Image display device, semiconductor device and optical element

摘要

An optical apparatus includes at least an image display device, a light source for illuminating the image display device, a light-receiving device for receiving the light reflected from the eye of an observer, and a calculation device for calculating the line of sight of the observer based on the output of the light-receiving means. At least part of the illuminating light from the light source is utilized as the illuminating light for illuminating the eye of the observer.