A head up display includes a light pipe and a waveguide combiner. The light pipe is configured to expand a pupil in a first direction and includes an input grating and an output put grating. The light pipe also includes four elongated surfaces, and the input grating and the output grating are provided in one or more planes parallel to two of the elongated surfaces. The waveguide combiner is configured to expand the pupil in a second direction perpendicular to the first direction. The first light pipe is disposed at an angle with respect to a waveguide combiner.