Provided is a display device including a light guide plate; a reflective prism configured to reflect an imaging beam toward the light guide plate, wherein the imaging beam reflected by the reflective prism travels within the light guide plate at an angle greater than a critical angle of the light guide plate; and a diffraction grating configured to diffract the imaging beam traveling within the light guide plate to an angle less than or equal to the critical angle of the light guide plate, wherein the reflective prism includes a first surface in contact with the light guide plate, and a second surface configured to reflect the imaging beam.