An optical system is provided for use with a display device to convert a flat image from the display device to a non-flat image. The optical system comprises first and second spaced-apart partial reflectors, at least one of which is non-flat. The reflectors, together with polarization optics, provide a light path such that light from the display is at least partially transmitted by the first reflector, partially reflected by the second reflector, partially reflected by the first reflector and partially transmitted by the second reflector so that a viewer perceives a non-flat, for example curved, image. Light which does not follow the light path is prevented from leaving the optical system.