The present invention relates to a projection display (10) for displaying an image to a viewer, comprising a curved waveguide (14) made of light transmissive material and having first and second opposed curvilinear surfaces (26, 28), an image-providing light source device arranged to inject collimated image bearing light into the waveguide, an input grating (20) coupled to or within the waveguide to diffract said image bearing light to propagate internally along the curved waveguide by total internal reflection, an output grating (22) provided along a side of the waveguide by which the image bearing light is diffracted out of the waveguide for viewing by the viewer, wherein the input grating and output grating have variable pitch gratings so that a collimated image injected into the waveguide can be output from the waveguide as a collimated image having an increased exit pupil.