  We describe an experimental technique to generate a quasi-monochromatic field
with any arbitrary spatial coherence properties that can be described by the
cross-spectral density function, $W(\mathbf{r_1,r_2})$. This is done by using a
dynamic binary amplitude grating generated by a digital micromirror device
(DMD) to rapidly alternate between a set of coherent fields, creating an
incoherent mix of modes that represent the coherent mode decomposition of the
desired $W(\mathbf{r_1,r_2})$. This method was then demonstrated experimentally
by interfering two plane waves and then spatially varying the coherent between
these two modes such that the interference fringe visibility was shown to vary
spatially between the two beams in an arbitrary and prescribed way.
