separation that minimizes the longitudinal scintillation. Further reduction of
the longitudinal scintillation is obtained by optimizing with respect to both
beam separation and spot size. The longitudinal scintillation of the optimal
N-beam configurations is inversely proportional to N, resulting in a 92%
reduction for a 9-beam system compared with the single beam value. The radial
scintillation values for the optimal N-beam configurations are significantly
smaller than the corresponding single beam values.
