Characteristic features of images of an object eye are extracted to enable non-contact detection of eye movement. Two images of the eye are focused, and a differential image is generated to eliminate background noise and to permit feature extraction to be performed. In one feature of the invention, the illuminating light is polarized for use as a reference and the reflected light is separated to two light paths, each of which is focused to form an image of the object. In one path a polarizing plate blocks the regularly reflected light from the cornea so that only a diffused reflection component of the illuminating light from the other parts of the eye is passed, while in the other path both the regularly and diffusedly reflected light components are passed. A resulting differential image emphasizes the regular reflection component from the cornea relative to the background. In another aspect of the invention, two light sources are placed at different positions relative to the optical axis, to provide bright and dark images of the pupil without otherwise affecting the reflected image. A resulting differential image emphasizes the pupil relative to background noise.