| CPC G02B 27/0172 (2013.01) [G02B 27/0179 (2013.01); G02B 27/44 (2013.01); G02B 26/0858 (2013.01); G02B 2027/0178 (2013.01); G02B 2027/0187 (2013.01)] | 16 Claims |

|
1. A display apparatus comprising:
an image providing device configured to provide a plurality of light beams containing an image;
a combiner configured to combine light containing the image, which is emitted from the image providing device, and light containing an external landscape; and
an eye tracker configured to track a location of a pupil of an observer and measure a size of the pupil of the observer,
wherein the combiner comprises a volume grating configured to diffract the light containing the image emitted from the image providing device,
wherein the volume grating has a first surface and a second surface facing each other,
wherein the volume grating is configured to diffract light incident on the first surface and transmit therethrough light incident on the second surface without diffraction, and
wherein the image providing device is further configured to adjust a beam diameter of each light beam of the plurality of light beams incident on the first surface of the volume grating, based on information with respect to the location of the pupil of the observer or information with respect to the size of the pupil of the observer.
|