A display can be utilized with an image source. The display includes a collimator and a substrate waveguide. The substrate waveguide sees collimated light from the collimator at an input and provides the collimated light to an output. The collimated light travels from the input to the output within the substrate by total internal reflection. An input diffraction grating is disposed in a first area at the input and an output diffraction grating is disposed in a second area at the output. The second diffraction grating is matched to the first diffraction grating. A combiner alignment detector is not required due to the periscopic effect according to one embodiment.