We present the design and characterization of a quasi-homogeneous, planar electromagnetic source to produce beam-like optical fields with controllable spatial coherence and polarization properties. Dynamic control of the second-order correlation properties of an optical beam is achieved by controlling the spectral density and polarization state distributions at the source plane, as described by the generalized van Cittert-Zernike theorem for the cross-spectral density matrix of a quasi-homogeneous, planar electromagnetic source. In the proposed design, the spectral density distributions of orthogonal linear polarization components at the quasi-homogeneous source are controlled using a spatial light modulator. The beam generated in this way propagates to the far-field region yielding the desired spatial coherence and polarization state distributions. With this source we can generate an optical beam that is unpolarized in the usual one-point polarization sense, but polarized in the two-point mutual polarization sense. That is, the beam has a polarization distribution where two orthogonal linear polarization components at two points, within the aperture of the beam, separated by a set vector, given by the spectral density distribution at the source, are fully correlated. A beam with that polarization distribution may be used to perform the measurements required by variable coherence polarimetry, which can be applied to estimate the polarimetric bidirectional reflectance distribution function from monostatic measurements, with promising applications in remote sensing.
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