Patent US 5,225,862

An optical apparatus which detects a visual axis using plural reflected images of a light source includes an observation device with which an observer observes an object. An image sensor is provided for generating a signal and response to an image. Optical structure is provided for forming a plurality of reflected light source images on the image sensor by reflection of light from the eye of the observer. The optical structure includes (1) an illumination assembly for projecting a light beam from at least one light source to the eye of the observer, and (2) a convergence component having at least one convergent lens for converging the light beam reflected from the eye of the observer, to produce the plurality of reflected light source images. The optical structure includes at least two light sources and/or two convergent lenses. An electrical circuit is coupled to the image sensor for generating (1) information relating to a working distance between the plurality of reflected light source images reflected from the eye, and (2) information relating to the reflected image of a front eye part, to generate information relating to a direction of the visual axis of the eye.