| abstract |
An optical apparatus comprises at least image display device (102), a light source (101) for illuminating the image display device (102), light-receiving device (110) for receiving the light reflected from the eye (105) of an observer, and calculation device (112) for calculating the line of sight of the observer based on the output of the light-receiving means (110). At least, a part of the illuminating light from the light source (101) is utilized as the illuminating light for illuminating the eye of the observer. |