1. A system for capturing an image of a retina of an eye for identification comprising: a source of illumination light; a lens through which the illumination light passes to illuminate the retina, the lens receiving light reflected from the retina; an image signal generator responsive to light reflected from the retina to generate a signal representing an image of an illuminated area of the retina; and an alignment system including an ultrasound transducer, the system being responsive to the transducer to determine when the eye is a predetermined distance from the image capturing system and providing an indication to the user when the eye is at the predetermined distance.