Abstract: An interferometric testing system and method employing a multiple-aperture hologram. In an illustrative embodiment, the inventive optical testing system includes an interferometer which outputs a planar light beam and analyzes a reflected selected light beam. A multiple-aperture hologram generates N image points in an image plane of the optical system responsive to the planar light beam. A retro-reflector reflects a selected one of N light beams corresponding to the N image points transmitted by the optical system back through the optical system to generate the selected light beam. According to one aspect of the present invention, the multiple-aperture hologram includes N apertures generating the N image points and one of the N apertures overlaps at least one other of the N apertures. According to another aspect of the invention, the multiple-aperture hologram intersects a plane perpendicular to an axis defined by the centers of the interferometer and the retro-reflector.