The present disclosure generally relates to frustrated cube assemblies having a first prism having a first surface, a second surface, and a first hypotenuse, and a second prism having a third surface, a fourth surface, and a second hypotenuse. The first and second hypotenuses face one another and are separated by an air gap. The frustrated cube assembly may include a tilted mirror adjacent the second surface. The second surface may be a reflective diffraction grating. Light is reflected to a digital micromirror device (DMD) adjacent to the frustrated cube assembly at a normal incidence angle and through an image projection system along a single optical axis. The direction of light incident on the DMD is such that light reflected from an “on” mirror is directed along the normal to the DMD surface and at 45 degrees to the hypotenuses. The input and output light beams are parallel.