1. A virtual image display system comprising: a source of photons modulated with video information, said photons being scanned directly onto the retina of the user's eye to produce a virtual image perceived by the user without an aerial image outside of the user's eye perceivable by the user wherein said video information represents a plurality of picture elements of a video image and means for varying the focus of said scanned photons to control the depth perceived for each picture element of said video image.