  We study the interference between two parallel-propagating Gaussian beams,
originated from the same source, as their transverse separation is tuned. The
interference pattern as a function of such separation lead us to determine the
spatial coherence length of the original beam, in a similar way that a
Michelson-Morley interferometer can be employed to measure the temporal
coherence of a transform limited pulse. Moreover, performing a Fourier
transform of the two-beam transverse plane, we observe an intensity modulation
in the transverse momentum variable. This observation resembles the Alford and
Gold Effect reported in time and frequency variables so far.
