Gravitational lensing of a binary system with complex light beams

We investigate the diffraction patterns of light deflected by the curvature of space-time produced by a binary system. We do this in the laboratory by imparting the deflections produced by a gravitational binary lens via a spatial light modulator. The diffraction patterns illustrate the coexistence of geometric and wave optics. They consist of diffraction interference patterns bound by caustic figures. These figures change as a function of the mass of the objects, their separation, and propagation distance. We study their invariance via a scaling parameter that combines the three variables. The size and shape of the patterns are invariant to the wavelength of the light but not the density of interference maxima and minima contained within. Comparisons with theoretical calculations are excellent.